Test Procedures

WARNING: This page is about a different car, the 1991 Cadillac Fleetwood and 1991 Cadillac DeVille. However, it is still accessible from the selected car via links, so may be relevant.

NOTE: Test numbers refer to test numbers on diagnostic chart.

A 2-second bulb check of SERVICE AIR COND light with key on and after crank, confirms battery, ignition and ground integrity to the BCM.
Verifies proper operation of the COOLANT TEMP and SERVICE ENGINE SOON light.
A 2-second bulb check of the SERVICE ENGINE SOON light verifies battery, ignition and ground integrity to the PCM.
The Electronic Climate Control Panel (ECCP) and Fuel Data Center (FDC) must be functional in order to use the self-diagnostic system. Check if panels illuminate and respond when buttons are depressed.
After entering diagnostics, record all displayed trouble codes and note those displayed during both the first and second pass.

Fig 1: Flow Chart, Self-Diagnostic System Check