Hi all,

I have a 94 JXS Convertible. It's temp gage would read erratic then eventually just bury itself on the far right (sounds so conservative) upon start up. I replaced the temp sending unit and not it just goes straight to the red even when just starting it up and cold.

I suspect an electrical issue. Can anyone give me some ideas where to look??

Tony in NM

PS: Merry Christmas!!!!

 

Sounds to me like the sensor or the loom wire from it is running to earth. V12 or 6 cylinder car? Anyway, find the sensor, unplug the loom from it and see what the gauge does.
Greg

 

Interesting that you should ask.

When I first got the car, the gage was eratic. It would bury itself to the right. Then, once warmed up, it would settle to about a quarter way left. Then it would do nothing, then back to the extreme right.

I found that the sending unit had a loose connection that seemed broken. I replaced it and now mostly get only extreme readings to the right of the guage. The car isn't overheating or running warm.

I have noticed since the weather has turned colder in NM that when I start up the guage stays in the cold area. The moment that a temp starts to register, the needle makes it trip to the right again.

Tony

 

Had a similiar problem. Ran an extra ground from the flexible circuit board and the problem was olverd/

 

By flexble circuit board, do you mean that gold covering on the back of the instrument cluster??? Could you give me a little more detail in how you did it??

Thanks,

Tony

 

Maynard may well be correct, but it is worth renewing the sensor and checking the wire as far as you can in the engine bay for cracks etc, before you get at the cluster.
Greg

 

Yes, I mean the flexible gold thing on the back of the panel. It was not hard to find a place where the printed circuit was carrying the ground. I took a length of wire, put an eye on each end, and connected it under one of the nuts holding the circuit board. The other end was connected to the chassis. I made the wire long enough to make it easy to pullout the gauge panel when necessary.

 

Are you certain the sender is the correct part? It is behaving more like a thermo switch than a gauge sender.

 

HI all,

I took my 94 XJS on its longest most demanding drive last weekend. It was only a 50 mile trip to Santa Fe, NM for the Zia Regional Rodeo, but it was the longest trip I've taken with it since purchase a year and a half ago. The car did great!!!!

One issue I have had, however, seemed to go away after getting on the hiway. My temp guage usually plants itself to the far right almost instantly. On this trip, it appeared to give me accurate readings. It set right on the "N" with a very slight increase when I moved up an incline.

Can anyone tell me what might be cause it to NOT work for so long then out of the blue be fine??? I am going on a Jag CLub picnic later today. I'll be interested to see what the guage does today.

Thanks,

Tony

 

Whenever I hear about weird electric glitches "dirty or loose connections" is what first comes to mind.

In your case though, with the gauge pegged, I agree with previous remarks that it sounds like the circuit is being fully grounded. I'd look for a chaffed wire that, via ordinary engine movement, has flopped into a favorable position....for the time being, at least...where the strands are not grounding out.

Cheers
DD