For 1990-2009 cars

Step | Action | Value(s) | Yes | No
--- | --- | --- | --- | ---
DEFINITION: The VOLT indicator or CHECK GAGES message with the engine outline telltale is inoperative.
1 | Inspect the indicator lamp bulb. Is the bulb OK? | -- | Go to Step 2 | Go to Step 3
2 | Turn ON the ignition. Backprobe the RED PCM C2 terminal 16 using an unpowered test light to B+. Does the test light go on? | -- | Go to Step 4 | Go to Step 5
3 | Replace the bulb. Are the repairs complete? | -- | System OK | --
4 | Backprobe the instrument cluster circuit 25 BRN wire using an unpowered test light to B+. Refer to Section 8A for the terminal number of the corresponding instrument cluster. Does the test light go on? | -- | Go to Step 6 | Go to Step 7
5 | Inspect the contact at PCM C2. If OK, diagnose the PCM output. Refer to Engine Controls . Repair as needed. Are the repairs complete? | -- | System OK | --
6 | Refer to the Section 8A for a complete electrical system diagnosis. Repair as needed. Are the repairs complete? | -- | System OK | --
7 | Inspect the BRN 25 wiring to the PCM for an open. Inspect the C200 terminal C4. Refer to Section 8A. Repair as needed. Are the repairs complete? | -- | System OK | --

Oldsmobile vehicles with gauge cluster UH8 or U2A receive change light input via Uart Dataline. Refer to Section 8A for diagnosis.