The 1982 and later diesels (except Turbo models) have a new "quick-glow" system. Nominal glow time is seven seconds. Although the wiring for this system is the same as the earlier system, the glow plugs and relay cannot be paired or interchanged with earlier parts or vice versa, except on 1978 Dashers. On these Dasher models, you can convert from the old type system to the new type by simply exchanging the old style plugs and relay with the new type.
Quick-glow system plugs are identified by a brass nut on the plug wire terminals and by red lettering on the glow plug relay. Normal-glow system plugs are identified by an aluminum nut and white lettering.
- Connect a test light between the No. 4 cylinder glow plug and a suitable engine ground. The glow plugs are connected by a flat, coated busbar (located near the bottom of the cylinder head).
- Unplug the wire from the engine temperature sensor.
- Turn the ignition key to the heating position for no more than 15 seconds. The test light should light.
- There should be voltage to the glow plug for approximately five seconds after the glow plug indicator lamp goes out. Voltage is applied as a normal part of the controlled pre-heat period. If not, possible problems include the glow plug relay, ignition switch, glow plug fuse or a break in the wire to the relay terminal.
- If the test lamp lights, perform the individual glow plug checks as described below.
- Remove the wire and busbar from the glow plugs.
- Connect a test light to the battery positive terminal.
- Touch the test light probe to each glow plug in turn.
- If the test lamp lights, the plug is good. If the test light does not light, replace the plug.
A common cause of glow plug failure is worn glow plug tips. This is due to faulty injector operation in the related cylinder. This type of condition has nothing to do with the operation of the glow plugs. If you find that you are constantly replacing glow plugs, and have eliminated all possible electrical faults, check the fuel injector(s) for damage or have the injectors pressure and leak tested by a diesel injector repair shop.
REMOVAL & INSTALLATION
- Disconnect the negative battery cable.
- Loosen the nut and disconnect the wire from the glow plug terminal.
- Using the proper size deep socket, remove the plug from engine.
- Install the new plug, then tighten it to 29 ft. lbs. (40 Nm) on Quantum, Rabbit and Dasher models, or 22 ft. lbs. (30 Nm) on Golf and Jetta models.
- Connect the wire to the glow plug terminal, then tighten the nut until snug.
- Connect the battery cable.