Test Description

WARNING: This page is about a different car, the 2003 Pontiac Aztek and 2003 Buick Rendezvous. 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 - Listen for an audible click when the RAP operates. Command both the ON and OFF states. Repeat the commands as necessary.
3 - Verifies that the BCM is providing voltage to the RAP relay.
4 - Tests for an open in the ground circuit to the RAP relay.
5 - Tests if voltage is constantly being applied to the RAP relay.

Fig 1: DTC B1478 Diagnosis (Steps 1-3)

Courtesy of GENERAL MOTORS CORP.

Fig 2: DTC B1478 Diagnosis (Steps 4-12)

Courtesy of GENERAL MOTORS CORP.