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.

3) - This step tests for a voltage signal from the PCM.
4) - This step tests for a missing or erratic vehicle speed signal from the PCM. An assistant may be required to perform this test.

Fig 1: DTC C0235-C0237 or P1504 Diagnosis (Steps 1-3)

Courtesy of GENERAL MOTORS CORP.

Fig 2: DTC C0235-C0237 or P1504 Diagnosis (Steps 4-10)

Courtesy of GENERAL MOTORS CORP.