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Trailer Brake Relay

JustinMcLaren

New Member
Joined
Sep 16, 2019
Messages
2
I?m trying to locate the trailer Brake Relay on my 2009 Avalanche. I?ve crawled around underneath and above spare tire and I?ve had no luck locating it thus far.  It?s driving me mad I tell you. I appreciate any help anyone can offer.
 
Did you drop the spare? Follow the trailer wiring back, should be tucked up above the frame above the spare tire.
https://youtu.be/KKsYbN6_eZY
https://www.youtube.com/watch?v=DPQNekkbD-4

Probably looks something like this
https://www.amazon.com/ACDelco-20904439-Original-Equipment-Continue/dp/B00559VPK0/
 
I?ve been all through underneath there. Traced the wire which led me to speed sensors on each side. There?s a gas tank vapour canister there. I?ve watched both those videos you posted and the part you posted is the one I ordered. It?s got to be there somewhere. But not where the YouTube videos show it to be on other trucks. Thanks for your effort.
 
Hmm... Looking through the service manual and gmpartscenter.net now but I do not see a diagram that lists that part... What error or problem are you getting exactly? Is it 'Check Trailer Wiring' ??

A little extra info about the system below in case it helps, but it doesn't show the location:

The trailer brake control relay receives inputs from the trailer brake control module (TBCM), these inputs are used to determine the amount of voltage the relay will supply to the trailer brakes.

Conditions for Running the DTC

Ignition ON.
Battery voltage is 9.5-17 volts.
The module is powered up and completes initialization.
Conditions for Setting the DTC

C0870 00

The TBCM circuit reference voltage for the trailer brake control relay is below 4.8 volts or above 5.2 volts.
C1112 00

The TBCM detects a short to ground, open or a short to voltage on the integrated trailer brake relay control active low circuit.
The TBCM detects an open in the battery positive voltage circuit to the trailer brake control relay.
The TBCM detects an open in the ground circuit to the trailer brake control relay.
The TBCM detects a short to ground or open in the solid state relay enable circuit.
C1113 01

The TBCM detects a short to voltage in the solid state relay enable circuit.
The TBCM detects a short to voltage in the trailer brake output supply voltage control circuit.
C1114 00

The TBCM detects a short to ground, open or a short to voltage on the solid state relay output circuit.
C1119 00

The TBCM detects a short to ground, open or a short to voltage on the relay feedback circuit.
Action Taken When the DTC Sets


The trailer brake control will be disabled for the remainder of the ignition cycle.
The driver information center will display Service Trailer Brake System.
Conditions for Clearing the DTC


The condition for the DTC is no longer present.
The TBCM clears the history DTC when a current DTC is not detected in 40 consecutive drive cycles.
Circuit/System Verification

Important: These diagnostics are based on having no trailer connected.

Ignition ON, observe the scan tool trailer brake controls user gain parameter. The reading should be between 0-100 percent, and change with operating the gain switch up or gain switch down.

Circuit/System Testing

Important: These diagnostics are based on having no trailer connected.


Ignition OFF, disconnect the harness connector at the solid state relay.
Test for less than 5 of resistance between the ground circuit terminal B and ground.
If greater than the specified range, test the ground circuit for an open/high resistance.
Ignition OFF, verify that a test lamp illuminates between the B+ circuit terminal F and ground.
If the test lamp does not illuminate, test the B+ circuit for a short to ground or an open/high resistance. If the circuit tests normal and the STUD 2 fuse is open, replace the trailer brake control relay.
Ignition ON, verify that a test lamp does not illuminate between control circuit terminal E and ground.
If test lamp illuminates, test the control circuit for a short to voltage. If the circuit tests normal, replace the TBCM.
Ignition ON, verify that a test lamp does not illuminate between control circuit terminal E and B+.
If test lamp illuminates, test the control circuit for a short to ground. If the circuit tests normal, replace the TBCM.
Ignition ON, test for 3.2-4.1 V between the control circuit terminal C and ground.
If less than the specified range, test the control circuit for a short to ground or an open/high resistance. If the circuit tests normal, replace the TBCM.
If greater than the specified range, test the control circuit for a short to voltage. If the circuit tests normal, replace the TBCM.
Ignition ON, test for 3.2-4.1 V between the control circuit terminal A and ground.
If less than the specified range, test the control circuit for a short to ground or an open/high resistance. If the circuit tests normal, replace the TBCM.
If greater than the specified range, test the control circuit for a short to voltage. If the circuit tests normal, replace the TBCM.
Ignition ON, test for less than 1 V between the control circuit terminal D and ground.
If greater than the specified range, test the control circuit for a short to voltage. If the circuit tests normal, replace the TBCM.
If all circuits test normal, replace the trailer brake solid state relay.

AND:

# PIT4366G: Check Trailer Wiring Message Displayed On DIC - (Aug 7, 2014)
Subject: Check Trailer Wiring Message Displayed On DIC Models: 2009 - 2013 Chevrolet Avalanche 2009 - 2014 Chevrolet Suburban, Tahoe 2007 - 2013 Chevrolet Silverado 2014 Chevrolet Silverado 2500/3500 2007 - 2013 GMC Sierra 2014 GMC Sierra 2500/3500 2009 - 2014 GMC Yukon Models With Integrated Trailer Brake Controller (RPO JL1) The following diagnosis might be helpful if the vehicle exhibits the symptom(s) described in this PI.
Condition/Concern
Some customers may experience an intermittent "Check Trailer Wiring" message in vehicles equipped with ITBC (Integrated Trailer Brake Controller) RPO JL1 and no DTC's stored.
Below are two possible causes for this concern:
1. This message may be displayed each time the trailer's running lamps, turn signal lamps, or brake lamps are turned on, especially if the trailer is equipped with a large number of lamps. This condition is most likely caused by insufficient trailer grounding and the trailer ground wiring will need to be repaired and/or upgraded. 2. This concern could be caused by a poor connection at the 7-way trailer connector. There are several manufacturers of 7-way (trailer side) connectors and many do not comply with the SAE standard specifications. Some 7-way (trailer side) connector plugs may not properly engage the truck's 7-way connector socket and cause open circuits. Also, they may cause deformation and excessive wear of the terminals on the truck's 7-way connector socket. Over time this will lead to poor terminal tension between the 7-way (trailer side) connector plug and the truck's 7-way connector socket. Since the Trailer Brake Control Module is always monitoring the vehicle and trailer circuits/components, a poor connection at the 7-way connector can cause a "Check Trailer Wiring" message on the DIC. Recommendation/Instructions
1. Inspect and clean the ground wire (normally white wire) connection on the trailer side of the 7-pin connector. ^ Make sure that the wires inside the trailer side connector are clean and securely fastened ^ If an electrical junction box exists on the trailer, make sure the wires inside the junction box are clean and securely fastened. ^ Once this procedure is complete, check to see if the condition has been corrected. If the condition still exists, perform the following procedure: 1.1 Remove the original trailer ground wire (normally white wire) from the trailer side of the 7-pin trailer connector.
1.2 Install a ring terminal (PN 12103512 or equivalent) to this wire and fasten the ring terminal to the metal or aluminum chassis of the trailer using an M6x1x20 self taping phosphate zinc coated screw (PN 11515925 or equivalent).
^ Pre-drill trailer chassis location with a 3/16" hole. ^ Make sure the trailer chassis location is clean of paint or coating material prior to installation. ^ Galvanic corrosion between dissimilar trailer and screw metals may require that this ground location be periodically cleaned. 1.3 Obtain a sufficient length of minimum 10 gauge (5.0 mm) white wire and fasten with ring terminal (PN 12103512 or equivalent) to the trailer chassis at the same location as the original ground wire.
1.4 Install and fasten the other end of the new ground wire into the trailer side of the 7-pin trailer connector
1.5 Install conduit on the original and new trailer ground wires and secure the conduit to the existing trailer harness.
2. Engineering has recommended the use of Pollak Heavy Duty 7-Way (Trailer Side) Connector Plugs. Pollak is the OEM manufacturer of the truck's 7-way connector socket; by using a Pollak Heavy Duty 7-Way (Trailer Side) Connector Plug will ensure proper fit when the two connectors are mated. Pollak's website is: Electrical Connectors, Electrical Switches & Electrical Sensors: Pollak. Once at the home page select "Connectors" and then "Heavy Duty 7-Way Plugs and Accessories". Note : If the truck's 7-way connector socket terminals are deformed or have excessive wear, it will be necessary to replace the truck side connector (with a GM CCA Customer Care and After sales Part) along with the trailer's 7-way connector plug to a Pollak HD.
 
Page A-62, part #3. Tucked in the drivers side inner frame rail. Is your relay here?
https://www.gmupfitter.com/files/media/photo/477/2009_LD_ElectricalPickupsChassisCabs_100813.pdf

Do you have the trailering package with the optional transmission cooler?

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Are you sure you have that option, it's not part of a trailer towing package.

Take a look at the sticker on the glove-box door and look for RPO code JL1
 
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