Cold Advance System Electrical Check

Cold Advance System Circuit:

Circuit Description:
With the key "ON," and coolant temperature below 80°F, the ECM grounds CKT 905 to the cold advance relay. Grounding CKT 905 turns "ON" the relay, to supply 12 volts to the cold advance solenoid, in the injection pump, and the glow plug controller The cold advance solenoid is now energized, which causes the injection timing to be advanced approximately 4°.

Cold Advance System Diagnostic Chart:

Test Description:
Number(s) below refer to circled number(s) on the diagnostic chart.

1. This step will determine if the problem is electrical or a malfunction inside the injection pump.

2. This step will determine if the ECM is able to turn "ON" the cold advance relay.

3. This step will determine if all factors are available for the cold advance relay to operate.


Diagnostic Aids:
- If there is no electrical problem found, check the operation of the cold advance solenoid in the injection pump. Refer to Diagnosis, Testing and Inspection Procedures.

- Before replacing ECM, use an ohmmeter and check the resistance of each ECM controlled relay and solenoid coil. Electrical Diagramsfor coil terminal I.D. of solenoid(s) and relay(s) to be checked. Replace any solenoid where resistance measures less than 20 ohms.