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  • avatar karjunkie 05/08/09 12:01 pm PST

    There are a couple of TSBs on this as follows:

    Service 4WD Indicator Illuminated, DTC B2725 Set, Transfer Case Selector Switch is in One Position - Indicator Lamp Indicates Another Range Is Selected (Replace Transfer Case Shift Control Switch) #02-04-21-002A - (02/11/2003)

    Part Number 15194913
    Switch, Transfer Case Shift Control
    Qty 1

    ---------------------
    and...

    Inoperative 4WD/AWD Lamps, Inoperative 4WD/AWD System (Reprogram Transfer Case Control Module) #02-04-21-006B - (08/18/2003)
    with Electronic Shift or Active Transfer Case (RPO NP1, NP4 or NP8)

    Correction
    Remove the underhood (ATCM or TREC) TCCM fuse.
    Wait 30 seconds.
    Reinstall the fuse. The module should "wake up" and communicate with the Tech 2®.
    Check for codes in the TCCM. If a C0550 is found, replace the module and go to the next step.
    Reprogram the TCCM using normal procedures...

    ---------------------

    Try removing the fuse as per the 2nd TSB to see if that helps. The 2nd TSB includes all 2002-03 GM T360/370s (TB, Envoy, Bravada) full-size pickups, and the Tahoe/Suburban too. Bascially anything w/ an electronic t-case.

Answers

  • karjunkie 05/08/09 12:01 pm PST

    There are a couple of TSBs on this as follows:

    Service 4WD Indicator Illuminated, DTC B2725 Set, Transfer Case Selector Switch is in One Position - Indicator Lamp Indicates Another Range Is Selected (Replace Transfer Case Shift Control Switch) #02-04-21-002A - (02/11/2003)

    Part Number 15194913
    Switch, Transfer Case Shift Control
    Qty 1

    ---------------------
    and...

    Inoperative 4WD/AWD Lamps, Inoperative 4WD/AWD System (Reprogram Transfer Case Control Module) #02-04-21-006B - (08/18/2003)
    with Electronic Shift or Active Transfer Case (RPO NP1, NP4 or NP8)

    Correction
    Remove the underhood (ATCM or TREC) TCCM fuse.
    Wait 30 seconds.
    Reinstall the fuse. The module should "wake up" and communicate with the Tech 2®.
    Check for codes in the TCCM. If a C0550 is found, replace the module and go to the next step.
    Reprogram the TCCM using normal procedures...

    ---------------------

    Try removing the fuse as per the 2nd TSB to see if that helps. The 2nd TSB includes all 2002-03 GM T360/370s (TB, Envoy, Bravada) full-size pickups, and the Tahoe/Suburban too. Bascially anything w/ an electronic t-case.

  • djm1951 05/08/09 12:28 pm PST

    Thank you for the answer. I will definitely check this out this weekend. I have had the codes ran and there were none that showed up.

  • djm1951 05/08/09 1:35 pm PST

    I looked at the fuse box. These is nothing listed as ATCM, TREC or TCCM fuse. Is there another name for it?

  • greco5 01/10/10 10:19 pm PST

    My 2005 GMC Envoy 5.2L when I switch the 4X4 selector switch from 2W to any of the 4 wheel selections there is no change. Also the lights on the selector switch are not lighting up in any of the positions. Everything had been working fine, till the other day when my wife started the truck to go somewhere.

  • cntinuum 01/16/10 11:28 pm PST

    The fuse to pull to do the test is #8. This topic is discussed a lot on the trailvoy.com forum. http://forums.trailvoy.com/showthread.p
    h...
    is a link into a thread discussing this. Good luck. Dave

    Source: http://forums.trailvoy.com/

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