Glow Plug Timer

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Oct 13, 2010
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Hi Guys,

Thought I would do a write-up on my jay car timer install.

When I bought my D21 the glow plugs were heated by a push button on the dash...this was the same for my previous car-an old patrol.

Instead of playing with the stock system (that was hooked up, just not working) I went for a manual option. I purchased a manual timer, led, push button switch and some wire from Jaycar - for around $50 or so.


While playing around with the wiring, I found the d21 had a high idle setup, that was disconnected completely.
This unit is a air switch, that used vacuum to activate a actuator mounted to the fuel pump. The actuator would then pull the accelerator slightly, giving it a higher idle.

I decided to incorporate this directly into the glow plug relay, so the car would have high idle while warming up.


Here is the wiring diagram I made for the install


I decided to run the LED directly from the Nissan relay..this means that it will only come on when the system is getting power. Wired in this way I would be able to tell if the standard Nissan relay is working...

The timer unit is relatively simple. You feed it power, feed it a relay input and when you activate the timer it will engage for a preset time that is setup with a switch at the end. You can also setup a off switch to manually turn it off, however since I connected it to IGN I figured if I needed to manually turn it off ill just use the key.

This means the unit will turn off when the car is starting.

So the theory behind it is:
Key to IGN - push button - count to 5 - start - push button again.

As the relay is set to around ~30 seconds, this works about to be long enough to warm the car up completely (EGT wise, coolant is still cold).

Normally when starting the EGT will average out around 88deg if you just let it idle up from cold....but this takes a while without plug assistance....with this new starting procedure it will warm the car up to around 90 on the EGT...

anyway here is some pictures and a video.






That's it.

Let me know if you have any questions or comments,