Powered by 2 different fuse panels so no 1 specific but do check fuses

 

Driver seat control / Left fuse panel

Passenger seat control / Right fuse panel

Cigar lighter / Center fuse panel

 

It turns out the left and right fuse panels fuses are hot at all times with no relay inside so never clicks

The ignition switch does enable a monitor inside the panels to come alive to show faults on the dash

The center fuse panel must have the ignition on relay closed which you felt the relay click then the fuses will be hot

The engine ECU ( EMS ) is powered when the EMS Main relay closes , this can be seen on figure 30 of the wiring guide

 

This is a bit difficult to understand to me. Are you saying the wipers do work OR not? I am asking this because it could be a hint into a specfic direction.

 

Editing

Something is wrong in the following text so will have revisit it later today

The wiper fuses are both in the Left fuse panel and the center fuse panel in the pic above

test the cigar lighter as this fuse is ibn the center fuse panel

This fuse panel relies on the ignition on relay to close powering the fuses in the center fuse panel

This can be seen on page 19 of the wiring guide and the cigar lighter is point X on the right side of the print

Cigar lighter is fuse C! center fuse panel , and point 72 square page 55 before the cigar lighter relay so complication in putting things together

If the relay clicks with the ignition key rotation, then swap it anyway as the power contacts inside the relay can be burnt limiting the current to properly run the devices from the center fuse panel

Swap the relay with one of the same part # like maybe a headlight

 

The OP's problem is sounding more and more like a fuse box issue. Fuses will test good across terminals in a faulty fusebox - the circuit boards in the rear are extremely prone to cracked solder joints.

Just my 2₵

Larry

 

I found the fuse boxes to be of good quality on the late cars, no faults there. I suspect two possible causes for this particular fault pattern. Either some ground fault or a defunct central body processing unit. I have been there and have traced the issues myself. And got it fixed by replacing the BPU (I had 2 spares...).

In order to get any further on this, we will need firm results from checking fuses and which electric components do work or not. And the OP needs a multimeter (and use it).

 

Hi newyankee, I don't know what you consider to be the "late cars" in the XJ40/XJ81 range, but the fuseboxes in our '93 and in Larry's '94 had cracked solder joints on the circuit boards, so that could certainly be part of the OP's issue.

You mention grounds, which are definitely an issue on most Jags. I've developed habit of disconnecting and cleaning any ground in any area where I'm working on a Jaguar just as good preventive maintenance.

The battery power connections are also prone to corrosion so cleaning those can often resolve mysterious issues.

Cheers,

Don

 

From what I've read about other member's cars and my own experience, I would say the late cars are the worst offenders!

When I first discovered the fuse box problem, the heater blower fuse had tested good.
I had continuity from either side of the fuse holder, but due to a cold/cracked joint in the rear circuit board, that was as far as the power could go. The brown/blue tracer wire leading from the fuse box to the blower (which is normally powered even with ign off) was dead.

In my case, re-flowing the joints on the uppermost board solved the problem. Other owners have had to go deeper, separating the two boards and reflowing all of the joints.

I'm not saying this is the OP's problem, but just because fuses test good and continuity is found across the fuse holder terminals does not guarantee all is indeed OK.

Larry