Electrical 86 Jeep CJ7 Loses all electrical power when driving

[Bobby T]

86‘ CJ7, 4.2L Automatic. I’ve had multiple electrical issues since I purchased this jeep several years ago. Recently I replace the battery, cables, and starter, solenoid. As I was driving home yesterday all electrical shut off. I stopped put the jeep in park, turned the ignition off then it restarted back up. It did it again, I did the same thing and it restarted and I drove home. I just checked all battery and solenoid connects, all good. Now headlights will come on but none of the electronic come on when I turn the ignition key, nor will it turn the engine over. I tried shifting in and out of park, and even tilting the steering wheel, still nothing lights up when I turn the key…any thoughts on what to check?

 

[TSB8C]

Number of possibilities. The ignition switch itself could be bad. Not the lock cylinder in the column where you turn the key, but the switch itself mounted on top of the column near the base. Could also be the main power connection at the bulkhead connector on the firewall. There is a single pin in that connector with a large red wire on it that feeds power from the battery into the fuse box under the dash. It is the second row down second pin from the left in this pic "labeled "Main Power Feed":



Over the years, the insulating grease used on these connectors gums up and can cause a bad connection between the bulkhead side and the connector that plugs onto it. I like to remove the pins, clean them with a wire brush, then use fresh dielectric grease when replacing them.

 

[Armyvet25]

Yeah, check the main power connection at the bulkhead connector on the firewall but betting on the ignition switch mounted under the dash on the steering column.

 

[Bobby T]

Number of possibilities. The ignition switch itself could be bad. Not the lock cylinder in the column where you turn the key, but the switch itself mounted on top of the column near the base. Could also be the main power connection at the bulkhead connector on the firewall. There is a single pin in that connector with a large red wire on it that feeds power from the battery into the fuse box under the dash. It is the second row down second pin from the left in this pic "labeled "Main Power Feed":

View attachment 77810

Over the years, the insulating grease used on these connectors gums up and can cause a bad connection between the bulkhead side and the connector that plugs onto it. I like to remove the pins, clean them with a wire brush, then use fresh dielectric grease when replacing them.

Thank you for the information. I’ve tackled a lot of projects on this Jeep, and overall it’s in good shape, but the previous owner created a “birds nest” in the wiring under the dash and hood. There are no “add on” accessories on the Jeep but there are wires running everywhere, some connected and some not. Also, I’m having issues with some of the gauges working, which could be a grounding issue. At what point do you pull all the wiring out and start over? I’ve read through the Painless Performance Wiring Harness installation info, and curious if anyone has had any experience doing this. It didn’t look that complicated.

 

[Armyvet25]

This may help your journey through the Electrical wiring fun along with other items
CJ 84-86 service manual with Electrical
once there, follow below to download pdf



if you get any browser warnings, it's safe, it's my jumpshare file host

 

[Bobby T]

This may help your journey through the Electrical wiring fun along with other items
CJ 84-86 service manual with Electrical
once there, follow below to download pdf
View attachment 77813
View attachment 77814

if you get any browser warnings, it's safe, it's my jumpshare file host

Thank You!

 

[Armyvet25]

No problem

 

[TSB8C]

At what point do you pull all the wiring out and start over? I’ve read through the Painless Performance Wiring Harness installation info, and curious if anyone has had any experience doing this. It didn’t look that complicated.

When you're first working on it. My last three CJs I just pulled the three harnesses (engine bay, under dash, going to rear) and I unwrap them on my dining room table. Solder all the splices, clean what needs it, and then add whatever I'm adding on (trailer light plug, fuel injection, alarm, secondary battery, remote start, spot lights, onboard air, custom sound, etc). I also add ground connections rather than just relying on grounds via body/dash mounting points (like the gauges, lights, etc). I've never used an after-market wiring harness like Painless or others. I hear good things about the Painless setup. But in my case, if I have all the connectors and wiring in place already on the stock harnesses, I just revamp it as explained. Now if someone has cut off connectors or wires or parts have been burned, corroded, rusted too bad, then you would need a replacement for sure.

 

[Bobby T]

When you're first working on it. My last three CJs I just pulled the three harnesses (engine bay, under dash, going to rear) and I unwrap them on my dining room table. Solder all the splices, clean what needs it, and then add whatever I'm adding on (trailer light plug, fuel injection, alarm, secondary battery, remote start, spot lights, onboard air, custom sound, etc). I also add ground connections rather than just relying on grounds via body/dash mounting points (like the gauges, lights, etc). I've never used an after-market wiring harness like Painless or others. I hear good things about the Painless setup. But in my case, if I have all the connectors and wiring in place already on the stock harnesses, I just revamp it as explained. Now if someone has cut off connectors or wires or parts have been burned, corroded, rusted too bad, then you would need a replacement for sure.

Thank you for your suggestion. A lot of the wires have been spliced multiple times using different color wires. I traced one wire this evening and it changed colors four times. I may start by pulling the harnesses and seeing if they are salvageable before purchasing a new one. I’d like to hear if anyone has installed a Painless harness.

 

[Bobby T]

This may help your journey through the Electrical wiring fun along with other items
CJ 84-86 service manual with Electrical
once there, follow below to download pdf
View attachment 77813
View attachment 77814

if you get any browser warnings, it's safe, it's my jumpshare file host

Thank you!

 

[CJ]

Thank you for your suggestion. A lot of the wires have been spliced multiple times using different color wires. I traced one wire this evening and it changed colors four times. I may start by pulling the harnesses and seeing if they are salvageable before purchasing a new one. I’d like to hear if anyone has installed a Painless harness.

I've installed several of the Painless kits on various vehicles. They are well made and I didn't have any problems. Sounds like you have no problem with 12v wiring so you shouldn't have any problems if you decide to go that route. I would recommend you look at a PowerProbe if you want to make your electrical troubleshooting easier.

 

[Bobby T]

I've installed several of the Painless kits on various vehicles. They are well made and I didn't have any problems. Sounds like you have no problem with 12v wiring so you shouldn't have any problems if you decide to go that route. I would recommend you look at a PowerProbe if you want to make your electrical troubleshooting easier.

I have a Fluke Multimeter and a test light. Is there a particular PowerProbe model you would recommend? What do you like about it? Thanks

 

[CJ]

I have a Fluke Multimeter and a test light. Is there a particular PowerProbe model you would recommend? What do you like about it? Thanks

Well, since you have a Fluke you defiantly know quality...
The latest version is the link-->> PP4 - I have the link-->> PP3. How much depends on what accessories you get.
The reason they are so good is you can backfeed +12v for testing. I also have the ECT3000 (included in some kits) for shorts and open circuits.

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[Bobby T]

Well, since you have a Fluke you defiantly know quality...
The latest version is the link-->> PP4 - I have the link-->> PP3. How much depends on what accessories you get.
The reason they are so good is you can backfeed +12v for testing. I also have the ECT3000 (included in some kits) for shorts and open circuits.

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Thank you, great advice on test equipment.

 

[j6824]

Number of possibilities. The ignition switch itself could be bad. Not the lock cylinder in the column where you turn the key, but the switch itself mounted on top of the column near the base. Could also be the main power connection at the bulkhead connector on the firewall. There is a single pin in that connector with a large red wire on it that feeds power from the battery into the fuse box under the dash. It is the second row down second pin from the left in this pic "labeled "Main Power Feed":

View attachment 77810

Over the years, the insulating grease used on these connectors gums up and can cause a bad connection between the bulkhead side and the connector that plugs onto it. I like to remove the pins, clean them with a wire brush, then use fresh dielectric grease when replacing them.

Can also use spray electrical contact cleaner...will dissolve the gum

 

[Armyvet25]

I’d like to hear if anyone has installed a Painless harness.

Nope, I get a big piece of plywood and make a wire board, I pull any wiring harness that is even remotely messed up, lay it out, mark everything, salvage connectors, pitch in the trash, and then build an entire harness from scratch adding things I want and removing others. I actually like wiring, I know I'm strange. But not recommended for the weak if not electrical savvy, a lot goes into this as far as determining optimum wire gauge, based on draw, length of wire, relays, added accessories, etc.

 

[CJ]

Nope, I get a big piece of plywood and make a wire board, I pull any wiring harness that is even remotely messed up, lay it out, mark everything, salvage connectors, pitch in the trash, and then build an entire harness from scratch adding things I want and removing others. I actually like wiring, I know I'm strange. But not recommended for the weak if not electrical savvy, a lot goes into this as far as determining optimum wire gauge, based on draw, length of wire, relays, added accessories, etc.

I love wiring also, it's relaxing for me. I like making custom harnesses that only have what's needed.

I'm lucky enough to have a great surplus location near me that sells bulk wire. -->>Skycraft Surplus

 

[Bobby T]

I love wiring also, it's relaxing for me. I like making custom harnesses that only have what's needed.

I'm lucky enough to have a great surplus location near me that sells bulk wire. -->>Skycraft Surplus

I don’t think it’s strange, it’s like any hobby…if you enjoy it and it helps you to relax in a stressful world, then good for you.

 

[NP435]

86‘ CJ7, 4.2L Automatic. I’ve had multiple electrical issues since I purchased this jeep several years ago. Recently I replace the battery, cables, and starter, solenoid. As I was driving home yesterday all electrical shut off. I stopped put the jeep in park, turned the ignition off then it restarted back up. It did it again, I did the same thing and it restarted and I drove home. I just checked all battery and solenoid connects, all good. Now headlights will come on but none of the electronic come on when I turn the ignition key, nor will it turn the engine over. I tried shifting in and out of park, and even tilting the steering wheel, still nothing lights up when I turn the key…any thoughts on what to check?

I had this in my CJ7 so a switch on the dash to battery, out to the DUI ignition, fresh wire properly waterproofed and zero trouble after. Cost me 60 bucks for supplies and beer after.

 

[Bobby T]

I had this in my CJ7 so a switch on the dash to battery, out to the DUI ignition, fresh wire properly waterproofed and zero trouble after. Cost me 60 bucks for supplies and beer after.

I found that the wiring harness running above the steering column has a short in the plug. I can wiggle the plug and the dash lights turn on and off. I’m going to try some contact cleaner and see if that helps.