Transfer Case Control Module - 4WD Lamp ON/DTC'S Set
File In Section: 04 - Driveline AxleBulletin No.: 03-04-21-005
Date: June, 2003
TECHNICAL
Subject:
Service 4WD Light On, 4WD Inoperative, Diagnostic Trouble Codes (DTC) C0300 and/or C0305 Set (Reprogram Transfer Case Control Module (TCCM))
Models:
2003 Chevrolet Avalanche, Silverado, Suburban, Tahoe, TrailBlazer
2003 GMC Envoy, Sierra, Yukon, Yukon XL
2003 Oldsmobile Bravada with 4WD (RPOs NP4, NP8)
Condition
Some customers may comment that the Service 4WD light is on and/or the 4WD is inoperative.
Cause
Condition may be caused by a TCCM calibration issue.
Correction
Follow the service procedure below for diagnosis and repair of this condition.
1. With a scan tool, select the TCCM DTCs.
^ If TCCM DTCs C0300 or C0305 are present in the TCCM, continue with TCCM reprogramming in Step 2.
^ If TCCM DTC C0374 is present with any of the above codes, disregard and clear the DTC and continue with TCCM reprogramming in Step 2.
^ If TCCM DTC C0374 is present alone with none of the above listed codes, additional diagnosis is required. Refer to Service Information (SI) for proper diagnosis of the applicable vehicle.
^ If TCCM DTC C0550 is present, refer to DTC C0550 in SI for proper diagnosis of the applicable vehicle.
2. Clear all DTCs and reprogram the TCCM with TIS version 3.5 or newer released to the dealers on 3-22-03.
Warranty Information
For vehicles repaired under warranty, use the table.
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