A bit if a strange one, I took the Daimler out for a drive in the evening for the first time in some months, and when I turned the lights on, the dash backlight came on for a few seconds, then turned off. Without it, you can’t see the speedometer at night. The behaviour was repeatable, turning the lights on means the backlight turns on, but after a few seconds, it switches off again. Any ideas on where to start with this one?

 

Likely your dimmer module is failing. Will the lights stay on if you turn the little knob on the left of the column to click into bypass?

 

Switching to over ride will bypass the dimming resistor (and going back into the dimmer module ) and be full bright

The next step would be the grounds

If more that one section of lights beyond the instrument cluster are effected it could help narrow it down

Stereo head ?

Climate control panel ?

See page 123 or 125 for long wheel base model

www.jagrepair.com/images/AutoRepairPhotos/jagxj1996.pdf

 

Similar problem here

Speedometer backlight not working - Jaguar Forums - Jaguar Enthusiasts Forum

 

Tried to do a bit of fault finding this evening, but everything was working fine. At least if it does it again I’ll know to look at the dimmer switch (which embarrassingly I didn’t even know was a thing).

Thanks for your help, I’ll post again here if it happens again, and how it gets resolved.

 

Problem came back, adjusted the dimmer, and the backlight came back on. I’m guessing the variable resistor (I assume that’s how it works) is broken.

Thanks for the tip.