New Owner 1994 XJ81 V12
#83
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
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
#84
#85
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
Last edited by Parker 7; 12-12-2022 at 09:36 AM.
#87
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).
#88
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
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Lawrence (12-13-2022)
#89
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
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
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Don B (12-13-2022)
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