Cold Advance Solenoid: Testing and Inspection

Fig. 35 Cold Advance Control (CAC) Circuit schematic. 1983-87 V8-379 diesel:

1983-87 V8-379

1. Check ignition 1 fuse and replace if blown. If fuse blows again, check for short in power feed circuit, Fig. 35.
2. Ensure that engine temperature is less than 95° F., connect test lamp between CAC solenoid connector terminal and ground leaving connector connected, then switch on ignition.
3. If test lamp fails to light, proceed to step 8. If lamp lights, start engine and observe test lamp and engine RPM.
4. If test lamp remains on for 35 seconds, then goes out with an attendant drop in engine RPM, system is operating properly.
5. If test lamp remains on for 35 seconds, then goes out, but engine RPM does not drop, CAC solenoid is defective.
6. If lamp does not light with engine running, or if lamp lights but does not go out after 35 seconds, stop engine, disconnect electrical connector from CAC relay and connect test lamp between terminals A and G in harness connector, Fig. 35.
7. Start engine and observe test lamp. If lamp lights, CAC relay is defective; if lamp does not light, check for open in relay ground circuit or signal circuit between relay and alternator.
8. If test lamp did not light in step 2, disconnect electrical connector from temperature switch and connect jumper wire across connector terminals.
9. Switch ignition on and connect test lamp between CAC relay terminal A, Fig. 35.
10. If test lamp lights, temperature switch is defective; if lamp does not light, check for open if feed circuit to temperature switch or in circuit between switch and relay.