Main Relay (Computer/Fuel System): Testing and Inspection

Fig. 18 ECU connector pin # 8:

Fig. 19 ECU relay:

1. Remove connector from ECU
2. Connect the tachymetric bypass harness and activate switch.
3. Connect a voltmeter between pin 8 of the connector, Fig. 18, and the vehicle ground. Voltage reading should be above 12 volts.
4. If incorrect, check the operation of the ECU relay (M748), Fig. 19, and the electrical circuit continuity.