I was having issues with my fuel gauge going erratic on me. I pulled the control module out and cut it open with a utility knife. What i found were 3-4 cold solders on the circuit board. I resoldered and now my guage works perfectly. I'm guessing that a lot of issues on these cars specifically early 90s (mine is a 94) are due to bad solders on the control modules. The first culprit are the relays and then the modules.

the issue arises from the switch from lead solder to rosin solder around that time period. the solder is fine but people just did not know how to use rosin solder properly at the time. I believe it requires slightly more heat to melt properly. So its not just jaguar specific. I find that most electronics during that period get cold solder issues. In case you do not know, a cold solder is just when the solder cracks.

If you cant pinpoint your electronic issues, I would look at the modules and remelt any suspect solder joints. Save yourself hundreds of dollars. If your ECU is bad it may just need a touch o a soldering iron. If you buy an old stock ECU or module you could wind up with the same issue...

 

Great work!!
Not being so adventurous, I bought a new one and my gauge now works well......but I did save the original, and will try to do what you did. Just so we are on the same page, you are refering to the anti-slosh module located above the rear left tire in the trunk....it's black and looks like a tall relay, correct??

Thanks!!

 

huh? Are you rewriting history? Rosin core solder was definitely not something new to the nineties. Nor was it rare, esoteric or expensive. You just picked it up at the nearest Radio Shack.

Cold solder joints have always been a possiblity, but it has nothing to do with the type of flux employed. It is simply due to poor materials preparation, inadequate tools, or improper technique.

Perhaps you have the terminology mixed up with "lead free" solder which was mandated in the EU for RoHS compliance in 2006.

 

After some reasearch, clearly my knowledge of solder is completely wrong so disregard what I said about the types of solder used.

...your right. I was highly misinformed on this. I've heard from multiple sources that there are common issues with solder during the late eighties and nineties, in always thought there was a switch in solder during this time, though maybe it was more of a manufuacturing issue.

That said, I would check for bad soldering on a module, no matter what year, before you replace it to possibly save some money.

 

In regards to the actual fix...I have taken my old module apart, but I can not identify these "cold joints"...how do I know where they are?? ...Although my gauge is working now because of the new module, it would be nice to know how to fix them for future reference

Thanks!!

 

Hi, I just joined this forum -- where is this control module located? My '87 xjs fuel gauge is not working so I must begin my troubleshooting journey!

 

I have the gas gauge issue in my 1992 so I ask the same question, " Is it where Spikepaga suggests ? Above the left rear tire in the truck ?
Tx..

 

Apologies. I have found that the anti-slosh module is above the left rear wheel (in the trunk)
I also sourced a trouble shooting method for xj-s facelifts and their gas gauge issues which is contained in this large document.
http://www.terrysjag.com/XJS%204.0%2...Electrical.pdf

Cheers,
Gerry