Well through my vast searches it seems i need a new speedo transducer, my speedodometer works sometimes but, what makes no sense to me is that whenever the speedodometer works or not works the temp guage coincides.
This baffles me, anyone know the reason these 2 work together??

 

Flakey instrument readings are common on XJSs....and the guages are none-too-great to begin with.

The usual fix is to remove the cluster and very gently clean all the contacts points on the (fragile) flexible printed circuit, the main connector, and the gauges themselves. Add a redundant ground wire on reinstallation of the cluster. Clean/replace the panel bulbs and sockets, clean the plastic lenses, etc at the same time :-)

Your particular problem sounds like a ground issue. On my XJS a poor ground caused the tach to go wonky whenver the headlights were turned on.

That said, the failure rate of transducers is high. It's entirely possible that you have a stack-up of problems.

Cheers
DD

 

Thank you Doug, guess i will start that project asap, before just buying a new transducer.
I'll clean and add a ground. My main concern is the temp guage going strait to HOT when cranking, and i know its not. The last thing i need is this not being fixed...

 

ok, i have the instrument cluster out and cleaning the contacts which i guess is the nuts holding down the plastic circuit film, where to attach the redudundant ground on the cluster????

 

There's a horizontal metal bar....can't remember if it's at the top or bottom of the cluster....you'll see it. Just run a wire from the bar to a known-good ground point under the dash.

Cheers
DD


PS- Here's trick to help ensure reliable operation: whenever you're working on the car take a few minutes to clean and tighten all grounds and electrical connection you find in that area. Or, take a Saturday and just go around the entire car and get it over with all at once. Don't forget fuse terminals.

The majority of the infamous, ballyhooed, and overblown Lucas horror stories will be solved! Repeat every 15 years or so :-)

 

yep i do remember seeing a bar on the cluster, i am using spray electrical cleaner on all contacts, will install a new ground & c what happens. Do you remember if the lights on the panel pull strait out or twist, thought about replacing w/ led's

 

Heh heh, yeah, you're really taxing my memory now :-). I think they're the twist-a-quarter-turn type sockets.

Cheers
DD

 

sorry, dont want to damage anything up there Just did'nt want to pull on those little
suckers to hard, to see how they fit. Now that i think about it i did'nt have a ground wire on that cluster anyway, unless its in the harness. More will be revealed soon. tks Doug

 

ok Doug,

cleaned it up, have'nt added ground yet. Snapped it back in---&--- a waa--la Houston we have lift off!!!

Something tells me you've been doing this a while.