So yesterday I pulled the instrument cluster to change the bulbs. I don't see much difference at all if any. Still looks like tachometer doesn't light up at all. The car has been pretty decent since i acquired it two weeks ago.

Took it for a drive today and it became possessed:

1) turn signals didn't work in the front or the rear, didn't even hear the clicking noise coming from the dash when the signals are turned on...totally dead.

2) the speedometer didn't even twitch...dead. Although we parked for a while and on restart the speedometer seemed to work fine again.

3) reverse lights dead?

4) worst of all....after about 20 minutes in stop-n-go traffic and 3o minutes to drive 3 miles....the car temperature gauge began to rise pretty quickly and got as high as 3/4 of the way "hot". It was the first time that had occurred.

I'm so frustrated and worried. Can anyone offer any advice on troubleshooting steps?

 

Do you have the wiring diagrams? I cannot recall the details but by the sound of it you have disturbed some of the connections for the instruments etc. If you haven't got the diags PM me with you email and I'll send pdf of the relevant diagrams.

 

heres a tip. anytime you touch anything electrical on these cars, make sure the battery is unplugged.

 

Used XJSs usually require sorting out. No need to be worried. Some frustration is acceptable :-)


If the speedo was working before changing the panel bulbs I'd say you probably damaged the printed circuit when taking the cluster out or reinstalling it. That's not a criticism. The printed circuits are very fragile and it's very easy to accidentally damge it. Remove the cluster again and check.

The temp gauge reading high might be the same situation and the gauges are known to be flakey anyway. But, then again, maybe not. These cars have marginal cooling systems. More on that in a minute.

The signals and brake lamps might be separate problems. As mentioned you'll have to use the wiring diagrams to make some checks. One quick trick on the signals: power for the turn signals comes from the emergency flasher switch....which often has dirty internal contacts from lack of use. Sometimes vigorously exercising the emergency flasher switch clears the dirt and restores power to the signals. I've "fixed" a few this way.

Back to running hot....

FIRST, find out how hot it's actually getting. Use a hand held infra-red thermometer to check the temp readings at each thermostat housing. A reading of about 190ºF should be about middle-of-the-N on your temp gauge...though I've seen quite a variance in results here.

Assuming the temp gauge is fairly accurate and the cooling system does have a problem........

Did the temp come down once you were able to regain road speed and get air flow through the radiator? If so, I'd suspect a faulty fan clutch. Common problem.

Another very common problem is a clogged radiator ...not only clogged internally but externally as well. It's common to see 30% of the face of the radiator totally clogged with debris. Best bet is to remove the radiator to blow the junk out. As long as the rad is out, though, you might as well have it professionally cleaned at a radiator shop.

Overheating is a bugaboo on V12s. Generally speaking, though, a clean radiator, new fan clutch, good (and correct) thermostats will do the trick.....IF the system is properly bled after the work is complete. Proper bleeding is essential and sometimes frustrating.

All that said, even in tip-top shape there isn't much reserve cooling capacity to these systems. If ambient temps hit 85ºF-90ºF and you're stuck in gridlock traffic for 30 minutes, the temp needle WILL begin to rise. Increased temp, to a point, isn't much of a concern if it stabilizes. If it just keeps climbing and climbing with no end in sight, well, that's not good.

Cheers
DD

 

If my temp gauge was reading that high, i would be getting out and checking the rad pipes with my hands or an infrared thermometer to confirm.

 

Thanks for the advice Doug. Embarrassingly enough, I've always had new cars and never had to deal with these issues so pardon the stupid questions that are about to follow. In fact I should include that in my signature....lol!

Can you explain what the printed circuit is? If pull the cluster out again, what exactly am I looking for? How would I know if I damaged it?

Ok, so here are some details I forgot to mention. the front signals turn on and remain on at night (like driving lights), but don't blink when the turn signals are used. The rear signals don't even turn on.

You mention power comes from the emergency flashers...I assume you're talking about the 'hazards'? When I put the cluster back in, I tried to pull the hazards button off the dash by pulling it. I read in a post on here that you could remove those buttons by pulling them. The button came off but also broke part of the piece on the side of the button housing that acts as spring i guess. Now the button feels very loose. The reason for trying to remove the button was to check if there were any bulbs back there since all the buttons above the radio and below the trip computer are dark.

The temp began to rise as I was stuck in baseball stadium traffic. Once I got into the stadium, the car was parked for about 2 hours. When I got back in to head home, the needle was right at N as opposed to the bottom of the gauge.