Working under the instrument cluster a lot this week on the 91 classic collection xjs. I have reviewed quite a few different threads on the topic and have been unable to see someone replicating the issue I'm having.

The Speedometer is incorrectly reporting speeds between 10-45 mph - the speedometer shows around 50mph. Above 45mph it appears to be accurate (but a bit off). I also noticed the speedometer seems to actuate better under heavier throttle.

The tachometer is generally not working at any RPM, and won't fall to 0 on its own. If you tap the panel a bit it will fluctuate and seemingly catch. The heavier throttle also applies to the tachometer though, and when its pegged it climbs, but i still don't believe its happening accurately.

I believe these are intertwined, but it seems like the common fix of the speedometer transmitter isn't the culprit. I was wondering if anyone may have any ideas as to fix, as my current thoughts are around the actual dials and finding some lubricants for this.

 

Also working on the instrument cluster lights, and I've been unable to find a t10 socket that fits the rectangular hole. Anyone have a source for those too?

 

Have you done anything with cleaning the contacts on the cluster and potentially fitting a new ground? Corroded contacts can cause all sorts of problems.

 

Good point. I had the contacts off yesterday but didn't clean them up much more than brushing with a finger. I'll try that and report back

 

Testing grounds on all my instrument cluster and finding a lot of resistance around a handful of places. Will be cleaning over the weekend and hopefully have things sorted! However, still unable to find any replacement t10 sockets that fit the original size for the instrument cluster! Everything is twist and lock.

 

Buy a second hand cluster and use the sockets in that? Lots for sale in UK at least.