Hi all,

I recently purchased a 1989 3.6 xjs as it is a jag that my wife and I have always liked and we came to the agreement that we would let her x300 and my series 3 go to have a shared xjs project.

The car is running mechanically sound -for a car that'd been standing since 2009...- and remarkably it doesn't have much rust. It does however have the usual Jag issues aka Gremlins everywhere, which I am trying to kill one by one now.

The first one that I sorted was all the panel lights, as 90% of the bulbs were gone and the dimmer was not properly connected so nothing worked. Electrically, the things that I am not managing to sort our are:

- Tacho: The speedo works perfectly fine but the tacho stopped at 65k two years before it was put off the road...any suggestions? One of the two bolts that secure the fusebox under the drivers' side (UK car) seems to have the remains of what must have been an earth, but it is not there anymore and there is no black cable hanging.

- Temperature gauge not working at all. Which is the sensor? I understand that the 1 pin is the temp sensor for the ECU, and possibly the 2 pin is the one for the gauge? Any light on this or previous experiences would help a lot.

- My xjs has one of those old school clocks. The purple wire going into it had no power, and I conveniently found another purple hanging under the dash which had continuous 12v even with the ignition off. No brainer, I soldered them together but the clock is not having any of it. When I connect the wire it reads 5v instead of 12, which I guess means the clock is draining something. Has anyone seen this before or do you have any links to how to take the clock to bits? I don't seem to find the way of accessing the internals.

- The biggen is the AC-heater blowers. When I turn the controls I can hear valves and actuators, but the fan motors are doing nothing. On the left footwell I have found a yellow wire with black dots which is hanging, but can't find it in the wiring diagrams. On my series 3 this problem was always the 4 in 1 relay, but my xjs seems to have a fancier system...ideas?? Really lost with this one.

I think that for now that's about it...the car feels much better than when I bought it, and it's one of those where every little thing I do makes a huge difference. Can't wait to fix these bits!

Cheers,

Miq.

 

Instrument problems on the XJS are often caused by dirty contacts at the cluster connector and the contact points of the flexible printed circuit attached to the backside of the cluster.

Remove the cluster and clean all the contact points....and add a redundant ground/earth wire .




Other way around. Single wire (usually green on old Jags) is the temp sensor for the gauge. With the key 'on', touch the wire to ground....the temp gauge needle should go to the top



You have the Mark III system....yes, fancier than the earlier type.

Checking that both fuses are OK, if you haven't done so yet, will be the only easy part of this problem, I'm sorry to say.

The blower assemblies each have a circuit board with a transistor, relay, diode, etc. These are all often rotted out. The circuit boards are DIY rebuild-able but removing the blowers is very unpleasant.

The climate control also suffers from dirty or corroded connectors, especially if the dashboard area has been exposed to moisture from a windshield leak. When you remove the under-dash panels, and console cheek panels, you be able to see and track down most of the connectors....recognizable for being very small and having very small wires. A couple are wayyyy high towards the windshield. You have to open 'em all up and clean 'em. Also, remove and clean the system ground/earth wires....which can be easily found the on the vertical sheet metal dashboard supports.

You might get lucky and find that cleaning the connections brings things back to life.

Others will chime in with more.

Cheers
DD

 

Here's some info on the blower motor circuit boards....in case you end up having no choice but to dive in

Air conditioning blower control


Cheers
DD

 

Nice one Doug, thanks a lot for all the info. I will try the sensor tip later tonight.

Yesterday I took all the panels apart and sorted the obvious, but didn't get as far as cleaning all the connectors, etc, so that's a "to do" for tonight (I am using the car so had to put all back together...).

The clock started working with the engine ON, so I am assuming it needs a stronger 12v feed, I will check some of the ones that go to the radio or cigarrette lighter.

Thanks again, will keep you posted!

The breaks also feel a bit spongy although they are all new, so I will start with bleeding, however, I am not too familiar with the "servo" system that these cars have (reminds me of the ones in the xj40), so am wondering if it could be a vac leak on the servo.

ta

Miq.

 

Follow this thread to post #19 where you'll find a link to a Delanair Mk III technical manual

https://www.jaguarforums.com/forum/x...-manual-83961/


Cheers
DD

 

A 1989 XJS will have the old school Teves Anti-lock brake system. There is a special bleeding process. Lots of archived info from others.

I suggest starting separate threads for these different problems.


Cheers
DD

 

News on all fronts. Pretty much everything on the dash now works, dirty or broken connections everywhere...the water temp gauge is still dead but I think it has to be the actual gauge or the circuit, as the dash does get signal from the sensor.

As for the tacho it was simply stuck, I poked the small motor behind the speedo and it started working, amazing.

The blowers...well, I started digging into it and as soon as I put a fresh fuse it blows it straight away, meaning that there is a short. I noticed that the nsf blower was stuck, so started dismantling but for some reason there has to be a hidden bolt somewhere as I can't fully remove it from the car...any ideas? I think that the motor for this one is gone, as the wiring looks very dark, so probably burnt.

I also attempted to bleed the brakes and I completely cocked up, now they feel even worse. I think that the abs pump sucked in some air as for a while one of the front calipers was completely dry...any ideas on how to make sure the abs pump is bled?

One step forward and two step back I guess!

Oh also, I gave the clock a continuous 12v feed but although it always gets 12v it only works when the engine is running, so I am guessing that it needs a more direct source of electricity.