So the "Anti-Lock" and "Brake" lights have been on for a while (still getting around to diagnosing those problems) but I have been chasing an intermittent speedometer reading for a few weeks now. I have pulled the cluster out and cleaned the contacts and leads so everything has a good connection. Everything was working for about a week then this evening while driving the Speedometer would go dead, then wake back up, then go dead and wake back up, finally going off all together. However, I just noticed that the "Anti-Lock" and "Brake" instrument lights would both go out when the speedometer would drop off, then illuminate when the speedometer came back online.

Is this a short in the cluster, something to do with a speedometer sensor, or something different all together?

Any input would be much appreciated.

1992 XJS V12

 

Hi Sd

Sounds like you've got a bad earth and if so its not unusual to rig up a supplementary earth behind the Instrument Cluster

Though do make sure that all the Pins on those Multiplug Plugs and Sockets are absolutely clean with no corrosion in sight whatsoever, as this is one of the major reasons for the Speedo to intermittently fail as it has on your Car

'Grant' advises 'Lemon Juice' for this sort of thing, which can be applied with a 'Cotton Bud' and that was one of the things that worked for me and also be very careful not to damage the Printed Circuit, or that could be a very tricky problem to sort out

 

I agree with OB. I'd take the cluster out again and double check everything and add that extra ground. If no joy then start looking for something more esoteric.

Cheers
DD

 

Thanks Gents. I’ll give it another crack.

 

Good point, OJ, about the printed board. My printed circuit for the instruments and lights had burned traces. Bought trace material on Ebay. Trace materal is copper with adhesive on one side. Just stick it on your printed circuit and tack solder to complete the circuit

 

AB1, thanks for the advice. I’ll definitely keep that in mind if the ground wire doesn’t work or if I see any charred areas!