The Diesel Stop banner

1 - 18 of 18 Posts

·
Registered
Joined
·
212 Posts
Discussion Starter #1
Turned the key in the truck yesterday and noticed smoke rolling out from the right edge of the hood. After some exploring and removing the battery, I found a smoldering wire. I've attached a picture of the wire in question. It comes of the relay mounted to the right fender just behind the battery. I've read that there are two fusible links that run from the relay to the glow plug system, but everything I've seen says the wires should be yellow. This starts as black/orange-stripe then goes green then connects to black/yellow-stripe wire.



My questions (so far):
Are these the wires that lead to the glow plug relay?
Is the green burnt section the actual fusible link or is that in the black shrink tube area that is labeled as fuse link?
Am I safe to just replace this with two new fusible links, or will it almost certainly burn out again? (Representing a more serious issue)
 

·
Registered
Joined
·
212 Posts
Discussion Starter #2
So they are definitely not the wires that go to the glow plug controller, I traced those out and these aren't it. These come off the relay behind the battery then go around the front of the truck by the radiator and over near the brake booster. I believe they connect into that massive plug that connects all the wires from the engine bay to the interior. Couldn't find them listed on my wiring diagrams.

My tester didn't show continuity through the wires to ground, but I have a feeling if it were only grounding out a bit it might show it.

To answer my other question I believe the green wire in my picture does compose the actual fusible link, and the black labeled section is really just a butt-splice with heat-shrink tubing over it.

Not sure what's left to do besides just replacing the fusible links and hoping it doesn't burn up again.
 

·
Registered
Joined
·
2,303 Posts
According to my '88 FSM there are 2 fusible links at the starter relay - one going to the alternator, and one going to the trailer lights relay at the rear of the driver's side fender.
 

·
Registered
Joined
·
212 Posts
Discussion Starter #4
I don't think those are the two I'm having problems with. These are 10GA wire with 14GA fusible links. I see the one going to the alternator and it's much smaller. Does your FSM list a black/orange stripe wire coming off the relay that splits into two 14GA fusible links then becomes 2 black/yellow-stripe 10GA wires?
 

·
Registered
Joined
·
73 Posts
I don't think those are the two I'm having problems with. These are 10GA wire with 14GA fusible links. I see the one going to the alternator and it's much smaller. Does your FSM list a black/orange stripe wire coming off the relay that splits into two 14GA fusible links then becomes 2 black/yellow-stripe 10GA wires?
DR: My 1988 Electrical and Vacuum Troubleshooting Manual shows 8 fusible links at the starter relay on the right fender apron. One end of each link is attached to the starter relay hot terminal and the other is attached to the wire whose color I indicate below.

3 are green 14 AWG links. 4 are black 16 AWG links. The last one is a blue 20 AWG link. This connects to the wire (yellow) to fuse #1 (stop/hazard/speed control).

The 3 biggest green links attach 1 to the alternator wiring (black/orange to regulator and yellow/white to alternator) and 2 to black/orange stripe Glow Plug Controller wires (that later become yellow after a connector).


The 4 black links are for ignition switch (yellow), trailer brake control (red), trailer lamps (yellow), headlamp switch and horn fuse #16 (black/orange).

So there are 3 black wires with orange stripe - 2 should be connected to green 14 AWG fusible links and 1 connected to a black 16 AWG fusible link.

Good Luck.

Regards,
 

·
Registered
Joined
·
212 Posts
Discussion Starter #6
Ok, I'm dumb. They were the wires that went to the GPC. The fact that they went all the way forward then pulled a U-turn was too much for my brain to process. The wires were also burnt in the fender plug where the wires go from black to yellow.

I bypassed all that by running two of my own 10GA wires and using two 14GA fusible links. The GPC worked and there was no smoke when I turned the key on. However, the fusible links get really really hot, almost too hot to touch. I realized that they are designed to blow when they get too much load, but for normal usage should they get that hot?
 

·
Registered
Joined
·
73 Posts
DR: A common problem in that connector is for corrosion/poor contact to cause resistance heating that destroys the connector (by melting it). My 2 10 AWG wires and fuse links were replaced with a single 6 AWG wire in split loom with a 150A fuse.

Regards,
 

·
Registered
Joined
·
212 Posts
Discussion Starter #8
Yeah, the two 10GA wire terminals were all melted. The rest still looked intact.

This morning I went out and cleaned both connection points and the GP side of the GP relay. Fusible links were a little less hot but still definitely warm. I left the fusible links a little longer than the originals, not sure if that would make them warmer or colder (i.e. burn out quicker or stay in tact longer).

It's very hard to find good information on fusible links online.
 

·
Registered
Joined
·
1 Posts
FUSIBLE LINK REPAIR

quote However, the fusible links get really really hot, almost too hot to touch guote

Does replacing the fusible link with better copper wire increase GP voltage above spec and hasten burnout? If no, seems like a very good idea.
 

·
Registered
Joined
·
11,824 Posts
Charlie Davis, this thread is 8 years old, but Jim X 3 is correct. This was a VERY common problem when these trucks were new. The fusible link did not overheat and burn out, what overheated and burned out was the connector next to it as Jim posted above.
 

·
Registered
Joined
·
51 Posts
Thanks for your response. 395K and going strong. New paint, BTS trans/chip, 2,500 dollars of dynamat..........quieter than new according to DB meter (obviously more engine noise). 17.6-18.2 MPG at 70-75 MPH (hand calculated). 57 gal transfer flow tank allows easy 800 miles days with no refueling. Oil samples by blackstone.......all good. Clean air (Severe Duty Ford filter), clean oil, Ford (every 3.5-4K miles), and clean fuel by Racor with Power Master additive every fill up. Virtually no oil consumption.

Issue: Changed two Ford reman alternators for preventive maintenance at around 160K each. Third reman never saw above 13.8 volts minimum acc load 85-100 degrees outside temp. Steady state 13.2-13.5 depending on load. Put on a fourth. Same. Why I went with after market. QuickStart 160A. Range is 13.6-14.4 never dips with increased load (like turning fan to high). Normally try to stay with Ford parts. Odessey batteries. Talked to their engineer. Said I needed a bigger alt. Lots of glow plug potential damage threads. Talked to BERU engineer. Said no issue as long as I keep up with maintenance. I still am running original glow plugs and injectors. No issues last winter starting down to 12 degrees.
S/F
Charlie
 

·
Registered
Joined
·
1,616 Posts
For 2,500 dollars of dynomat, that sucker better be quieter than a sound room.

Sent from my SM-G892A using Tapatalk
 

·
Registered
Joined
·
11,824 Posts
I still am running original glow plugs and injectors. No issues last winter starting down to 12 degrees.
Yessir, my glow plugs were all working just fine when I changed them last time at 80,000 miles and 11 years on them. And then the phony info floats all around the net from anyone BUT a diesel mechanic that injectors and IP's only last 100,000 miles. And then of course you can't change one without the other or you'll destroy it. :)
 

·
Registered
Joined
·
1,574 Posts
Yessir, my glow plugs were all working just fine when I changed them last time at 80,000 miles and 11 years on them. And then the phony info floats all around the net from anyone BUT a diesel mechanic that injectors and IP's only last 100,000 miles. And then of course you can't change one without the other or you'll destroy it. :)
That is all very true. I am usig a IP that is from 3 egies ago. HUMMM looks like a letter o my keyboard quit
 

·
Registered
Joined
·
52 Posts
Ha! I've had that happen!

That is all very true. I am usig a IP that is from 3 egies ago. HUMMM looks like a letter o my keyboard quit
Yes, this has happened to me, too-and it was the "n" that went bad on one of my laptops as well!
 

·
Registered
Joined
·
1,574 Posts
Yes, this has happened to me, too-and it was the "n" that went bad on one of my laptops as well!
I have found out that copy and paste works pretty well until I find a new keyboard, or 'puter. Sometmes it comes out wrogn though.
 
1 - 18 of 18 Posts
Top