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Well, I've been running the new motor for nearly a week and am trying to sort out the initial glitches. (of which there are a few).

When I bought the car the temp gauge read low - just above C which I guessed was a stuck thermostat. I fitted a new one and the gauge then read between N and H and fluctuated.........sound familiar Michael and Brian?
Laser thermometer indicated spot-on 88 degrees C at the thermostat housing and top right hand of the rad, so temp all OK.
The temp gauge on my black car always reads a rock solid low N so I swapped both of the sender units over (both red-top units).
Black car now reads solid high N. New car now reads mid N and fluctuates a little to high N.

From this it would seem that the sender unit can affect the reading (presumably as a result of age?) but is not responsible for the fluctuations.

Interestingly the fuel gauge reads accurately initially but rapidly falls. It reads accurately again at the start of the next journey but then falls away again. I have checked consumption and it is spot-on 25mpg so no problem there.

I remember from my Rover days that there was a voltage stabilizer connected to the back of the fuel and temp gauges and when it failed both gauges would do very strange things - is there a similar item on the XJS?

Also the battery voltage gauge kicks when a load is applied eg apply brakes - to me this would indicate some kind of earth fault? Is there a separate earth for the instrument panel and if so where is it located?

I would appreciate any suggestions from you Forumites as whilst these are minor snags they are a little annoying!

I will post photos of the mouse nest when I have taken them..............

Regards

Tony

Hi Tony

I look forward to the solution to your little niggles so that I can fix them on my car too.

Have a nice day

Tony

I think the last Jag to have a separate voltage regulator for the instrument pack was the SII XJ. It was deleted from the SIIIs and I think the XJS kept more or less in step, circuit wise. There's nothing of the sort shown on the '95 instrument circuit diagram.

All of which is no help diagnosing the problem. Dry joints on the pcb, possibly?

Tony,

I'm amazed you managed to last so long on your Black Beauty without suffering the inevitable anomalies of XJS facelift minor gauges!

The gauges seem to be very sensitive to sensor variations. I actually find my temp gauge very sensitive to even slight changes such as the load imposed on the engine by aircon running. If I go down a long motorway decline, I expect the tempt to drop by a few degrees and if I sit in traffic with the aircon on, I expect a minor rise. It might be that my rad is struggling but I actually find it quite encouraging to think that I'm seeing real-time changes in the gauge.

I've also never agreed with Jaguar's policy to fit a revised "fixed position" oil pressure sensor which is why I have one of the original variable sensors on my car.

As regards your fuel gauge and it's habit of dropping rapidly, mine started doing that about 18 months ago. The thing that makes me think it's electrically related is that if I turn on the ignition after filling up and wait before starting the engine, then the gauge will go almost all the way up. However, if I start the car quickly then it doesn't go up as high???

Considered opinion seems to be that it could be the "anti-slosh" module which is fitted in the boot. At £70, I'd find a used part or live with the problem.

Your problem is that you've had it lucky for too long! Welcome to minor gauge XJS motoring!

Cheers

Paul

Mine also does this I just thought this is how the guage worked (done it for six years now). The benifit is that it stops you running out of fuel unless you take a brave pill and wait for the low fuel light to come on as I have no idea how far you would get from when it comes on.

Does anyone know out of experience or how much fuel is left when light comes on.

Regards Mark 93 4.0 (Now with dodgy fuel guage).

Hi Both

Yes, Paul I guess you must be right, I've just always been used to the gauges working properly, I can live with their little idiosynchrasies but would like to know why they don't work properly.

One of the first jobs at service will be full cooling system flush and re-fill with 50% anti-freeze so we'll see what it does after that.

Mark re low fuel light I think the answer is LOADS! When I took the tank out of my 3.6 there was about four gallons left when the light came on!

Regards

Tony

Mark

Ref the fuel warning light, mine usually comes on at between 14.5 and 15 gallons consumed from full and without taking any brave pills I have got to 18 gallons consumed.

I don't do this any more as the car is quite hard to start on my downward sloping drive once fuel gets to this level but my guess is that there are about 5 gallons remaining when the light first shows. (Which makes the hanbook's info look a bit silly)