Hello, I have a 1989 jaguar XJS that I am restoring that looks like someone decided to leave the top down and then leave outside. I have done a ton of work to the car and it runs and drives great now! I have replaced a lot of the broken wires in the engine bay(The ones that get hot and crumble to the touch when they are worn out). I have also replaced the injector wiring harness. I have the dash and center console apart again as I have run into two issues that I do not seem to be able to fix. First issue is the top doesn't work and I am getting 5v at the switch. I have voltage at the fuse and it was working just a few weeks ago without issue. The only thing I have touched since is I have replaced all the set in trim pieces and center console trim. I doubt that would have any impact on a switch. The second issue I have and the most important one right now to me is I have a short to ground on the wires that run to the lighting rheostat. When using a multimeter set to continuity I get a beep when touching all the RW cables and the ground, yet I still see voltage on the line reading properly when doing a volt check. I have checked the wires going to the center console and the center panel. The short still exists with the instrument panel removed as well so I don't think it is there. When I turn the light switch on, it immediately flags a bulb failure and the Oil/Temp gauges go to max. The tachometer and speedometer cuts out completely. Any assistance/recommendations would be appreciated. Sorry if this was answered somewhere else, a quick search did not find it.

 

Sounds like you've done an impressive amount of work so far. Congratulations.

On the conv. top issue, when these cars aren't used regularly, the relays can get 'stuck' or possibly in your situation, corrosion is creating too much resistance. Try cleaning the contacts and swapping around the relays and see if that makes a difference. Sometimes a tap on the relay while you are holding the switch can work.

On the rheostat, I would recommend simply bypassing it. The instrument lights on the XJS are not bright enough to need dimming in the first place. See if bypassing either solves the problem or let's you more easily find it. Your other instrument panel issues sounds like a poor ground problem (search threads for how to improve the ground of the panel).

 

Thank you for your kind words! I was able to accomplish a lot of this work due to forums that I followed on this site.

I'll give the top a try later today after work. I know the windows go up and down like normal, I'll try swapping those relays over.

For the Rheostat, I get the same issue when I bypass it. When I connect the interior lights at all is when the issue seems to occur. Putting the probe from the multimeter on either of the RW cables and the B cable gives me a beep and shows me that I have a short somewhere. I just can't seem to find it. I have seen the threads about adding ground to the dash, I want to do that but I think it would be best for me to figure this short out first then add the ground connection.

 

Zalphyr,

If the rear windows are working up and down when you operate the hood switch, then it seems the problem lies in either:

- the fuse (the fuse is only in the hood pump circuit, not the rear windows)
- the Up and / or Down Hood relays (Try pressing the switch to raise the hood and see if you can hear the pump operating, which might help narrow the problem down to the Down relay). Check to see if you've got current on the output terminal of the relay.
- the hood pump itself. If you've got current at the output of the relay, see if you've got current at the pump when the switch is being operated.

Good luck

Paul

 

Sorry, my mistake, I thought the door's windows were back on that bank but they are not. I am also seeing voltage at the fuse and relays so I know that the relays are getting power, The pump does not make a sound. I know the pump is good as I just bought it and replaced the pump and hydraulic pistons last year. The previous pump was seized up. I tried tapping on the relays and it didn't work.