Check out this bulletin from GM about the concern you have. The connector in question is located under the driver's door where the wiring passes thru to underneath. If those connections show no signs of corrosion and are clean and tight suspect the actuator located on the rear differential.

#PIP4157: All Wheel Drive Disable Lamp On - keywords AWD inoperative light MIL - (Jun 19, 2007)


Subject: All Wheel Drive Disable Lamp On


Models: 2002-2006 Buick Rendezvous

2005-2006 Buick Terraza

2002-2005 Chevrolet Venture

2005-2006 Chevrolet Uplander

2002-2003 Oldsmobile Silhouette

2001-2005 Pontiac Aztek

2002-2005 Pontiac Montana

2005-2006 Pontiac Montana SV6

2005-2006 Saturn Relay

Equipped With All Wheel Drive (AWD)




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The following diagnosis might be helpful if the vehicle exhibits the symptom(s) described in this PI.

Condition/Concern:
Customer may comment on an all wheel drive (AWD) disable lamp on, technician may find no codes in any module.

Recommendation/Instructions:
If eSI diagnostics do not lead to a resolution inspect connector C305 and C305B at the body pass through for corrosion, if no corrosion is found suspect the differential clutch pump actuator check valve as the possible cause.

Please follow this diagnostic or repair process thoroughly and complete each step. If the condition exhibited is resolved without completing every step, the remaining steps do not need to be performed.