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Glow plug timer controller troubleshooting.

100 Views 0 Replies 1 Participant Last post by  BW22
Hey working through the list of issues on my used patrol. Trying to troubleshoot the glow plug system, I didn’t see a specific post on this, if it’s there feel free to direct me to it, thanks.
My glow plug light stays on almost continuously. After about 45 min of driving sometimes it turns off. I’m suspecting the timer but want to check with the pros before I dump money into it.
-when I disconnect the wire to the glow plugs there is always voltage (key off and out) from the battery to the wire. From another thread and the wiring diagram I think this is normal as the system switches ground. There is not voltage measured on top of the glow plug when off.
- I hear the solenoid by the RH side on the firewall clicking off once the key is in On position. It’s on for about 18 seconds when the engine is cold.
-Voltage measured from the top screw on the front glow plug to engine ground is 10.4 while the gp’s are on then zero once the relay clicks off.
  • voltage once the engine is running is 4.5 -8 volts. It’s probably steadier but depends on how well I’m holding the probes.
  • after about 7 min the voltage is zero at the glow plugs.
  • the car starts fine. No white smoke
  • I pulled the plug to the two terminal temp sensor on by the upper radiator hose. (Is this the right sensor?) .59 ohms after the engine had cooled for about 30 min changing to .43 ohms once the engine started and warmed up.
  • I pulled the connector to the timer/ controller the terminals looked ok. the dumb dash light did go out and the glow plugs didn’t come on…
-I am also suspecting a weak battery, sometimes the batt is slow to pull the engine through the first compression stroke. Once I’m past that it starts fine. 12.48 volts cold 14.0 volts running. 11.5 with plugs on and 9.5 whole cranking.
I’m thinking the glow plug system basically functioning. The glow plugs are staying on longer than they are supposed to. Also the dash light is annoying but is not really reflecting what’s happening.

Anything else I should check?
Does this seem right?
I’m planning on getting a controller timer.


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