Hilux 2.4l diesel constant 10v to glow plugs problem (1 Viewer)

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Nov 8, 2017
Hi every one. New to the forum but not to these diesel truck world. I have this issue which I am struggling with for the last couple of weeks. So a few weeks ago I suddenly lost all glow plugs, one morning it was ok and the other nada, went threw the testing procedures both in the haynes manual and the toyota manual for 2lt and 3l engines. Relays ,resistor , water temp sensor all seem to be good, couldnt really test the glow plug timer since I cant find the correct connector diagram , the ones in the manuals are different than mine(see photos) so couldnt tell if the timer is faulty or the wiring. The problem: for the first few seconds when the switch is on I get 12V at the glow plugs strap, then I it clicks and turns to 10V wich wont go off at all even when the engine is fully warmed up or at all, guess this is what burnt my glow plugs. The weird thing is I get this 10v even with both relays disconnected. A new timer is expensive but this is the way id like to go but I want to be sure its the timer that is faulty and not something else I might be missing. Am I missing something? What else can I check?Any advice or comments very much apriciated..



I had a similar problem a couple of weeks ago- all my glow plugs burned out at once. I tested the glow system and it was working fine except for the burned out plugs...

So my theory is that one of the glow relays stuck on, burned out my plugs, and then released by itself after it killed the plugs.
I've installed a voltmeter and a buzzer to my glow busbar so I will know if the relay ever sticks again and I can stop the truck and give the relay a whack to stop it from sticking.

Thought 1: if you have power to your busbar all the time, I would think that perhaps one of your glow relays may be stuck on as well. Try disconnecting the relay and test for electrical continuity through the switched part of the relay.

Thought 2: I did see in your post above that you tested the relays, but I'm not sure I understand how there is still power going through them, even when disconnected... Is the truck new to you? Is it possible that the glow system has a Wilson switch engaged and overriding the system somewhere?
Freewheel, thanks for your help! I Have this truck for arond 5 years now. It is weird to me that power is going to the busbar even when they are both disconnected . The power will stop only if I disconect the glow plug timer (or obviously the fuse).
So still not sure...
We have an old electronics tinkerer here in the valley and he'll atemp just about anything. I would bring your relays into a professional.
I know you said you want to fix the stock timer, but fwiw I spent 3 days trying to fix mine with the help of my electrical engineer best friend. I finally gave up and built a Wilson switch
setup in under an hour. Works great.

+1 for setting up an led/buzzer indicator on any system (Stock or wilson)

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