Dielectric Grease or Bad Fuse Box

[CognizantPotato]

Hi everyone!

 

 I’m back on the forums. A last year I was having problems with my mj. I gave in after a while and took it to the mechanic. He replaced the ecu and fixed a bad wire.

 

Well that worked for a few weeks, until the truck died again and it seems as though the computer has suffered damage once again. The truck was acting odd with things such as blinkers not working, ac blower motor cutting out and then back on. I realized that me applying pressure to the fuse box and shifting it made things work every now and then.

 

After the truck quit I was too frustrated to do anything else with it and it’s sat for months. I’m finally getting around to trying to fix it, and fix it right this time. I’ve taken the dash out and have removed the sleeving from all the wiring. Whoever worked on this in the past did an awful job. There is duct tape in several places covering wires crimped together, so I’m setting about cutting and soldering to make sure my wires are clean and connected.

 

The fuse box acting weird is still making me concerned about it’s health though. I have attached pictures, and would love to get opinions on it. Is it simply old dielectric grease, or does it look like there may be some sort of corrosion? Any help would be greatly appreciated!

 

 

[Minuit]

That looks to me like old grease. It was the factory's method for sealing the connector, among other things. There's usually a lot more grease in them than that. I would suggest giving the terminals a cleaning and packing the connector with new grease. And I really do mean pack it with grease. That connector leaking water into the cab is a big contributor to floor pan rust, so you might just be killing two birds with one stone here.

 

Since I can see a clutch master cylinder, better make sure it has not leaked onto the fuse box. That is a very common cause of severe electrical problems on these trucks. It looks pretty new - why was it replaced?

[Minuit]

Looking closer at that picture: can you post a couple more angles of the center of both sides where the bolt goes through? The connector body looks a little molten to me. That makes me strongly suspect the clutch master cylinder leaked right on to it at some point.

[CognizantPotato]

10 minutes ago, Minuit said:

Looking closer at that picture: can you post a couple more angles of the center of both sides where the bolt goes through? The connector body looks a little molten to me. That makes me strongly suspect the clutch master cylinder leaked right on to it at some point.

 

[CognizantPotato]

I didn’t even notice the melting there. Thanks for pointing that out.

[Minuit]

I suspect that molten look is distortion from the plastic connector body being exposed to clutch fluid.

 

My 89 had a clutch master cylinder leak that badly damaged the fusebox itself, and the old fusebox had a similar look to it in places.

[CognizantPotato]

How did you replace it? It looks like I’ll either need a new harness or need to splice all the old wires to a new box.

[CognizantPotato]

3 hours ago, Minuit said:

I suspect that molten look is distortion from the plastic connector body being exposed to clutch fluid.

 

My 89 had a clutch master cylinder leak that badly damaged the fusebox itself, and the old fusebox had a similar look to it in places.

Do you think that this would work as a replacement?: https://www.summitracing.com/parts/prf-30001?seid=srese1&gclid=CjwKCAiA1eKBBhBZEiwAX3gql9aC11_aWGMkK-GcoUZDxQJ2L2gB89to3ffV0kq9_q3Vcqi8bYDdohoCM_EQAvD_BwE

 

I feel like I'm going to have a hard time finding an mj/xj around here to get parts from.

[ghetdjc320]

I know painless carries the actual fuse block with the bulkhead connector on it also. I I stalled their YJ kit and it had the same connector as 91+ XJ/YJ/MJ

[cruiser54]

Spray it out with Brake Kleen. Put a teeny twist on the male spades and put it back together. 

[CognizantPotato]

Thanks for the tips guys. I think I managed to find and label most of the suspect wiring, so I’ll be trying to improve that a bit. I’ll also be trying to clean the fuse box soon. I’ll update as soon as I have any news to share.

[ghetdjc320]

I prefer to use electrical contact cleaner and then run a strong magnet near the contacts while it’s all wet with cleaner. That picks out any metal shards or filings that may have found their way into the connections.