Fuseblock Tar

[Krispy]

My '87 MJ DD 2.5 has had an electrical gremlin. I recently replaced clutch slave, plate and pilot bearing. MJ ran great but a week later it would die for no reason while driving only to restart an hour later. Finally no power to most of fuseblock and ignition switch. In troubleshooting, I removed the windshield wiper tank and moved the wiring harness enough that relays clicked and I then had power to fuseblock. I put wiper tank back in place and again lost power to fuseblock. I was finally able to separate the fuseblock from the firewall only to find this thick black tar on all of the electrical connections. 5 years ago, I had the clutch master cylinder leak onto fuseblock which corroded the fuse connections which was solved by replacing all of the fuses. Could this tar have been dissolved from the brake fluid leakage and gradually seeped into the firewall connector keeping the fuseblock from making a good circuit? I now am trying to clean all of these connections of this tar to see if this is my gremlin. Suggestions? I am approaching 400k on this baby and need her running.

 

[64 Cheyenne]

http://comancheclub.com/topic/48463-cruisers-mostly-renix-tips/

 

 

#2 Although this is for a C101 connector, it is applicable to the engine firewall connector you are referring to.

 

And welcome to the club.

[cruiser54]

That's factory tar.

 

The connector you're messing with is the C100. Same applies to it as the C101 as suggested above. 

[Krispy]

I'm still having issues after cleaning C100 and C101 connections. I have no power at the steering column switch. The red 12 gauge wire at the C268 has no voltage, but does at the C100 male terminal.  Any suggestions?

[Krispy]

I found my gremlin. The 12 gauge red wire that feeds the ignition switch was corroded away on the engine side of the C100 connection under the dust shield. I cannot make a repair on this connection so I am re-routing this wire, bypassing the fuseblock. Now I am finding the ignition switch doesn't want to go back on the steering column. I am within 1" of meeting the mounting screws.  I am now trying to find the proper position of the "rod" down the steering column to the ignition switch. Also found the 12 gauge red wire on the headlight switch burnt and melted in the connector. I will make this repair and hopefully be gremlin free.

[gogmorgo]

You should look into upgrading your headlight harness. Many people (myself included) have found out about that burnt wire on the switch connector when it sets things on fire...

Basically the switch and wires just barely support the full load from the headlights, so as things age and corrode, eventually it overloads and overheats. The upgrade harness is a supplemental harness (you plug it into the existing one) and it uses relays to take the load off the switch. The existing wiring is used to trigger the relays, so all your lights and switches retain their functions. You can get them commercially for $30 or so, or you can make your own. Installation takes a half-hour.

Not only does it decrease the chances of your rig catching fire, you'll also notice an increase in headlight output.

[Krispy]

Thanks for the advice gogmorgo! It bothers me that the 12 gauge wires all seem to have issues. I have had headlight issues in the past few years and had to replace the switch twice in the past 5 years. Now that I have the instrument cluster out of the dashboard, I can see a need for a relay system on the headlights. Thanks!

[VixJeep]

I had just put a rebuilt engine in my 88 MJ Pioneer 4.0, and it developed a miss in the #5 cylinder. After $900+ at the dealer, and a new ECU, they said I needed a wiring harness. I bought a can of non conductive contact and electrical cleaner, an old toothbrush, a small pick, and a pocket flat head screwdriver and scraped and cleaned all of the connections. Problem resolved.

 

I'm right with you on the 400k miles.

[cruiser54]

I had just put a rebuilt engine in my 88 MJ Pioneer 4.0, and it developed a miss in the #5 cylinder. After $900+ at the dealer, and a new ECU, they said I needed a wiring harness. I bought a can of non conductive contact and electrical cleaner, an old toothbrush, a small pick, and a pocket flat head screwdriver and scraped and cleaned all of the connections. Problem resolved.

 

I'm right with you on the 400k miles.

NOW you guys know why Tip 2 is so damned important!!!!!!!! Tip 27 is even better to do.

 

Thanks vaustin79 for adding to this thread. 

Tips 1 through 5 are SUPER important as preventative maintenance on a Renix. You just flat do them BEFORE you experience problems. . 

 

Couple hours at the most if you're a slowpoke.