Electrical Load Sensor (Metro)

Warm engine to normal operating temperature. Turn ignition off. Install tachometer. Start engine and note idle RPM. Individually turn headlights, stoplights, heater blower and rear defogger on and off, noting 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 increases with operation of each accessory, electrical load sensor is okay. Ensure electrical connections at ECM and electrical load sensor are secure. ECM is located under left side of dash. 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. Individually turn headlights, stoplights, heater blower and rear defogger on and off. 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 does not exist, check for open wiring circuit on appropriate accessory. See ACCESSORY WIRING COLOR table. If wiring is okay, replace diode module.

ACCESSORY WIRING COLOR

Fig 1: Diode Module Location

Courtesy of GENERAL MOTORS CORP.