Self-Diagnostic System: Description: Notes

WARNING: This page is about a different car, the 2000 Cadillac Seville, 2000 Cadillac Eldorado, and 2000 Cadillac DeVille. However, it is still accessible from the selected car via links, so may be relevant.

PCM is equipped with a self-diagnostic system which detects system failures or abnormalities. When a malfunction occurs, PCM will store a Diagnostic Trouble Code (DTC) and, in most cases, illuminate the Malfunction Indicator Light (MIL) located on instrument cluster. Malfunctions are recorded as hard failures or intermittent failures.

There are 4 types of DTC categories:

Type "A"

Emissions related. Illuminates MIL the first time DTC sets.

Type "B"

Emissions related. Illuminates MIL if fault is active for 2 trips. A trip may consist of only a key cycle to power up PCM, allow the diagnostic to run, then cycle the key off to power down the PCM.

Type "C"

Non-emissions related. Does not illuminate MIL, but will illuminate SERVICE light.

Type "D"

Non-emissions related. Does not illuminate MIL or SERVICE light.