General Description
The glow plug system is composed of a 50 A glow plug fuse; glow plug
relay; head temperature sensor and 4 Bosch quick glow plugs.
The function of the relay is to turn on electricity to the plugs
until they (or the head) is warm enough to start the engine when
cranking. Access to all these parts is easy except for to the
glow plugs and bus bar connecting them. Two of the glow plugs
are behind the injection pump, and the other two are on either side
of the head coolant connection.
The relay turns on power when turning the ignition key to pre-glow, and turns off power when one of the following conditions are met:
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How to test if the glow plugs work
The mechanic's approachWith the fuel injectors pulled:
The electrical engineer's approach
The home tinkerer's approachSeveral not-so-precise methods:
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Things that go wrong and how to fix themIndividual glow plugs brokenThis is often caused by a "dripping" injector (an injector which does not completely shut off below the threshold pressure), drastically wrong injector spray pattern (dirty/worn nozzles) or some other injection system malfunction. Not much to do other than replace the broken glow plugs (and fix the injectors).If you need to remove the glow plugs behind the injection pump, or the electric bus bar, it helps to first remove the injector lines. Glow plug electrical control system acting up
Common problems here are:
If the problem is related to the temperature shutoff, you can just pull (and leave unconnected) the cable to the temperature sensor on the head. More precisely the temperature sensor is on the fitting which connects the radiator return and the thermostat bypass hoses. See the picture to the right for a detailed view. For a general view see the overview picture first in this document. This will inhibit the temperature shutoff. Instead of waiting for dash board pre glow light to go out just count 10 seconds (or 15-20 if it is cold), and start the engine. Some more advice by Jake Russell Also as Harvey Chao has found out, the Relay can malfunction in a way so the dash LED goes out but the power to the glow plugs remain on (during driving). Read about his extra glow plug light |