Electrical Load Sensor (Metro)

NOTE: Electrical load sensor may be referred to as diode module.

Warm engine to normal operating temperature. Turn ignition off and install tachometer. Start engine and note idle RPM. Turn on and off the headlights, stoplights, heater blower and rear defogger one at a time and note engine speed with each accessory on. Engine speed should increase when each component is turned on.
If engine speed does not increase, go to step 3). If engine speed increased with operation of each accessory, electrical load sensor is working okay. Ensure electrical connections at ECM and electrical load sensor are secure. ECM is located under left side of dash. The diode module is located behind instrument panel, near steering column. See Fig 1 .
Using voltmeter, backprobe Brown/White wire terminal A2 (M/T) or B12 (A/T) at ECM and ground. ECM is located under left side of dash. Turn on and off headlights, stoplights, heater blower and rear defogger one at a time. Battery voltage should be indicated when each accessory is turned on.
If battery voltage exists, check for loose connections at ECM or defective ECM. If battery voltage did not exist, check for open wiring circuit on appropriate accessory. See ACCESSORY WIRING COLOR . If wiring is okay, replace diode module.

ACCESSORY WIRING COLOR

Fig 1: Identifying Diode Module Location

Courtesy of GENERAL MOTORS CORP.