Hot Light Diagnosis

Hot light is powered by the 10-amp GAGES fuse. Light will turn on when ECM provides a ground for the circuit. If circuit grounds between light and ECM, light will illuminate any time the ignition is turned on.

1. Turn ignition on with engine off (bulb test position). If hot light illuminates, go to step 3. If hot light toes not illuminate, check the following:
   • 10-amp GAGES fuse
   • Faulty instrument cluster bulb
   • Open circuit between fuse and hot light
2. Backprobe terminal YE2 (A body) or YF2 (N body) at ECM with a test light to battery voltage. Turn ignition on. If test light does not illuminate, ECM terminal connection is bad or ECM is faulty. If test light illuminates, turn ignition off. Disconnect ECM connectors. Jumper terminal YE2 (A body) or YF2 (N body) to ground. Turn ignition on. If hot light does not illuminate, check for open circuit between hot light and ECM. If light does not illuminate and all circuits are intact and power is available to light, instrument cluster must be replaced.
3. Start engine. If test light goes off, no problem is evident. See DIAGNOSTIC AIDS. If test light is on, turn ignition off. Disconnect ECM connector. Probe ECM harness terminal YE2 (A body) or YF2 (N body) with a test light to battery voltage. If light is off, replace ECM. If light is on, repair short to ground in circuit No. 35. If no short is present, replace instrument cluster.

Fig 1: Code 26 Troubleshooting Flowchart 1 Of 2 (3.3L A & N Body)

Courtesy of GENERAL MOTORS CORP.

On vehicle with a 3T40 transmission, QDM A fault status on "Scan" tester should read HIGH until 2nd gear switch is closed or brake is applied. To simulate driving in 2nd gear and change status to LOW, disconnect TCC connector and connect test light between harness terminals A and D.

1. This step determines which circuit is out of specification.