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Electrical issues, 1986 Dodge PU

Hi, My Dodge 3/4T PU has always had electrical issues, some corrected, some we learned to live with or ignored if not critical to the operation or running.

Last week the truck completely died on my wife in rush hour traffic, and she said during the “Help!” call the truck had simply died, no lights on the dash or any response to the ignition switch. Lights and horn still worked. I arranged a tow home for her and truck.

While checking things out under the hood found the J1 wire, a fusible link had vaporized. The J1 comes off the rubber A1 distribution connection, and feeds the ignition switch direct from the battery.

I have done the research, and already ordered a new Maxi Fuse and holder to wire in as a replacement for the fusible link, but my question to the board is ‘simple’(hah!)…

Can anyone aim me in a direction to look for what caused the J1 to ‘fuse’? I assume a short, but…since J1 runs the engine electrical stuff thru the ignition switch, I’m baffled as to what might be shorted, if it is a short.

I’ve done electrical work to vehicles before, and realize the frustration and futility of dealing with intermittent or odd problems like this, so really just hoping for a leg up on things I can check, I’m not expecting a simple answer.

Still, older Dodges have the well-deserved reputation IMHO of having crappy electrical systems, and every Dodge I’ve owned has had some kind of problem or another, so maybe others have experience with the J1 problem.

The trouble may be intermittent and if so it may be rather hard to find. If the new fuse blows again then you may have a hard failure and it should be pretty easy to find that. Check for possible trouble areas like the exhaust system. A wire may have rested against it and burned the insulation. Also check for chaffed wires. If there is a trailer hitch plug check that also.

In order to kill a fusible link, you pretty much have to be looking at a dead short to ground somewhere. Without looking at a wiring diagram, I’m guessing this wire probably goes from the battery, into the fusible link, to the ignition switch, and then to the fuse panel bus that has fuses for everything that’s switched off when the key is off. If the problem was with some component that goes off with the key, a fuse in the panel would have blown. Your problem is most likely somewhere between the fusible link and fuse panel. Follow the wire and be sure the insulation hasn’t been damaged by rubbing against something. Pay special attention to where it goes through the firewall. Be sure no circuits have been spliced into this wire over the years, especially if these circuits are not fused. For that matter, be sure ALL circuits that were added are fused right where you tapped off power. Also be sure your fuse panel is securely mounted and not swinging under your dashboard. If everything looks ok and you haven’t found the problem, you might want to replace the burned out link temporarily with a 20 amp fuse. Next shake the heck out of everything and see if anything sparks or the fuse blows. When you figure it out, fix the problem and replace the burned out fusible link.

Thank you both for your advice and taking the time to respond. I haven’t had any time to really deal with this dead truck, but a friend and I did some preliminary testing. There is a definite dead short somewhere, we put a jumper between the A1 wire from the battery and the J1 wire that vaporized, there was no current passing thru, but the second the key was turned on, the wire started smoking. My friend, also an old shade tree wrench as I am, has suggested the ignition switch itself may be the cause. Does anyone have any thoughts on that?

I haven’t gotten any further with chasing wires, but I did strip off the outer tape wrappings from where the fusible link was back towards the bulkhead. The insulation on both the J1 and J10 red wires that feed the ignition show cracked insulation! I mean there are splits that go completely around the wire every 1/2 to 1". It’s like somebody started stripping the wire with the first insulation cut but didn’t remove the insulation–but in the whole length of the wires. This is a very scary thought, that the insulation Dodge used has failed. These wires are inside the factory loom, and were tape wrapped as well as inside the corrugated plastic conduit. It’s very discouraging to think that other wires could have the same failed insulation–no wonder the truck has been electrically haunted since the day we bought it.

Anyway, I was so discouraged to find the bad red insulation (only the red wire or red with a stripe show this defect) that I closed the hood and haven’t been back to resume the investigations. I think fuse box and bulkhead connector will get the scrutiny next. Thanx again for the help–the saga continues.

Jumpering the faulty circuit with a lead tied directly to power and with no fuse protection is not a good thing to do. This can only lead to more trouble by overheating the insulation on the wire. You may now need to replace the entire lead that ties to the fault. You would be wise in investing in a service manual for the truck. It will save you a lot of time and trouble in locating the problem.

Wire insulation going bad over time can be a real problem with some vehicles. You may have to replace the entire harness to really fix the trouble.

As far as locating the short I suggest you use an ohmmeter to check the wiring after the ignition switch. Disconnect suspected trouble areas at the connectors and watch for a change in the meter reading. You will most likely see zero ohms when the short is connected and possibly around 20 to 50 ohms when it is cleared. You can also use something like a brake light tied in series to power and to the shorted lead to safely find the fault as the light will limit the current to the short. The light will be bright until the short is diconnected. Once the short is removed the light will dim or go out.

Go to this website and become a member and post your question under “vehicle help”. There are very many mopar truck enthusiests, like myself that will be able to help you out a lot more than I could. Try using the search engine first, but sometimes it doesnt work to well.

Hi again. Cougar, we didn’t take any chances with the jumper, it was wire half the size of the fusible link, and my friend only held the wire touching while I turned the key. It was pretty quick when the key hit the run position, the smaller jumper showed it was a dead short–a fraction of a second and it was glowing and smoking–and disconnected.

I have now unwrapped the entire loom to the firewall connector and found no problems. There also were no blown fuses under the dash. However, I connected a VOM to the terminal on the firewall that connects the ignition switch to the blown fusible link. The battery is disconnected and the large bulkhead connector unplugged, but the meter shows about 200-225 ohms when the key is in the run position, and it climbs as high as it will go when the key is turned to crank.

Also, I noted simply wiggling the key in any position I could make the VOM needle move around. That led me to the remote ignition switch (with tilt wheel) and by just barely wiggling the actuator rod I can make the need move around. I’m thinking this could be a bad ignition switch.

I tried to remove it, but I can’t get the actuator rod out of the switch itself. I’ve read several repair guides for the switch and they all say I need to remove the steering wheel, ignition lock, blablabla just to change the switch down at the base of the steering column?

pgdvk1, I have joined the Ram group you suggested, and searched there with no joy, but I will post my question there–or maybe first I should post about removing the rod from the switch! One source said something about putting the switch in the ACC mode, but the rod was pretty well attached. I want the switch out to test and/or replace, and I can’t really see all the wiring that serves the switch under there with the switch in the way–can’t even see how to unplug the wire connectors.

Thanx again all, I’ll just keep plugging away chasing and testing wires unless the switch is the culprit. I spent over 40 hours once on a Chevette with a blown fusible link to find the short, and over 60 hours once on my BMW motorcycle to find a dead short that prevented running. I do know about electrical problems!