My Truck is DEAD! Please Help

Hi All,

I have a 2003 Avalanche that is the ground FX edition.  It recently has been giving me alot of grief and I was hoping you folks could point me in the right direction. 

The other day while driving down the highway the engine light came on and the dash gave me a warning "Reduced Engine Power".  This knocked me down to a max speed of about 20mph  and the RPM would not climb above 1000.  I took it in right away to get the Code read and they said the throttle was sticking.  They though the butterfly in the throttle body was possibly sticking.  The fix for this was to loosen the throttle body and re-torque it.  After this was done the problem appeared to be fixed for a few mins.  Again the same warning came up along with a ABS warning/Service light.  Shortly after this the truck died and would not start.  A security light was on in the dash along with the seatbelt light.  The truck would not even attempt to start until the seatbelt light went off.  It would start up again but only for about 40 secs and then would die and the process would start over. 

    I was hoping maybe some of you could help me out.  I'm thinking it has to be computer related since som many things are messing up.  Also when you do get it started and attempt to drive the power locks constantly flick from locked to unlocked.  If any of you have any ideas please let me know where I can get started. 

Thanks,

Been wantin' an '05 anyway, right

I'm reserving comment till more information is provided but here are my first two guesses...they don't really count since we don't have near enough information to start being helpful...













igniton switch or battery

Whats a ground FX edition 

The first problem you describe I had. It had nothing to do with the throttle body being loose. It was a poor connection to the electronic throttle motor. Remove plug, spray electronic cleaner, dry and apply some dielectric grease to terminals and reconnet. That solved my problem

More info on truck.

5.3L
70,000 km
all options except On Star.
4x4
any other needed info.

Thanks Again

CKP Sensor?....
Checking..

Here's one, I see three..

Reduced Engine Power - DTCs P0120 , P0220 , P1516 and/or P1518 - 03 Model Year Full Size Trucks and Utilities with 4.8 , 5.3 or 6.0 Engines - kw CEL light low LQ4 LQ9 LR4 MIL reducedpwrmde #PIP3042A - (Aug 30, 2004)

The following diagnosis might be helpful if the vehicle exhibits the symptom described in the PI.

Condition/Concern:

Service Engine Soon Light and / or Reduced Engine Power Mode due to any of the following DTCs: P0120, P0220, P1516 and/or P1518.

Recommendation/Instructions:

If the SI diagnosis and bulletin 03-06-04-032 did not isolate a concern, the following information may help:.

  1. Inspect the Yellow TAC Motor Control Circuit (581) about 1 inch to 4 inches from the throttle body connector to see if it is broken inside of the insulation.
  2. Inspect S102 if there is a P1518 stored. S102 is in the engine harness and is 5.5 inches from the MAP Sensor.
  3. Install that latest engine diagnostic calibrations in the PCM. Some 2003 model year vehicles have updated engine diagnostic calibrations available to address DTCs P0120, P0220, P1516 and or P1518. The title of the updated engine diagnostic calibration in TIS2000 is "New calibration to eliminate setting of P0120, P0220, or P1516 with the engine not running. Includes diagnostic enhancements for P1518."

If the above did not help, replace the throttle body and retorque it to 45 lb/in on the 1st pass and 89 lb/in on the second and final pass.

Please follow this diagnosis process thoroughly and complete each step. If the condition exhibited is resolved without completing every step, the remaining steps do not need to be performed. If these steps do not resolve the condition, please contact GM TAC for further diagnostic assistance.

Models:

(03 Cadillac Escalade) and (03 Chevrolet Avalanche) and (03 Chevrolet Silverado)and (03 Chevrolet Suburban) and (03 Chevrolet Tahoe) and (03 GMC Sierra) and (03 GMC Yukon) and (03 Hummer H2)

The second one:

SES Light and Reduced Engine Power with a DTC P1516: DTCs P0120 , P0220 , P1514 , P1515 , P1518 and P2135 May Be Present; 04 Trucks and Utilities with GENIII V-8 Engines - kw 4.8 5.3 6.0 #PIP3089 - (Jul 30, 2004)

The following diagnosis might be helpful if the vehicle exhibits the symptom described in the PI.

Condition/Concern:

SES light and reduced engine power with a DTC P1516. DTCS P0120, P0220, P1514, P1515, P1518 and P2135 may also be present.

Recommendation/Instructions:

If the SI diagnostics do not isolate the cause, inspect the Yellow TAC Motor Control Circuit (581) about 1 inch to 4 inches from the throttle body connector to see if it is broken inside of the insulation. Repair as necessary.

Please follow this diagnosis process thoroughly and complete each step. If the condition exhibited is resolved without completing every step, the remaining steps do not need to be performed. If these steps do not resolve the condition, please contact GM TAC for further diagnostic assistance.

Models:

(03 - 04 Cadillac Escalade C1, C6, K1, K6) and (03 - 04 Chevrolet Avalanche C1, K1, C2, K2) and (03 - 04 Chevrolet Silverado Truck C1, K1, C2, K2, C3, K3 ) and (03 - 04 Chevrolet Tahoe C1, K1 ) and (03 - 04 Chevrolet Suburban C1, K1, C2, K2, C3, K3 ) and (03 - 04 GMC Sierra Truck C1, K1, C2, K2, C3, K3 ) and (03 - 04 GMC Yukon C1, K1 ) and (03 - 04 GMC Yukon XL C1, K1, C2, K2, C3, K3) and (03 - 04 Hummer H2 N2 ) and (03 - 04 Buick Rainier S1, T1 ) and (03 - 04 Chevrolet Trail Blazer EXT S1, T1 ) and (03 - 04 GMC Envoy XL XUV S1, T1)

And the 3rd one.. (8.1L)

03 8.1 L18 Reduced Engine Power Due to DTCs P0120 , P0220 , P1516 and / or P1518 - kw CEL GMT800 GMT805 GMT830 light low MIL reduced reducedpwrmde #PIP3040 - (Jun 30, 2004)
03 8.1 L18 Reduced Engine Power Due to DTCs P0120 P0220 P1516 and / or P1518

The following diagnosis might be helpful if the vehicle exhibits the described symptoms in the PI.

Condition/Concern:

Service Engine Soon Light and / or Reduced Engine Power Mode due to any of the following DTCs: P0120, P0220, P1516 and/or P1518. This condition is normally very intermittent.

Recommendation/Instructions:

If the published diagnostics did not isolate a concern, the following information may help:

  1. Inspect G104 on the rear of the left cylinder head. See SI document 818627, if necessary.
  2. Install that latest engine diagnostic calibrations in the PCM. Some 2003 model year vehicles have updated engine diagnostic calibrations available to address DTCs P0120, P0220, P1516 and or P1518. The title of the updated engine diagnostic calibration in TIS2000 is "New calibration to eliminate setting of P0120, P0220, or P1516 with the engine not running. Includes diagnostic enhancements for P1518."

Please follow this diagnosis process thoroughly and complete each step. If the condition exhibited is resolved without completing every step, the remaining steps do not need to be performed. If these steps do not resolve the condition, please contact GM TAC for further diagnostic assistance.

Models:

(03 Chevrolet Avalanche C2, K2) and (03 Chevrolet Silverado C2, C3, K2, K3) and (03 Chevrolet Suburban C2, C3, K2, K3) and (03 GMC Sierra C2, C3, K2, K3) and (03 GMC Yukon XL C2, C3, K2, K3)

DTC P0120  (Brief)

Circuit Description

The throttle position (TP) sensor 1 is a potentiometer type sensor with three circuits:

    * A 5-volt reference circuit
    * A low reference circuit
    * A signal circuit

The TP sensor is used to determine the throttle plate angle for various engine management systems. The control module provides the TP sensor a 5-volt reference circuit and a low reference circuit. The TP sensor then provides the control module a signal voltage proportional to throttle plate movement. TP sensor 1 signal voltage is low at closed throttle and increases as the throttle opens. When the control module detects that the TP sensor 1 signal or TP sensor 5-volt reference voltage is outside the predetermined range, this DTC sets.

Conditions for Running the DTC

    * DTCs P1518 or P2108 are not set.
    * The ignition switch is in the crank or run position.
    * The ignition voltage more than 5.23 volts.

Conditions for Setting the DTC

    * The TP sensor 1 signal voltage is less than 0.37 volt or more than 4.51 volts.
    * The above condition is present for more than 1 second.

Action Taken When the DTC Sets

    * The control module illuminates the malfunction indicator lamp (MIL) when the diagnostic runs and fails.
    * The control module records the operating conditions at the time the diagnostic fails. The control module stores this information in the Freeze Frame and/or the Failure Records.
    * The control module commands the TAC system to operate in the Reduced Engine Power mode.
    * A message center or an indicator displays Reduced Engine Power.
    * Under certain conditions the control module commands the engine OFF.

Conditions for Clearing the MIL/DTC

  ? The control module turns OFF the malfunction indicator lamp (MIL) after 3 consecutive ignition cycles that the diagnostic runs and does not fail.
  ? A current DTC, Last Test Failed, clears when the diagnostic runs and passes.
  ? A history DTC clears after 40 consecutive warm-up cycles, if no failures are reported by this or any other emission related diagnostic.
  ? Clear the MIL and the DTC with a scan tool.

DTC P0220

Circuit Description

The throttle position (TP) sensor 2 is a potentiometer type sensor with three circuits:

    * A 5-volt reference circuit
    * A low reference circuit
    * A signal circuit

The TP sensor is used to determine the throttle plate angle for various engine management systems. The control module provides the TP sensor a 5-volt reference circuit and a low reference circuit. The TP sensor then provides the control module a signal voltage proportional to throttle plate movement. TP sensor 1 signal voltage is low at closed throttle and increases as the throttle opens. When the control module detects that the TP sensor 2 signal or TP sensor 5-volt reference voltage is outside the predetermined range, this DTC sets.

Conditions for Running the DTC

    * DTCs  P1518 or P2108 are not set.
    * The ignition switch is in the crank or run position.
    * The ignition voltage is more than 5.23 volts.

Conditions for Setting the DTC

    * The TP sensor 2 voltage is less than 0.28 volt or greater than 4.60 volts.
    * The above condition is present for more than 1 second.

Action Taken When the DTC Sets

    * The control module illuminates the malfunction indicator lamp (MIL) when the diagnostic runs and fails.
    * The control module records the operating conditions at the time the diagnostic fails. The control module stores this information in the Freeze Frame and/or the Failure Records.
    * The control module commands the TAC system to operate in the Reduced Engine Power mode.
    * A message center or an indicator displays Reduced Engine Power.
    * Under certain conditions the control module commands the engine OFF.

Conditions for Clearing the MIL/DTC

  ? The control module turns OFF the malfunction indicator lamp (MIL) after 3 consecutive ignition cycles that the diagnostic runs and does not fail.
  ? A current DTC, Last Test Failed, clears when the diagnostic runs and passes.
  ? A history DTC clears after 40 consecutive warm-up cycles, if no failures are reported by this or any other emission related diagnostic.
  ? Clear the MIL and the DTC with a scan tool.

Diagnostic Aids

  ? Inspect the throttle actuator control (TAC) module connectors for signs of water intrusion. If water intrusion occurs, multiple DTCs may set without any circuit or component conditions found during diagnostic testing.
  ? When the TAC module detects a condition within the TAC system, more than 1 TAC system related DTC may set. This is due to the many redundant tests run continuously on this system. Locating and repairing 1 individual condition may correct more than 1 DTC. Disconnecting components during testing may set additional DTCs. Remember this if you review the stored information in Capture Info.

  ? If this DTC is determined to be intermittent, refer to Intermittent Conditions .

DTC P1515 (Brief, as all above)

Circuit Description

The commanded throttle position (TP), based on accelerator pedal position (APP) and possibly other limiting factors, is compared to the actual TP. The 2 values should be within a calibrated range of each other. Both the powertrain control module (PCM) and the throttle actuator control (TAC) module redundantly monitor the commanded and actual TP. This DTC sets if the PCM detects an out-of-range condition between commanded and actual throttle position.

Conditions for Running the DTC

    * DTCs P0601, P0602, P0604, P0606, P1516, P1518, P2108 are not set.
    * DTCs P0120, P0220, P2135 are not active at the same time.
    * DTCs P0120 and P0220 are not active at the same time.
    * The ignition switch is in the crank or run position.
    * The ignition voltage is more than 8.5 volts.
    * The TAC system is not in the battery saver mode.

Conditions for Setting the DTC

    * The PCM detects that the commanded and actual throttle positions are not within a calibrated range of each other.
    * The above condition is met for less than 1 second.

Action Taken When the DTC Sets

    * The control module illuminates the malfunction indicator lamp (MIL) when the diagnostic runs and fails.
    * The control module records the operating conditions at the time the diagnostic fails. The control module stores this information in the Freeze Frame and/or the Failure Records.
    * The control module commands the TAC system to operate in the Reduced Engine Power mode.
    * A message center or an indicator displays Reduced Engine Power.
    * Under certain conditions the control module commands the engine OFF.

Conditions for Clearing the MIL/DTC

  ? The control module turns OFF the malfunction indicator lamp (MIL) after 3 consecutive ignition cycles that the diagnostic runs and does not fail.
  ? A current DTC, Last Test Failed, clears when the diagnostic runs and passes.
  ? A history DTC clears after 40 consecutive warm-up cycles, if no failures are reported by this or any other emission related diagnostic.
  ? Clear the MIL and the DTC with a scan tool.

Diagnostic Aids

    ? Inspect for mechanical concerns or binding that may be temperature related. Components may not move freely in extreme heat or cold due to the presence of contaminants or ice formation.
    ? Inspect the TAC module connectors for signs of water intrusion. If water intrusion occurs, multiple DTCs may set without any circuit or component conditions found during diagnostic testing.
    ? When the TAC module detects a condition within the TAC system, more than 1 TAC system related DTC may set. This is due to the many redundant tests run continuously on this system. Locating and repairing an individual condition may correct more than 1 DTC. Disconnecting components during testing may set additional DTCs. Remember this if you review the stored information in Capture Info.
    ? For an intermittent, refer to Intermittent Conditions .

DTC P1516

Circuit Description

The predicted throttle position (TP) is compared to the actual throttle position. The two values should be within a calibrated range of each other. Both the powertrain control module (PCM) and the throttle actuator control (TAC) module redundantly monitor the predicted and actual throttle position. This DTC sets if the PCM detects an out of range condition between the predicted and actual throttle position.

Conditions for Running the DTC

  ? DTC P1518 is not set.
  ? The ignition switch is in the crank or run position.
  ? The ignition voltage is more than 5.23 volts.
  ? The TAC system is not in the battery saver mode.

Conditions for Setting the DTC

  ? The TAC module detects that the predicted and the actual throttle positions are not within a calibrated range of each other.
  ? The PCM and the TAC cannot determine the throttle position.
  ? Both of the TP sensors are invalid.
  ? All of the above conditions are met for more than 1 second.

Action Taken When the DTC Sets

    ? The control module illuminates the malfunction indicator lamp (MIL) when the diagnostic runs and fails.
    ? The control module records the operating conditions at the time the diagnostic fails. The control module stores this information in the Freeze Frame and/or the Failure Records.
    ? The control module commands the TAC system to operate in the Reduced Engine Power mode.
    ? A message center or an indicator displays Reduced Engine Power.
    ? Under certain conditions the control module commands the engine OFF.

Conditions for Clearing the MIL/DTC

  ? The control module turns OFF the malfunction indicator lamp (MIL) after 3 consecutive ignition cycles that the diagnostic runs and does not fail.
  ? A current DTC, Last Test Failed, clears when the diagnostic runs and passes.
  ? A history DTC clears after 40 consecutive warm-up cycles, if no failures are reported by this or any other emission related diagnostic.
  ? Clear the MIL and the DTC with a scan tool.

Diagnostic Aids

  ? Inspect the TAC module connectors for signs of water intrusion. If water intrusion occurs, multiple DTCs may set without any circuit or component conditions found during diagnostic testing.
  ? Verify that the starting and charging systems are operating properly. Low system voltage can cause this DTC to set.
  ? When the TAC module detects a condition within the TAC system, more than 1 TAC system related DTC may set. This is due to the many redundant tests run continuously on this system. Locating and repairing an individual condition may correct more than 1 DTC. Disconnecting components during testing may set additional DTCs. Remember this if you review the stored information in Capture Info.
  ? For an intermittent, refer to Intermittent Conditions .

DTC P1518

Circuit Description

The throttle actuator control (TAC) module and the powertrain control module (PCM) communicate via a dedicated serial data circuit. This serial data circuit is separate from any other serial data circuit on the vehicle. Accurate transmitting and receiving of serial data requires not only good circuit integrity but also adequate system voltage. This diagnostic test monitors the accuracy of the serial data transmitted between the TAC module and the PCM. If the PCM detects a loss of data or invalid data, this DTC sets.

Conditions for Running the DTC

    ? The ignition switch is in the crank or run position.
    ? The ignition voltage is more than 5.23 volts.

Conditions for Setting the DTC

    ? Invalid or missing serial data messages are detected for a predetermined amount of time.
    ? The above condition is met for more than 1 second.

Action Taken When the DTC Sets

    ? The control module illuminates the malfunction indicator lamp (MIL) when the diagnostic runs and fails.
    ? The control module records the operating conditions at the time the diagnostic fails. The control module stores this information in the Freeze Frame and/or the Failure Records.
    ? The control module commands the TAC system to operate in the Reduced Engine Power mode.
    ? A message center or an indicator displays Reduced Engine Power.
    ? Under certain conditions the control module commands the engine OFF.

Conditions for Clearing the MIL/DTC

  ? The control module turns OFF the malfunction indicator lamp (MIL) after 3 consecutive ignition cycles that the diagnostic runs and does not fail.
  ? A current DTC, Last Test Failed, clears when the diagnostic runs and passes.
  ? A history DTC clears after 40 consecutive warm-up cycles, if no failures are reported by this or any other emission related diagnostic.
  ? Clear the MIL and the DTC with a scan tool.

Diagnostic Aids

Important: Reprogramming the PCM may cause a communication error between the PCM and the TAC. If the PCM detects a communication error, DTC P1518 sets. Clear any DTCs from the memory that may have been set by Reprogramming.

    ? DTC P1518 sets if the battery voltage is low. If the customer's concern is slow cranking or no crank because battery voltage is low, ignore DTC P1518. Clear any DTCs from memory that may have set from the low battery voltage condition.
    ? DTC P1518 sets when there is a short to B+ on the TAC module ground circuit. Inspect the fuses for the circuits that are in the TAC module harness--i.e. cruise, brake. An inspection of the fuses may lead you to the circuit that is shorted to the TAC module ground circuit.
    ? DTC P1518 sets if the TAC module ignition feed circuit is shorted to a B+ supply circuit. The TAC module stays powered-up when the ignition switch is turned OFF. When the ignition switch is turned ON, the TAC module is powered-up before the PCM. DTC P1518 sets because no communication is detected by the TAC module from the PCM. Inspect related circuits for being shorted to a B+ supply circuit.
    ? Inspect the TAC module power and ground circuits and the TAC module/PCM serial data circuits for intermittent connections.
    ? Inspect the TAC module connectors for signs of water intrusion. If water intrusion occurs, multiple DTCs may set without any circuit or component conditions found during diagnostic testing.
    ? When the TAC module detects a problem within the TAC system, more than 1 TAC system related DTC may set. This is due to the many redundant tests run continuously on this system. Locating and repairing an individual condition may correct more than 1 DTC. Remember this if you review the stored information in Capture Info.
    ? For an intermittent condition, refer to Intermittent Conditions .

DTC P1514 (Brief, as all above)

Circuit Description

The powertrain control module (PCM) uses the following readings in order to calculate the predicted mass air flow (MAF) rate:
  ? The throttle position (TP)
  ? The barometric (BARO) pressure
  ? The intake air temperature (IAT)
  ? The engine RPM

The PCM compares the predicted MAF value to the actual MAF value, and to the speed density calculation in order to verify the proper throttle operation.

Conditions for Running the DTC

  ? DTCs P0601, P0602, P0604, P0606, P1515, P1516, P1517, or P1518 are not set.
  ? The following DTCs are not active at the same time: P1120, P1220, P1221
  ? The following DTCs are not active at the same time: P1120 and P1220
  ? The engine operates longer than 1 second.
  ? The engine speed is more than 500 RPM.
Conditions for Setting the DTC
  ? The PCM detects that the difference between the actual airflow (MAF) and the Speed Density calculated air flow is more than expected.
  ? The above condition is met for less than 1 second.

Action Taken When the DTC Sets

    ? The control module illuminates the malfunction indicator lamp (MIL) when the diagnostic runs and fails.
    ? The control module records the operating conditions at the time the diagnostic fails. The control module stores this information in the Freeze Frame and/or the Failure Records.
    ? The control module commands the TAC system to operate in the Reduced Engine Power mode.
    ? A message center or an indicator displays Reduced Engine Power.
    ? Under certain conditions the control module commands the engine OFF.

Conditions for Clearing the MIL/DTC

  ? The control module turns OFF the malfunction indicator lamp (MIL) after 3 consecutive ignition cycles that the diagnostic runs and does not fail.
  ? A current DTC, Last Test Failed, clears when the diagnostic runs and passes.
  ? A history DTC clears after 40 consecutive warm-up cycles, if no failures are reported by this or any other emission related diagnostic.
  ? Clear the MIL and the DTC with a scan tool.

Diagnostic Aids

  ? Inspect the throttle blade for being broken, bent, or missing.
  ? Inspect the throttle position (TP) sensor for proper installation. A sensor that is mis-aligned could set this DTC.
  ? Inspect the throttle actuator control (TAC) module connectors for signs of water intrusion. If water intrusion occurs, multiple DTCs may set without any circuit or component conditions found during diagnostic testing.
  ? Physically and visually inspect the throttle body assembly and correct any problems that you observe. Manually move the throttle blade from closedto wide open throttle (WOT). You should not need to use excess force.The throttle blade should move smoothly through the full range and then should independently return to a slightly open position.
  ? When the TAC module detects a condition within the TAC system, more than 1 TAC system related DTC may set. This is due to the many redundant tests run continuously on this system. Locating and repairing 1 individual condition may correct more than 1 DTC. Disconnecting components during testing may set additional DTCs. Remember this if you review the stored information in Capture Info.
  ? For an Intermittent condition, refer to Intermittent Conditions .

The powertrain control module (PCM) uses the following readings in order to calculate the predicted mass air flow (MAF) rate:
  ? The throttle position (TP)
  ? The barometric (BARO) pressure
  ? The intake air temperature (IAT)
  ? The engine RPM

The PCM compares the predicted MAF value to the actual MAF value, and to the speed density calculation in order to verify the proper throttle operation.

Conditions for Running the DTC

  ? DTCs P0601, P0602, P0604, P0606, P1515, P1516, P1517, or P1518 are not set.
  ? The following DTCs are not active at the same time: P1120, P1220, P1221
  ? The following DTCs are not active at the same time: P1120 and P1220
  ? The engine operates longer than 1 second.
  ? The engine speed is more than 500 RPM.

Conditions for Setting the DTC

  ? The PCM detects that the difference between the actual airflow (MAF) and the Speed Density calculated air flow is more than expected.
  ? The above condition is met for less than 1 second.

Action Taken When the DTC Sets

    ? The control module illuminates the malfunction indicator lamp (MIL) when the diagnostic runs and fails.
    ? The control module records the operating conditions at the time the diagnostic fails. The control module stores this information in the Freeze Frame and/or the Failure Records.
    ? The control module commands the TAC system to operate in the Reduced Engine Power mode.
    ? A message center or an indicator displays Reduced Engine Power.
    ? Under certain conditions the control module commands the engine OFF.

Conditions for Clearing the MIL/DTC

  ? The control module turns OFF the malfunction indicator lamp (MIL) after 3 consecutive ignition cycles that the diagnostic runs and does not fail.
  ? A current DTC, Last Test Failed, clears when the diagnostic runs and passes.
  ? A history DTC clears after 40 consecutive warm-up cycles, if no failures are reported by this or any other emission related diagnostic.
  ? Clear the MIL and the DTC with a scan tool.

Diagnostic Aids

  ? Inspect the throttle blade for being broken, bent, or missing.
  ? Inspect the throttle position (TP) sensor for proper installation. A sensor that is mis-aligned could set this DTC.
  ? Inspect the throttle actuator control (TAC) module connectors for signs of water intrusion. If water intrusion occurs, multiple DTCs may set without any circuit or component conditions found during diagnostic testing.
  ? Physically and visually inspect the throttle body assembly and correct any problems that you observe. Manually move the throttle blade from closedto wide open throttle (WOT). You should not need to use excess force.The throttle blade should move smoothly through the full range and then should independently return to a slightly open position.
  ? When the TAC module detects a condition within the TAC system, more than 1 TAC system related DTC may set. This is due to the many redundant tests run continuously on this system. Locating and repairing 1 individual condition may correct more than 1 DTC. Disconnecting components during testing may set additional DTCs. Remember this if you review the stored information in Capture Info.
  ? For an Intermittent condition, refer to Intermittent Conditions .

DTC P2135

Circuit Description

The throttle position (TP) sensors 1 and 2 are potentiometer type sensors each with three circuits:

    ? A 5-volt reference circuit
    ? A low reference circuit
    ? A signal circuit

The TP sensors are used to determine the throttle plate angle for various engine management systems. The control module provides each TP sensor a 5-volt reference circuit and a low reference circuit. The TP sensors then provide the control module with signal voltage proportional to throttle plate movement. Both TP sensor signal voltages are low at closed throttle and increase as the throttle opens. When the control module detects that TP sensor 1 signal and TP sensor 2 signals disagree or signal voltages are outside the predetermined range, this DTC sets.

Conditions for Running the DTC

    ? DTCs P1518 or P2108 not set.
    ? The ignition switch is in the crank or run position.
    ? The ignition voltage is more than 5.23 volts.

Conditions for Setting the DTC

    ? The TP sensor 2 disagrees with the TP sensor 1 by more than 7.5 percent.
    ? The above condition is present for more than 1 second.

Action Taken When the DTC Sets

    ? The control module illuminates the malfunction indicator lamp (MIL) when the diagnostic runs and fails.
    ? The control module records the operating conditions at the time the diagnostic fails. The control module stores this information in the Freeze Frame and/or the Failure Records.
    ? The control module commands the TAC system to operate in the Reduced Engine Power mode.
    ? A message center or an indicator displays Reduced Engine Power.
    ? Under certain conditions the control module commands the engine OFF.

Conditions for Clearing the MIL/DTC

  ? The control module turns OFF the malfunction indicator lamp (MIL) after 3 consecutive ignition cycles that the diagnostic runs and does not fail.
  ? A current DTC, Last Test Failed, clears when the diagnostic runs and passes.
  ? A history DTC clears after 40 consecutive warm-up cycles, if no failures are reported by this or any other emission related diagnostic.
  ? Clear the MIL and the DTC with a scan tool.

Diagnostic Aids

    ? Inspect the throttle actuator control (TAC) module connectors for signs of water intrusion. If water intrusion occurs, multiple DTCs may set without any circuit or component conditions found during diagnostic testing.
    ? When the TAC module detects a condition within the TAC system, more than 1 TAC system related DTC may set. This is due to the many redundant tests run continuously on this system. Locating and repairing 1 individual condition may correct more than 1 DTC. Disconnecting components during testing may set additional DTCs. Remember this if you review the stored information in Capture Info.
    ? If this DTC is determined to be intermittent, refer to Intermittent Conditions .

Whew!

All that sounds like a connector, or a TP/TPS pot opened up. And it may even be just  the ign sw, as stated earlier..

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Holy crap.....thanks for all that stuff.  I'm wondering though if you could decifer some of the stuff for me. Like what DTC means and are the different P#### error readings from I diagnostic tester? 

Thanks Again for all the help.
I really appreciate it.

DTC is simply Diagnostic Trouble code(s)

Those starting in "P" are powertrain.

It's apparent you have a problem with yout throttle position sensor, or the Thtottle actuator sensor. These have to track.

Except for early 02 Av's, the throttle is electrically controlled. These devices check each other via the  computer, in order to maintain some safety, as well as air & fuel demand variations.

If you connect a diagnostic tester, just translate what it displays to what is says above.

If it isn't there, then refer to this: 03 DTC Code list.

Hello All.

Just purchased 2004 z71 av. w/ 9k miles on it.  Did not even make it home when 'reduced engine speed' happened.

Dealer thought maybe throttle body problem.(via telephone)  Brought to another dealer (closer to home)  Codes p2101, p2135, p0120 stored. pip3089. Tech updated program.  Also found possible spread connector at circuit 581.

Found vehicle history of replaced throttle body unit @ 4700 miles. Towed in at 5400 miles and replaced electronic throttle control module.

Is this a hidden recuring problem that will be a safety issue for me and my family?  Does anyone have a handle on a proper and permaneant fix, or have I just bought someone elses problem that will now be mine? 

Only have a few more hours in which to give it back (Not that I want to, but I don't want a dangerous, unpredictable lemon either)

Urgent, please help.

e-mail  gmove20@yahoo.com

Thanks All!

gmove said:

Hello All.

Just purchased 2004 z71 av. w/ 9k miles on it.? Did not even make it home when 'reduced engine speed' happened.

Dealer thought maybe throttle body problem.(via telephone)? Brought to another dealer (closer to home)? Codes p2101, p2135, p0120 stored. pip3089. Tech updated program.? Also found possible spread connector at circuit 581.

Found vehicle history of replaced throttle body unit @ 4700 miles. Towed in at 5400 miles and replaced electronic throttle control module.

Is this a hidden recuring problem that will be a safety issue for me and my family?? Does anyone have a handle on a proper and permaneant fix, or have I just bought someone elses problem that will now be mine??

Only have a few more hours in which to give it back (Not that I want to, but I don't want a dangerous, unpredictable lemon either)

Urgent, please help.

e-mail? gmove20@yahoo.com

Thanks All!

Click to expand...

give it back and start over.  there are pleny of Av out there to choose from.

Sperry, you are a wealth of information! 

Service guy at purchased dealer tells me it is 'a simple little coolant sensor'.

Work for any of you?

Thanks....Gmove

If I bought a vehicle and anything happened that required it to be in the shop, I'd take it back...especially if I was depending on this vehicle for my family.  Thats just my opinion.

I would take it back or if you really want the truck take it back and tell them to call you when it is fixed and then let you start the initial purchase period over. Every dealer is different but many offer a 3 day 500 mile type no questions asked. Have them extend what ever they offer to begin from when you pick it up after getting this fixed. Any good dealer would do this. It's not like they are going to have to fork out the cash to fix it. It is under the original 3/36 warranty so it will be turned into Gm. I'm sure they would want to save the deal.

I can see your concern as it has been in before with the same issue. It appears to be a possible buy back vehicle or possibly even worse a Katrina vehicle. If I were you I would take it back if they won't work with you.