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Service 4WD issue resolved- and how to know if yours is a software issue

TuffysTruck said:
DrX,

I'm not getting any DTCs that are 4WD related. I am working through knock sensor codes, and O2 sensor issues, but both are unrelated to this issue.

Based on the diagnostic from the dealer they are saying it's the TCCM. Can I run a diagnostic myself using a multi-meter to determine if the switch is bad before proceeding with the TCCM replacement?

I'm looking at buying the DORMAN 599114 {#12590219} 4WD; Electronic Shift (NP:cool:; Four Button Selection Switch for $140.79 and a core charge of $223.00 from RockAuto.  The switch is half the price of the TCCM.

Since this one is the NP8 build code I should be able to just plug and play, right?

Thanks,

Yes, the individual buttons just change the overall resistance through the switch:
https://www.youtube.com/watch?v=JNWxhIWs8Uk

A new switch would be plug n play.

You may not be able to read TCCM DTCs wothout a commercial type or GM scan tool.
 
The (DORMAN 599114) I listed above is the TCCM.

Its the TCCM for the 4 button selector hence the description. My question about plug and play was if the (DORMAN 599114) TCCM should be plug and play since it is a NP8 build code?

I'll definitely run through that video and check out the switch box before proceeding to the TCCM.
 
TuffysTruck said:
The (DORMAN 599114) I listed above is the TCCM.

Its the TCCM for the 4 button selector hence the description. My question about plug and play was if the (DORMAN 599114) TCCM should be plug and play since it is a NP8 build code?

I'll definitely run through that video and check out the switch box before proceeding to the TCCM.

The part description says pre-programmed, so it should be plug n play:
https://www.summitracing.com/int/parts/rnb-599-114/overview/
 
Switch tested out in spec. The lights behind the buttons go in an out though. Put it back in and tested all setting stationary, I could here the TC shifting in and out of the different settings. Every other time I selected something it may or may not do it, but I know the switch is sending out the right signals, it's gotta be the TCCM.

I'll update when I order and install the new one. Thank you for your help!
 
So did that new TCCM do the trick?
I'm finding myself in a similar mess. Replaced the transfer case switch a couple weeks ago. All was well until today. Now it's showing no lights, says service 4wd. I really don't feel like getting hosed by a dealership for a repair.
 
Everything seems to be operating fine for now 'fingers crossed', and I'm working on replacing knock sensors this weekend so I haven't ordered the TCCM from Rockauto yet. From what I've gathered from this thread as long as the build code on the TCCM matches your existing it should be plug and play. When I get around to fixing it I will provide an update. Good Luck!
 
I know this is like beating a dead horse but this is ridiculous. I've been experiencing this same thing for the last 5 years. I've replaced the encoder motor three times and all is good for about a month. Replaced the switch and nothing changed. Took it to an indy for the rear end and asked him about it and he said it sounded like the TCCM. Replaced that recently and I got the same issues. :E:
I've even checked the grounds and cleaned them all! I guess it's time to go to the dreaded dealer!!
 
This is the only TSB that comes up in my eSI service manual:

Service 4WD Indicator Illuminated, DTC B2725 Set (Replace Transfer Case Shift Control Switch) #02-04-21-004 - (Apr 15, 2002)
"Service 4WD" Indicator Illuminated, DTC B2725 Set (Replace Transfer Case Shift Control Switch)
1999-2002 Chevrolet and GMC C/K Pickup and Utility Models (Silverado, Sierra, Avalanche, Suburban, Tahoe, Yukon, Yukon XL)

with Four Wheel Drive and NVG 236/246 Transfer Case (RPO NP:cool:

Condition
Some customers may comment on the Service 4WD indicator illuminating. Upon investigation, the technician may find DTC B2725 set.

Cause
The condition may be due to a intermittent fault in the transfer case shift control switch.

Correction

Important
The transfer case shift control module should not need replacement. DO NOT replace P/N 15749703 unless diagnosis points to the module as the malfunction.


Replace the transfer case shift control switch using published Service Information procedures.

Parts Information
Part Number
Description

15709327
Transfer Case Shift Control Switch


Parts are currently available from GMSPO.

Warranty Information
For vehicles repaired under warranty, use:

Labor Operation
Description
Labor Time

K4123
Switch, Transfer Case Select - Replace
Use published labor operation time
Is it OK to drive my truck if the tec fuse is blown?
 
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