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Glow plug electrial issues

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Old Nov 17, 2007 | 07:02 PM
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Glow plug electrial issues

Something is supplying too much voltage to my plugs. I keep burning up the fusible links on the blk/org wires that lead to the controller. Both are listed hot all times on my schematic. There is also a fusible link along the front of the passenger side fender well that has cooked. Here is the weird part, if I have less than 8 plugs connected it seems to work. Anytime all 8 are connected it will cook the links and throw more than 60 amps through the one near the fender. So I can disconnect 1 glow plug and the system works even with the link at the fender disconnected. Not sure what that is for as it is not on my schematic from the powers at Chilton. All the plugs tested ok last month. Going to recheck them asap. Am I correct in that voltage goes to the controller, but not from it? Any ideas what could be causing this condition? Thanks.
 

Last edited by baddarryl; Nov 17, 2007 at 07:04 PM.
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Old Nov 17, 2007 | 07:41 PM
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You are correct, battery voltage to the controller relay at all times.
A glow plug system working propperly uses about 200 amps when the glow plugs are heating.

12 volts into .5 ohms resistance equals 24 amps per glow plug.
8 glow plugs makes for 192 amps draw.

Something tells me you have either a glow plug that has shorted internally or you have a short in your glow plug harness.
 
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Old Nov 17, 2007 | 08:40 PM
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Baddaryl look at manual glow plugs thread real close to yours Dave has pictures of the relays and how the are wired simpler than the manual.
what brand gps are you using.
 
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Old Nov 17, 2007 | 08:55 PM
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Motorcraft, about a year old.
 
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Old Nov 17, 2007 | 09:44 PM
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What color are the wires on both sides of the link that keeps blowing that is not in your book?

Are you working on the 91 in your sig?
 
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Old Nov 18, 2007 | 11:47 PM
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Yes 91. Upon closer inspection it looks like one of those blk/org wires coming out of the harness is what is leading into that fuseible link which goes to hot on the starter solenoid. The other blk/org wire loops around and also looks like it ends up hot also with its own built in fusible link, but that one hasn't burned. It is on the schematic as the blk/org, I just couldn't tell they way they are harnessed. Somethings making both of them burn up just before they connect to yellow that heads to the controller.
 
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Old Nov 19, 2007 | 08:39 AM
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OK with my analog meter set on Rx100 I read .6 at almost every plug.
 

Last edited by baddarryl; Nov 19, 2007 at 08:59 AM.
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Old Nov 19, 2007 | 09:19 AM
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Originally Posted by baddarryl
Yes 91. Upon closer inspection it looks like one of those blk/org wires coming out of the harness is what is leading into that fuseible link which goes to hot on the starter solenoid. The other blk/org wire loops around and also looks like it ends up hot also with its own built in fusible link, but that one hasn't burned. It is on the schematic as the blk/org, I just couldn't tell they way they are harnessed. Somethings making both of them burn up just before they connect to yellow that heads to the controller.
Update:
I found your pic of glow3.jpg, but I cant upload it for some reason. The ones I am having trouble with are the 20g links at the Engine Connector which loops through the wait to start lamp (which works) and back to the Connector (same as relay?) The other that has melted is the 14ga fuse link that loops at the battery (as described to starter solenoid above).
 
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