Hi all, recently purchased a '98 xjr, has been fine until a week or so ago when the headlights and instrument lights flickered, since then it has knocked the headlights out, comes up with traction control fail, stability control fail and today has refused to change past 3rd, turning off and on again worked for a bit but even that hasnt helped recently, any ideas?, have searched on here and thought it may be a ground fault, removed and cleaned up all 3 connections under the bonnet but to no avail.

 

It also could be the B+ feed from the battery to the engine compartment fuse panels. There is a through connector on the right firewall extension feeding the panels that has a history of corrosion and failure.

I assume that you have done a load test on the battery (?).

 

Another place to check is the engine grounding strap, from the frame rail to the transmission bell housing. Remove, clean up all surfaces with scotchbrite or sandpaper, etc, and reinstall.
If you have a voltmeter you can test for a problem by connecting one lead to the engine block and one to a chassis ground while it's running. If you have more than about 0.5 volts, the strap needs cleaning.

Be sure to check out the connector Test Point is talking about, mine was loose.

 

Hi, thanks for your replys, just got around to checking the battery under load, it goes up to around 18.7v, also the positive lead direct of the battery is getting v warm and the battery hissing

 

Oh, that sounds interesting.....tested your alternator yet? It should be pumping 14.5V +/- I see a new battery on the horizon...how are you load testing it?

 

Its over charging. Check the bulkhead fitting in the ecu coolbox under the hood. They get hot from looseness and overheat and melt getting even looser. Just replace the ground strap from engine to frame. They never look bad. But if youre having issues consider it routine maintenance, they do fail alot and cause alot of electrical issues. Is the battery water up to corect level, if the plates inside are uncovered from the water being too low. Replace the battery, if you top it up it will be dead shortly there after. Been there done that. If i have a customer with uncovered plartes i replace the battery, ive had more than a few return a few days to a week or 2 later with a dead battery. Just dilluteds the electrolite too much