Power Supply

Fig. 12 Glow Plug Relay Socket:

*** UPDATED BY TSB #288609 NOV 1986

1. Disconnect the wire from the engine coolant temperature sensor.
2. Connect a test lamp to a good ground on the engine, connect the other end of the test lamp to an accessible glow plug, and turn the ignition key to the run position for about fifteen seconds. The test light should glow, and on non-turbo vehicles should remaining on for a few seconds after the dash indicator lamp goes out. If the test lamp illuminates, proceed to step 4. If the test lamp did not illuminate, proceed to step 3.
3. Check wiring from the glow plugs to terminal 87 of the glow plug relay holder, Fig. 12. Be sure to check the inline fuse that is located on the firewall. If a fault is found in this circuit, repair it and repeat step 2. If no fault is found, proceed to step 5.
4. If the vehicle passed test step 2, but the vehicle still has trouble starting when cold, remove the bussbar and check each glow plug. Using either a test lamp or an ohmmeter, check for continuity through each glow plug. Replace any glow plugs that do not show continuity.
If any glow plugs are replaced, torque the new glow plugs to 22 ft. lbs. (30 Nm). This torque must not be exceeded because increasing the torque beyond the specification will cause closing of the ring gap, which can lead to premature failure of the glow plug.
5. Disconnect the glow plug relay from its holder. Using a volt meter, check for battery voltage at at terminal 30, Fig. 12. Battery voltage should be present at this terminal at all times. If voltage is not present at this terminal, check the wiring leading to terminal H of the fuse panel relay plate (non U.S. built vehicles), or the wiring leading to terminal 30 of the starter solenoid (U.S. built vehicles).
6. If there is voltage available at terminal 30, check for voltage at terminal 86 of the glow plug relay holder plate. Voltage should be available with the ignition switch in the run position only. If voltage is not present, either the fuse box relay plate or the ignition switch is faulty.
7. If voltage is available at terminal 86, test for voltage at terminal 85 by testing between terminal 85 and terminal 30. If voltage is not available, check the circuit from terminal 85 and ground.
8. With the ignition switch in the start position, check for voltage between terminal 50 and terminal 85. If the test lamp does not illuminate, check the circuit between terminal 50 and the ignition switch.
9. If the vehicle passes tests 5 through 8, but the glow plugs still do not receive voltage, replace the glow plug relay.