Upshift Indicator Test: Lumina
- Disconnect Electronic Control Module (ECM) White connector "B". Turn ignition switch to RUN position. Using a voltmeter, measure voltage between ECM connector "B" (Tan/Black wire) and ground.
- If battery voltage is present, see appropriate article in the ENGINE PERFORMANCE Section for ECM diagnosis. If battery voltage is not present, check bulb and Tan/Black wire for open circuit or short to ground. If bulb and wire are okay, replace IPC.