EFE Relay: Testing and Inspection

To test the Cold Mixture Heater Relay, located in the engine compartment on the passenger side firewall, proceed as follows .

1. The engine coolant temperature must be below 60°C (140°F).

2. Disconnect the cold mixture heater (located between the carburetor and the intake manifold) from the wiring harness (connector M80, refer to ELECTRICAL AND ELECTRONIC DIAGRAMS) and connect a voltmeter between the two terminals of the body harness.
3. Turn the ignition switch "on" and start the engine. The voltmeter should read battery voltage.
4. Allow the engine to warm to a temperature above 60°C (140°F), the voltmeter reading should drop to 0 volts as the relay opens. This would indicate proper operation.

ECU Pin Connectors:

5. If the Relay does not open at the proper time (engine temperature), test pin B-1 on the ECU connector, to determine if the ECU is providing a ground.
6. If there is continuity to ground at pin B-1, and the Relay has still not opened, then the relay is faulty.
7. If there is NO continuity to ground, then either the ECU, the wiring harness, or the coolant temperature sensor is at fault.
8. Test the coolant temperature sensor signal to the ECU before replacing the ECU.