-91 XJ40 dash lights completely gone
 

One of my Kitten's quirks, after winter storaging the dashlights are completely gone, only radio and clock have lights.

I have checked the fuses (none blown and I think I found even the one that is for the dash lights) and few bulbs, those are all ok.

Any ideas? easy fixes? I am not an expert on car electrics but it would be fun to see speedometer etc in the dark too.


Kay

Key,

Are you certain that the display dimmer switch wasn't accidently moved and set at it's lowest setteing: (Item 4&5) It's located below the lighting switch for the exterior lights, on the steering column.

https://www.jaguarforums.com/forum/a...ine=1396716342

Seems odd you would lose all lights except the radio/clock at once.

Just to be clear, you're stating that all other instrument lights have gone out, such as the instrument cluster(speed, tach., fuel, oil) and the lights on the AC control unit, exterior light switch illumination are out and the gear shift indicator lights are out.....am I understanding you correctly?

Thanks Rob,
that was my first thing to check (the dimmer switch ), I think the gear lever light works but no instruments or ac etc.

I have exactly the same problem on my recent purchase

I would be pulling the dash cluster out and checking globes....
I know it is a long stretch to think they could all be blown, but when I got my baby... that's exactly the reason for no instrument lights....

mine however has the digital dash and the instruments were still lighting... only the speedo and tacho and backlights were off.
I replaced the globes and presto.... I had a lit up display.

you could also check the connectors going to the instrument panel to make sure they're all making good contact..... on my girl there are 4 bunches of wires going to the panel.... these cars do seem to have a problem with corrosion build up after sitting for awhile. if you pull them apart and give a spray that just may help.

Red, like I said in my original post... I checked few of the bulbs (globes as you say) and they were ok, no light anywhere though.

Gone through a few things already so I am guessing it is either the dimmer that is toasted or then there is a fault in the light logick switch

So I had my Kitten out for a drive and I think I found the fault, my kitten's parking lights and tail lights are gone too.

so this blonde would guess that it is the light switch module .... Question remains, is it easy to fix or should I order a new one?

Kay

Kay,

I'm traveling and away from my manuals, but if anyone has the electrical schematics perhaps there is a common relay or bus in fuse box that serves all those lighting circuits. Can anyone check the schematics for Kay? If not, I'll be home late tonight and will have a look.

Cheers,

Don

I am not home either so there is no real rush with this, I do have electric diagrams on my home computer so I will look into that when I get home.

Thank you so much Don

Kay,

I think you are onto the correct components, that being the dimmer and/or the lighting logic pack, however there is one additional component which also runs common on several different lighting schemes, that would be the Aux Light relay, which also interacts with the dimmer and lighting switch pack. It is located under the knee panel on the passenger side.

I'm not an expert at schematics, but have been forcing myself to learn how to read them. I examined the following schematics for the following systems for a 91 MY:

Side lights;tail lights
Interior lighting
Instrument lighting; locate lighting, clock

Aux light relay:
Pin 85 (blue/orange) runs a connection to the dimmer, lighting switch pack and "lights-on" audible warning module.
86 is battery power
87 is logic earth
30 is supply to side lights/tail lights, interior lights and cigar lighter lighting relay.

Dimmer switch
LB55-13 (red/pink) is a connection that splices and feeds the lights for the center console switches, lighting logic switches, speed control computer and the climate control panel.

LB55-4 (red/orange) is the feed to the instrument cluster lights

LB55-9 is the pin for connectivity to the Aux Light relay (pin 85) (Remember this has a splice in it for connectivity to the "lights on audible warning module" and the lighting logic pack)



You might pull both the lighting pack and the dimmer and examine all of the connections from the connector pigtail that terminate on each respective boards and any other solder joints.

Last summer I had to pull my Lighting Logic Module (pack) and found poor solder connections on it, it was causing a parasitic drain driving the lights on module on my vehicle.

A few questions;

When you have the lighting logic in position 2 (parking lights) and the door is opened, do you get the audible lights on warning?

I'm assuming, because you didn't indicate other wise, that the headlights are working properly, correct?

Are the indicator lights for the gear selector working properly? Are they illuminated, is sport mode illuminated?

Note: the aux light relay is in the black base, it also appears that the cigar lighter relay (white base, same location) is identical to the aux light relay. You can probably swap them temporarily to see if it makes a difference in the lighting behavior. Examine carefully before inserting.

Rob, thank you so much for all that trouble.

Question one, I did not try that last night when I got home. Will do that today.

Question two, yes the headlights work ok, even the high beams. (I did use the fog lights to illuminate the tail last night and they work too)

And three, yes gear selector light works as it should, my Kitten does not have the sportmode switch in it.

Kay

(and now I need my morning coffee)

Kay,

Based on your answers, I would concentrate on the Aux Light Relay and the Dimmer switch. There is no direct relationship between the dimmer and the gear indicator lighting, so it reduces the lighting logic pack from being a prime suspect. Further, there is no issue with the head lights or the fog lamps.

Your welcome for the help, it actually helps me hone my skill at reading the schematics, so I didn't mind the exercise.

Checked out the audible warning with the (non working) parking lights on... No sound what so ever, and neither with the lights on full. Hopefully I have time tomorrow to check out the relay, working lights in a car are quite nice after all.

Kay

This is a known problem with the XJ40. Happened to mine too.

Remove the light switch on the column. Disassemble carefully. Do not lose the ball bearings inside.

Clean the contacts well.

Reassemble.

Bill

Thank you so much guys, now cross you fingers that I do not make a complete mess out of my Kitten's electrical system.

I am not going all girly here but I do have serious doubts will I actually do something good here or just mess things up.

Kay

Kay,

It is always prudent to remove the negative cable from the battery while removing/replacing components..... no harm in risk aversion tactics, just a little more time.

You should be safe removing/replacing the relay without the battery connect/disconnect process, just ensure the car is not running, key either out of ignition or in the off position.

You Go Girl !!!! :icon_clapclap:

PS: I don't know if you have a stock radio that has a security code, but if you do you will need it to reset the radio when you reconnect the battery.

Light switch module pulled out and examined and refitted, I really cannot see any problems with that...

I do hope it is the relay that is giving me grief

Kay

Jag Bill are there any other threads/forums which talk about this, and the relation to teh light switch? Mick

Update,

I checked the relay possibility by swapping relays, no luck there.

So now I have examined the "Light logic module", pulled it out and looked for bad solder joints as ppl have told me to. cannot find any.


I attach pics of that board here so if someone might see and pinpoint the possible problems.

Kay

The help that I got for the light switch was about 15 years ago on a differant forum. Considering that it is a free and easy fix, I highly recommend cleaning the switch before tearing up any thing else.

Bill