Having just replaces the upper and lower tensioners, guides, chains and waterpump and upgraded to an ally thermostat housing I was looking forward to a summer of care free top down fun. But..

My background illumination on all the dials and the centre consol buttons (those controlled by the dimmer) are now doing this:-

Ignition Key at I + Light Switch on or Off = Internal lights ON (all ok)
Ignition Key at II + Light switch Off = Internal lights ON (all OK)
Ignition Key at II + Light Switch ON = Internal lights OFF (Not OK)

This means when I drive I have a choice of external lights (which all work ok) or clocks and centre console.

I have checked all fuses and disconnected the battery for an hour. The wiring diagramme indicates that all the failed lights are under dimmer control.

The Odometer and AC LEDs apper to have 2 settings with the lights on; Full on with the dimmer all the way on until it clicks, or Low at any other dimmer setting.

The only other clue is that a lamp has just blown behind the rev counter.

It sounds like it could be dimming module, but any other ideas would be appreciated.

thanks

 

Does the dimmer variable dim function actually work in the modes when the inside lights are on?

 

Hi Steve

I was hopping a logic problem would grab your attention !

Just been to check (its easy at midnight) and no the dimmer does not work. But from memory I think its only supposed to work with the lights on with the ignition key in position II. Perhaps you could check this out on your car.

regards

Paul

 

Just hopped on a plane....so get some sleep and I'll check it out tomorrow if someone doesn't beat me to it.

 

You are correct...my car behaves this way. I would say check the red-yellow wire at the dimmer module with a multimeter in ignition II with the lights on. It should have a few volts on it. If it does, the problem is likely the dimmer module.

Only if it shows no voltage, then check the resistance to ground of this same wire with the dimmer mdule unplugged, (still with ignition II and the lights on). If it is less than 1 ohm or so, there might be a problem with your lighting stalk switch, otherwise it is probably a dimmer module problem.

 

Hi

Thanks for this

The red-yellow showed only 0.1V. Did not do the earth test as I discovered:

At the Dimmer Module:-

In Ignition I and lights on there is 12v at the Brown and Purply supply and Red & Orange (serving the Dials). But When I turn to position II not only does the Red & Orange Lose Voltage (supply to the dials) but so do the Brown & Purple supplys. So I wonder if there is a short/ earth fault on the Red & Blue (Radio Roof and Transmission) or Red & Pink (Rest of Dimmable Lighting).

I had the centre console out last weekend so I think Ill start there.

Buy the way I obtained a dimmer control from a scrap XJ and it showed identical switch logic on the overide and on the potentiometer, as the fitted contriol, so I ruled that out.

Also as my external lights all work as they should, does that not rule out the lighting stalk switch?

Thanks for the help, I may be back for more if this does not work.

Regards

 

OK, time to take a fresh look with this information.


If you are losing power on brown/purple, your audio system is also not working in IGN II when the lights are on, right?

I am scratching my head on this one, because the brown/purple is an unswitched battery source, and if you had a short, you would almost certainly blow a fuse.


(BTW, there is a second set of contacts in the stalk that signals the dimmer that the headlights are on or off, that is why I had some suspicions there.)

 

there have been some suspect stalks on the earlier models. I know a 99 isn't introduction year, but possibly a quick swap with a donor stalk would prove useful.

 

The line to the audio is only for illumination and as I have an aftermarket unit its not in use (I have also disconnected this unit to ensure its not the cause).

I thought the same on the fuse, but wgen I go back to I on the ignition key the power comes back and the dial are all lit.

If I can't find anything in the centre console I thing a lighting stalk or a dimmer module will be the next suspects.

Having Looked at my Audio layout It looks like I had (or the ISO blocks had) -poor excuse wired the Dimmer Overide (Red & Light Green) into the after market audio units dimmer wire (which I assume should have been the Red and Blue).

Its also very strange thar the LED screeans for the odometer and the AC are fully backlit with the dimmer switch on overdide and fully off on any other setting. Even when the other lights have failed.

 

I have been through the centre console and the centre console in detail and can find no wiring issues.

I also tried a hard reset.

I think its the dimmer control Module or the switch.

Also does anyone know the wattage of the illumination light behind the Taccometer, I tried a 5w (W5W) and its much to bright.

Regards

 

I made a note, in my Jaguar folder, a while back - someone in a post said that a 12v 3 watt bulb gave the correct brightness.
Have not tested this though!

 

Update

I have now changed the Dimmer Control Module and Dimmer Switch. To no avail.

I suppose the switch stalk is next. Luckerly my garage has a donor XJ8 and its the same part numbers!

But to add to my troubles I was planning to change the rear shocks but as of today the rear left is making a very worrying metal on metal noise on every bump and the rear end feals like its held on with an elastic band (I thought the gearbox/ drivetrain was collapsing).

My Jag Tech tells me the shock has probably broken, which he informs me is not unherd of.

regards

 

Might be a combination of a failing shock absorber and your bump stop rubber may have come away.

 

Doh. I have to admit a schoolboy error. I was reading the LHD fuse box location and checked the wrong 10A fuse.

Sorry for taxing your interlects for no reason. (I wish the wife had not just read this as well!!!!!)

It was just a blown fuse caused by a dash bulb blowing.

Im now off the eat the worlds biggest humble pie and stand in the corner for the evening.

On a positive note the parts I fitted were just borrowed from mg Jag specialists so no money lost. But they will have a good laugh at my expense.

It also just came back from the paint shop, to remove a little rust from the rear arches, plus a full polish.

Just need to replace the rear shocks on Friday (one is broken) and were off.

 

Glad it is sorted Paul. Here is to your honesty and humility.