Some time back, I had a problem with the headrest light on the driver seat
remaining on after all of the other interior lamps had extinguished. This
occurred a few times, and then went away.
It’s now back, with a vengeance. So much so that after multiple attempts
to get it to extinguish (which is a bit agonizing with the post door
closure delay each time), I ended up pulling it from the headrest and
removing one of the wires. Fortunatley I notice it in the evening, and
when I remove the baby from the rear seat, but during a daytime trip (or
worse, when the rains start), one can’t linger waiting to see if the light
is behaving.
It’s just the driver side one that is affected, and I’m wondering if
there’s any typical causes (duff delay relay?), or if I’m going to have to
remove the seat and go fishing for problems in the wiring harness (perhaps
it’s chafed someplace?).
— '88 Jaguar XJ-SC 5.3L V12 (LHD) ‘Black Cat’
Sean Straw '85 Jaguar XJ-S 5.3L V12 (LHD) ‘Bad Kitty’
Sonoma County, California '91 Jaguar XJ40 4.0L (LHD) ‘Trevor’ http://jaguar.professional.org/ '69 Buick GranSport 455 V8
Visit the Jag Lovers homepage at http://www.jag-lovers.org for exciting services and resources including Photo Albums, Event Diary / Calendar, On Line Books and more !
In reply to a message from sean.straw%2BJaguar@mail.professional.org sent Sat 22 Oct 2005:
I’ve had the same problem with both of my 88s. In one car, there
was nothing I could do to turn the light off (passenger side) so I
pulled the seat bottom up (there’s just one screw at the front
securing it) and pulled the plug.
On the other car, I found that there is a brightness control built
into the light, and it will stay on if it is adjusted. The light
will go off and on with the doors if the brightness control is on
the off position. I haven’t gotten around to checking the first
car for that condition, yet. Nothing in the back seat of that car
except old McDonald’s bags.–
Pete 70 XKE (193K) 88 XJ6 (231K) 88 XJ6 (213K)
Severna park, Maryland, United States
–Posted using Jag-lovers JagFORUM [forums.jag-lovers.org]–
–Support Jag-lovers - Donate at http://www.jag-lovers.org/donate04.php –
Visit the Jag Lovers homepage at http://www.jag-lovers.org for exciting services and resources including Photo Albums, Event Diary / Calendar, On Line Books and more !
Are you sure the light isn’t left switched on? It’s easy leave on
accidentally.
Otherwise there are two causes I can think of:
The switch is bad and staying closed all the time.
There is a diode in the wiring which could have shorted out.
If you are handy with a voltmeter, it will be easy to spot the cause. The
components are all there in the light assembly, so there will be no need to
pull the seat out.
David Hurlston
ViaData LP-----Original Message-----
Some time back, I had a problem with the headrest light on the driver seat
remaining on after all of the other interior lamps had extinguished. This
occurred a few times, and then went away.
Visit the Jag Lovers homepage at http://www.jag-lovers.org for exciting services and resources including Photo Albums, Event Diary / Calendar, On Line Books and more !
I take back the shorted diode part. That won’t cause the symptoms you see,
so either the switch is really on, or has failed on, or there is a short in
the wiring near the switch. In any event, the problem lies in the vicinity
of the light assembly so it’s easy to get at.
Are you sure the light isn’t left switched on? It’s easy leave on
accidentally.
Otherwise there are two causes I can think of:
The switch is bad and staying closed all the time.
There is a diode in the wiring which could have shorted out.
If you are handy with a voltmeter, it will be easy to spot the cause. The
components are all there in the light assembly, so there will be no need to
pull the seat out.
David Hurlston
ViaData LP-----Original Message-----
Some time back, I had a problem with the headrest light on the driver seat
remaining on after all of the other interior lamps had extinguished. This
occurred a few times, and then went away.
Visit the Jag Lovers homepage at http://www.jag-lovers.org for exciting services and resources including Photo Albums, Event Diary / Calendar, On Line Books and more !
In reply to a message from sean.straw%2BJaguar@mail.professional.org sent Sat 22 Oct 2005:
I had the exact same problem. After diagnosis by a Jag certified
mechanic, found the problem to be the central microprocessor unit.
Replaced that & everything worked as it was supposed to.–
WCManess - 1991 XJ40/6 Base - Black/Grey
Arlington/Texas, United States
–Posted using Jag-lovers JagFORUM [forums.jag-lovers.org]–
–Support Jag-lovers - Donate at http://www.jag-lovers.org/donate04.php –
Visit the Jag Lovers homepage at http://www.jag-lovers.org for exciting services and resources including Photo Albums, Event Diary / Calendar, On Line Books and more !
With respect, I don’t think you could have had the same problem. Only the
driver’s side stays on in his case. A failure of the processor would cause
both to stay on.
David Hurlston
ViaData LP-----Original Message-----
I had the exact same problem. After diagnosis by a Jag certified
mechanic, found the problem to be the central microprocessor unit.
Visit the Jag Lovers homepage at http://www.jag-lovers.org for exciting services and resources including Photo Albums, Event Diary / Calendar, On Line Books and more !
In reply to a message from David Hurlston sent Mon 24 Oct 2005:
I’m not sure of how it all works, but yes - it was just the
driver’s headrest light that stayed on. Passenger side did not,
and now they both function properly after the new CMU was installed.–
WCManess - 1991 XJ40/6 Base - Black/Grey
Arlington/Texas, United States
–Posted using Jag-lovers JagFORUM [forums.jag-lovers.org]–
–Support Jag-lovers - Donate at http://www.jag-lovers.org/donate04.php –
Visit the Jag Lovers homepage at http://www.jag-lovers.org for exciting services and resources including Photo Albums, Event Diary / Calendar, On Line Books and more !
Are you sure the light isn’t left switched on? It’s easy leave on
accidentally.
I’ve run the switch full throw both directions several times to no effect
('cept for the dimming). After disassembling it, it appears “full throw”
isn’t quite what I’ve been getting - the little contact wasn’t fully
detenting from the constant power source.
Otherwise there are two causes I can think of:
The switch is bad and staying closed all the time.
There is a diode in the wiring which could have shorted out.
Well, the curious thing is that the problem came and went before, so a duff
diode doesn’t sound quite right. I realize there’s a diode within the lamp
assembly - that’s obviously there to isolate the reading light from
backfeeding the courtesy light circuit.
That problem is resolved, and now I’ve another…
— '88 Jaguar XJ-SC 5.3L V12 (LHD) ‘Black Cat’
Sean Straw '85 Jaguar XJ-S 5.3L V12 (LHD) ‘Bad Kitty’
Sonoma County, California '91 Jaguar XJ40 4.0L (LHD) ‘Trevor’ http://jaguar.professional.org/ '69 Buick GranSport 455 V8
Visit the Jag Lovers homepage at http://www.jag-lovers.org for exciting services and resources including Photo Albums, Event Diary / Calendar, On Line Books and more !