Need help with glow plug system

[99' 444]

My uncle has a 94' turbo diesel that has recently gotten hard to start. I just tried to check the glow plug relay with a volt meter, and when my uncle turned the key on some wires started smoking from under the air intake. He said he had a fire under there before. Does anyone know what's going on there. I think I've read on here before that if something goes bad on the glow plug sysetem (maybe the controller?) that it could start a fire. Can anyone shed some light on this? We could also use some help with diagnosing the whole glow plug system. I am not familiar with the IDI system. Thanks for your help.

 

[smolkin]

Here's a schematic for system:

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You may have a wire(s) grounding out where the insulation has cracked...these wires can get hot.

 

[rhkcommander]

I've seen old relays smoke before, in that schematic it would be located left of the SOLID STATE GPC label.

Also, a lot of the wiring can be worn and shorting out, there is usually oil, dirt, leaf debris, and other stuff that could do the trick. Every single glowplug wire has a fusible link as far as i recall from when i tore one apart. I have seen the yellow and/or brown wires come undone and short out against the valley pan or valve covers/etc. Usually one not both, if both yellow gave up you wouldn't get any glowplugs at all. Plus when only one wire is doing the work, the other gets hotter carrying the load... I want to say in this guys case he had a yellow wire break loose from the end of the connector, lucky for him it was caught before it could do real harm.

Pic I pulled off the internet
http://international4700parts.com/products/photos/4_4.jpg

 

[ghunt]

I had a glow plug short and catch fire on my old truck...that was fun. I had to cut some of the wire off and splice a new piece in, and there's not a lot in there to work with as it is.

 

[icanfixall]

Generally pseaking the two wires in the engine main wire harness that feeds the controller melts the plug where the harness seperates from the frame wire harness. Look at the top of the engine for the large bundle of wires feeding all the electrical on the engine like the senders and things. The plug is about 3 inches long and 1 inch wide. At one end of that will be the controller wires. On my truck they were yellow but not known colors on your rig. They are a double wire with a single connectioin lub ob each end of it. One end attaches to the fender mounted solenoid and that side of the solenoid is powered up hot all the time. Just trace the hot wire back to the positive battery terminal so see this. Anyway if that plug has melted its a reason to run a large gauge 6 wire from the solenoid to the controller. I simply went to a audio speaker shop and bought some multi strand wire in 6 gauge and the lugs to fit that. No reason to remove all the old wire from the engine harness. Just cut it off cleanly and forget about it.. Out of site.. Out of mind. If you really want to get fancy add a fuse in that line. I choose not to because I never plan to remove my engine again. If something causes me to remove it I will lift the new 6 gauge wire from the controller and thats done.

 

[crewchief219]

I had the same problem, it was exactly what icanfixall explained. I ran a 4 gauge battery cable from a starter relay post to my power on the controller. I put a 250 amp fuse too. Its been working like a champ. Like icanfixall was explaining, look for the harness under your airbox, should be pretty close to the power steering pump. Thats more than likely the culprit. The two yellow wires are the power wires for the controller.