ECM Power Circuits Check
- Disconnect ECM coupler. Turn ignition on, but do not start engine. Connect voltmeter between terminal No. 19 of disconnected coupler (on wiring harness side) and body ground. See Fig 1
. Check voltage.
Courtesy of GENERAL MOTORS CORP.
- Repeat voltage check for terminal Nos. 20, 23, 24, 26, 1 and 10. If measured voltage between each terminal and body is about 12 volts, each circuit is in good condition.
- Check clutch switch operation as follows: Connect voltmeter between terminal No. 26 and ground. Depress clutch pedal fully. Voltage should drop to zero, indicating clutch switch is on and terminal is grounded. Reconnect coupler to ECM.