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Discussion Starter · #1 ·
Before my question i would just like to thank the guys on this site, always so helpfull and helped me get the gq going for another work week.

How many amps should the glow plugs fuse be?

the glow plug fuse located behind the battery. mine has a bit of wire jammed in there! now im sure its not ment to be like that, and no i didnt put it there. needless to say now i have no glow, i will be out with the multimeter very soon.

But for now im just manually glowing with some fencing wire :rolleyes:
 

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Discussion Starter · #3 ·
Ok thanks, whats a fusable link? is it those giant fuse jobbies?

I cant even find the wiring diagram of the TD42 in my book!
 

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Discussion Starter · #5 ·
Ok can somone help me understand exactly whats going on here.

1 Glow plug is screwed into motor which is earthed.

2 Tops of glow plugs are all joined together by the rail/bridge thingy.

3 glow relay sends 12v to the tops of the plugs making them glow like a big light bulb?

I have a short in the system somwhere that is making that "fusable link" get hot and smoke!:headwall:
 

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Discussion Starter · #6 ·
glow plugs are drawing about 18a anyone know if that sounds right?
 

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Sounds about right, 18a would mean roughly 8 ohms each. I can't recall the specs for the patrol plugs, but would have guessed around 4-6 ohms.
Was that with a cold engine? The resistance increases as the plugs warm up, so current decreases.
 

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Learned the hard way - RD28t out TD42 in
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Glow plugs will suck a lot more current than 18A - I suspect your measuring technique is at fault (current measuring is never easy). Measure the volts on the glow rail, when the motor is cold it should be around the 10 - 12V mark if the battery etc can cope. Then measure the resistance of each plug (with the rail off), they should all be the same - can't remember actual resistance but I'd expect less than 1 Ohm each). The smoke you refer to could just be oil from your sticky fingers on the fusible link burning off ? Or - as you seem to think - you could have a more serious problem (eg resistive connections in the fusible link holder ?) Make sure that there is no current draw when the plugs are disconnected, then maybe a new set of plugs. What motor are we talking about anyhow - if its a earlier RD28, then its more complex.
 

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To test your plugs you can take them off the engine (careful not to break the tip). Take a alligator clip to the top part of the plug connected to a 12v battery and touch the side of the plug to the negative post of the battery. If they work the tip will glow red hot in a couple seconds.

All plugs are joined together by a rail. The electrical connection to that rail may be in bad shape, rusted... Check it out. You can also cut that connection off, ditch the rail and bring individual wires to each plugs instead of using the rail. Use proper wire gauge.

The other components that could be faulty are solenoid before the rail or the ECU. ( not sure if it applies to the Patrol?). If there's a solenoid you can easily check it by disconnecting both wires and touching them for 3 sec then try starting your cold truck. If it starts easy it's probably it.

ECU can't help you but hopefully the rest can help you figure it out.

Cheers
Mr. D
 

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Discussion Starter · #11 ·
Thanks for all the help.

It was the relay causing the problem in the first place, it had a broken/melted connection inside it.

As for the once off smoke who knows:wink:

I am reasonably sure i had the amps measurement correct, but the engine was warmish by that stage.
 
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