Test Description

WARNING: This page is about a different car, the 2002 GMC Sierra, 2002 GMC Cab & Chassis Sierra, 2002 Chevrolet Silverado, and 2002 Chevrolet Cab & Chassis Silverado. However, it is still accessible from the selected car via links, so may be relevant.

The numbers below refer to the step numbers on the diagnostic table.

2) - By disconnecting the VCU you can check the three wire bus supply and carrier voltages supplied by the VIU.
3) - By disconnecting the VCU you can check the three wire bus supply and carrier voltages supplied by the VIU.

Fig 1: DTC U1500 Diagnosis (Steps 1-6)

Courtesy of GENERAL MOTORS CORP.

Fig 2: DTC U1500 Diagnosis (Steps 7-12)

Courtesy of GENERAL MOTORS CORP.