K 1500 Truck 4WD V8-4.8L VIN V (2003)
Control Module: Customer Interest
Drivetrain - 4X4 Inoperative/Lamp Flashing/DTC's Set
Bulletin No.: 03-04-21-001D
Date: December 04, 2003
TECHNICAL
Subject:
4WD Switch Indicator Lights Flashing, 4WD Inoperative, DTCs C0327, P0500, P0836, P1875 Set (Replace Encoder Motor Sensor, Reprogram TCCM,
Inspect Front Drive Axle Engagement Sleeve for Damage/Repair if Necessary)
Models:
2003 Chevrolet Avalanche, Silverado, Suburban, Tahoe
2003 GMC Sierra, Yukon, Yukon XL
with 4WD and Electric Shift or Active Transfer Case (RPO NP1 or NP8)
Supercede:
This bulletin is being revised to update the Diagnosis and Correction Information and to change two part numbers. Please discard Corporate Bulletin
Number 03-04-21-001C (Section 04 - Driveline/Axle).
Condition
Some customers may comment that the Service 4WD light is on, the 4WD system is inoperative, the 4WD switch indicator lights are blinking or that a
grinding noise is heard from the front axle.
Service Diagnosis
Technicians may find DTC C0327 in the Transfer Case Control Module (TCCM) and/or DTC P0836 in the Transmission Control Module (TCM) and/or
DTC P0500 and P1875 in the Powertrain Control Module (PCM).
It is possible that the module may be in a mode that will not allow any shifts or updates for the software or calibrations. If this occurs, the TREC fuse (in
the engine compartment) must be pulled and reinstalled after 30 seconds. This should allow further operation and service of the system. If a C0550 code
is found, this is an unrelated concern and SI diagnostics should be followed for this concern.
Correction
Important:
For ease of reassembly, shift the transfer case assembly to 2H1 for the NV263 (NPI), or Neutral for the NV246 (NP8) prior to removing any
components. For information on placing the NV246 (NP8) transfer case in NEUTRAL, see the procedure shown in this bulletin.
1.
Remove the transfer case and front axle/engine skid plates (if equipped).
2.
Disconnect and position the front propeller shaft aside.
3.
Disconnect the transfer case encoder motor wiring harness.
