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Billy, Chevrolet tecnician
Category: Chevy
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Experience:  Over 25 years experience,GM grand master for 8 years,certified smog and government safety inspector
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2002 Chevy Trailblazer: 4x4 stopped working..Indicator lights

Resolved Question:

2002 Chevy Trailblazer. 4x4 stopped working. Indicator lights on switch out.
Submitted: 5 years ago.
Category: Chevy
Expert:  Billy replied 5 years ago.
hello and welcome to just answer.

this bulletin could be related to this malfunction.

If you feel my answer was helpful, please click the ACCEPT button. Feedback & Bonuses are always welcome.
Best regards,
Billy.

#02-04-21-006E: Inoperative 4WD/AWD Lamps, Inoperative 4WD/AWD System, DTC C0550 Set No Communication with TCCM (Reprogram Transfer Case Control Module) - (Jul 20, 2006)
Subject:Inoperative 4WD/AWD Lamps, Inoperative 4WD/AWD System, DTC C0550 Set, No Communication with TCCM (Reprogram Transfer Case Control Module)
Models:2004 Buick Rainier
2002-2004 Chevrolet TrailBlazer, TrailBlazer EXT
2003-2004 Chevrolet Avalanche, Silverado, Suburban, Tahoe
2002-2004 GMC Envoy, Envoy XL
2003-2004 GMC Sierra, Yukon, Yukon XL
2004 GMC Envoy XUV
2002-2004 Oldsmobile Bravada
with Electronic Shift or Active Transfer Case (RPOs NP1, NP4 or NP8)


This bulletin is being revised to add Subject information and change the labor operation. This bulletin cancels and supersedes Bulletin Number 03-04-21-006. Please discard Corporate Bulletin Numbers 02-04-21-006D and 03-04-21-006 (Section 04 -- Driveline/Axle).


Condition

Some customers may comment that the 4WD/AWD indicator lights on the selector switch do not work, or the 4WD/AWD system may be inoperative and/or the service 4WD light is illuminated. The condition is typically intermittent and always occurs at key-up. Upon investigation, the technician may find DTC C0550 set.

Cause

The Transfer Case Control Module (TCCM) has not received the wake-up call during key-up and has remained in the "sleep mode".

When the TCCM is in the "sleep mode", it will not communicate with the class II bus or the Tech 2®.

Correction

  1. Try to communicate with the TCCM. If no communication, go to step 2. If communication is possible, go to step 5.
  2. Remove the underhood (ATCM or TREC) TCCM fuse.
  3. Wait 30 seconds.
  4. Reinstall the fuse. The module should "wake up" and communicate with the Tech 2®.
  5. Check for codes in the TCCM. If a C0550 is found current or in history with or without other codes, replace the module and go to step 6.
  6. Reprogram the TCCM with the latest TIS software using normal SPS procedures.
  7. Verify operation and that no codes are present.

Important: For the 2002 model year, the TCCM must be replaced and reprogrammed.

Customer: replied 5 years ago.
From your answer I tried some things including removing and replacing the fuse for the ATCM and the answer follows the symptoms. This is a 2002. The note in your answer states that 2002 must replace the TCCM. Do you know what this would cost to replace? Does this need to be done by a dealer, or can I go to any good mechanic?
Expert:  Billy replied 5 years ago.
hello again,

I,m sorry but I don't know the cost of the module. anyone can replace the module including yourself, however it must be reprogrammed otherwise it will not function. you will need to find someone or someplace who can do GM servcice programing.
Furthermore before you replace anything it would be wise to scan the system for codes and data as per the service bulletin. There might be some other trouble codes in the system that would have to be repaired first.
Also you should check for power at the fuse you have removed. it could be burnet out.


If you feel my answer was helpful, please click the ACCEPT button. Feedback & Bonuses are always welcome.
Best regards,
Billy.
Billy, Chevrolet tecnician
Category: Chevy
Satisfied Customers: 510
Experience: Over 25 years experience,GM grand master for 8 years,certified smog and government safety inspector
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