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  #1  
Old 06-03-2010, 04:47 PM
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Glow plug fuse keep blowing

Having a problem with my 1985 300D Turbo. The glow plug fuse kept blowing so my mechacic said it was the glow plug control box. I replaced the glow plug control box, but it still keeps blowing. Thought it might be the glow plug wiring harness but can't find one to replace it with anywhere. Before I build one does anyone have any ideas.

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1985 300D Turbodiesel 270,000 (Greasecar)
1999 Chevy Suburban 280,000 (Long hauler)
2011 Toyota Camary (Wife Car)
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  #2  
Old 06-03-2010, 04:58 PM
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It almost has to be a harness problem, the plugs normally do not fail grounded, they fail open. The plug resistance is low, around 1.2 ohms, so you need a reasonably good meter and good connections to be able to tell the difference between a good plug and a grounded harness. Did you take off the larger plug and measure resistance between each terminal and ground; each should measure around 1.2 ohms. Another check would be to disconnect the wire from each plug and repeat the above, any terminal that shows other than open has a grounded wire. The relay can be checked by disconnecting the plug and doing a glow cycle, if the fuse blows, it's not the harness.
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  #3  
Old 06-03-2010, 05:06 PM
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Guess your right but will test it to be sure. Anyone know where I can buy a harness?
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1985 300D Turbodiesel 270,000 (Greasecar)
1999 Chevy Suburban 280,000 (Long hauler)
2011 Toyota Camary (Wife Car)
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  #4  
Old 06-03-2010, 10:07 PM
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any junkyard should have one.
however, only way the harness could be blowing fuse is if a wire is shorted to ground. if you pull the harness away from all engine surfaces it will eliminate any grounds.
a visual inspection should spot any wires touching ground.
if all the wires were shorted together it would not blow the fuse. electrically all the wires go the same place, so it should not matter.
follow the harness with your fingers and see if any wires are touching the block/injector lines.
my bet is you changed glow plugs recently, and one of the wires is touching the block near the glowplug.
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  #5  
Old 06-04-2010, 01:01 AM
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I can remember reading at leat 2 times where the cause of a short was that the little Nut on the Glow Plug and come off and the Glow Plug Wire for that Plug follow and was simply touching and grounding itself to the Block.

If you did the test with the Ohm Meter and located which wire it was you would most likely only have to change 1 wire.

Also If you removed the original Wiring harness and inspected it there is a good chance it the insulation could be repaired.
They have stuff generically called Liquid Electrical Tape that you paint on.

I would look for the short to be down under the Spin-On Filter where there is a Metal Clamp that the Wires go through.
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  #6  
Old 06-04-2010, 11:34 AM
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Thanks

Thanks all, now my weekend has a purpose.

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1999 Chevy Suburban 280,000 (Long hauler)
2011 Toyota Camary (Wife Car)
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