Xantia Exclusive - Speedometer incorrect

[Fred du Plessis]

Hello Forum,
When I switch on the car, the speedometer jumps to 30km/h, even before the car is moving.
What can I do?
(Is there a calibration procedure? Not seen any on forum)

[Peter.N.]

Sounds as though there is some arcing going on somewhere. Does it stay at 30km/h or is it varying and does it work at all when driving?

Peter

[CitroJim]

It may be dodgy joints on the printed circuit board at the back of the instruments or else failure of the voltage regulator integrated circuit. The latter is, I believe, a standard sort of 5v regulator similar to a 7805 in a TO-220 package and can be fixed. A voltmeter will prove as there is enough cable length on the instrument connectors to allow it to be operated with it withdrawn for test purposes.

The other gauges can suffer erratic readings due to loose nuts on their fixing/connecting studs...

[Fred du Plessis]

Hello Jim,
Thanks for your explanation. You are right, it should be properly earthed.
I was wondering to the remove the panel, as soon as I can stop the car ( If a printed circuit layout diagram is available, otherwise I would need some electronic sniffing), I have long cords for testing purposes, and multi-tester.
When I am doing it, I may be contacting you again, with a picture or 2.
otherwise, I like the car very much.
Thanks,

[Fred du Plessis]

Sounds as though there is some arcing going on somewhere. Does it stay at 30km/h or is it varying and does it work at all when driving?

Peter

Hi Peter,

No. Thereafter it responds normally, and goes to 100km PLUS, like normal, but just showing 30km faster than actual.

I thought to remove the panel, the glass, remove the indicator needle,switch on, and push it back onto the shaft (if I can not find a variable potentiometer on the circuit board), then test it, and re-install it.

will keep you informed...

[CitroJim]

Fred,

This is the speedo main PCB and the voltage regulator is the one on the large black heatsink. This one may be OK if all the other gauges are reading OK.



Remove the PCB by carefully disconnecting the ribbon to the odometer display by pulling uop gently on the top part of the black connector until it separates. The ribbon can then gently be eased out. Remove all screws and gently sqeeze the plastic clips that pull the board tight to the gauges and with care the board can be removed, leaving sight of the gauges themselves.



Note the gauges themselves make contact to the printed circuit board through four sprung fingers on each gauge. These touch 'pads' on the printed circuit as scan bee seen on this underside view:



Very gently clean the finger tips and pads, reassemble and see if the fault has now cleared.

I stress that board needs to be treated very gently as it is delicate, especially that ribbon cable!

Whilst the instruments are out it's not a bad idea to replace the bulbs. they always fail when you dismantle it

[Fred du Plessis]

Thank you very much Jim.

Since I started working on my Light 15 in 1972, I noticed motor engineering was advanced for their time (1930's) and here, again on the Xantia.

I will keep this near when I open up.

(want to tackle the dashboard items at one go, even looking into Speedo Cruise and Hydro-active switches-no response)

[JohnCKL]

I have a 1996 Xantia turbo diesel 1.9. When I start driving, the speedometer will quickly speed up to 72kph even though my speed is probably only 30kph. It will then stay there no matter if I go fast or slow until I slow down to a stop then it will quickly drop down to zero. Sometimes a sharp rap with my knuckles on the meter will drop the speedometer to the right speed but once it get stuck on 72kph, it will stay there. Sometimes if I go over 100kph, it will suddenly move up to the correct speed. I've taken out the meter cluster and sprayed some lubricant on the spring in front after taking out the needle but it doesn't work. Is there anything I can fix?

[RichardW]

John

This is a well known fault - in the UK it is 50 MPH! Mine has been doing it since I got it on and off - I just ignore it and drive on the tacho instead. Anyway, the cure is relatively simple, take out the instrument panel, and resolder the 4 pins that transmit the signal to the speedo - if you examine them carefully you may well be able to see cracking on them. Pins in question (courtesy of Clogzz):



Although it in turn appears to be knicked off this blog...http://www.schaalbouw.nl/citroen/blog051007.htm

EDIT:

RW Originally wrote: MK2 may look a bit different, but principle is the same - perhaps you can take the MK2 photo if you repair!

However, having looked again at Jim's pics, that's bollox

It looks like on MK2 there is a spring contact between the PCB and gauge - Jim, any chance you can provide a blow up of the photos at the critical location? Not sure what the fault is on the MK2 then - perhaps the springs just jon't give quite good enough contact, or they are corroded? Any thoughts Jim?

[CitroJim]

Not sure what the fault is on the MK2 then - perhaps the springs just jon't give quite good enough contact, or they are corroded? Any thoughts Jim?

I believe it's a combination of a bit of both Richard...

I'll try to do a blow-up of the contacts but for various reasons it won’t be very soon unfortunately...

[JohnCKL]

Thanks Richard. Will do so.