XJ40 restoration

Just got my 1988 XJ40 started so now onto the many issues the car has.

Upon starting I got an ABS and Brake pressure low warnings on the VCM.

I will do the checks on the Ebook on the forum. I suspect the pump. I will check the pressures this morning.

Pump tested ok. Destroyed a 200psi gauge but I know the pump is working. All other tests seem to point to the high or low pressure accumulator switch or the accumulator. I may try a gauge testing place and they should E able to place the High and low pressures on each switch so I can test the switches work. I am an Instrument maker (scientific not musical instruments) so that’s how we test gauges.

Here’s a list of what I need to fix on this car that I know of.

Idle speed controller.
Heater tap . Jammed by rust but diaphragm tested ok.
Fuel filler solenoid. Wiring and fuse tested ok.
Drivers electric window slow.
Windscreen cracked
Install factory cruise control from another xj40. Got the bits from a wrecker.

That s all I know of without having driven the car. Auto transmission seems ok on my hoist.

That’s it for today. Waiting for ISC and testing of pressure switches.

Great to hear you now have your car running. Most if not all of the faults in your list are probably due to the long period of standing.
The slow drivers window will probably be just a build up of dirt and crud in the window channels, a good clean and lubrication with a bit of rubber grease should fix it.
Last time I looked the Heater control valve was no longer available but other members have overcome this problem in various ways if you search past posts.
The fuel filler solenoid plunger may be just siezed up with rust/dirt and could possibly be brought back to life with a bit of cleaning if you are lucky.
I would also carfully examine every vacuum hose you can find around the engine for small splits and holes as that will also affect the idle.

Thanks. About the fuel filler solenoid, the pin is free. No rust there. So I am assuming the solenoid itself is seized. I will probably pull the tank and look at the solenoid at the same time.

Thanks for your helpful advice.

Waiting on parts so went about installing the factory Cruise Control items.

I purchased the vacuum motor and dump valve and the car computer panel from he saw car which has the “Cruise Control” (CC) lighting and switching. As the panel with the CC parts was damaged at the wrecking yard I decided to try to remove the “blanking” plate from my Jag and replace it with the CC plate which are held in place with a plastic frame welded in spots to the panel from behind.



I am missing the Throttle actator part to complete the installation. I have been looking on the Internet but cannot seem to locate one.

Brakes update.
Upon reading the Jguar document on the Hydraulic brakes I realise the High and low pressure switches are “Normally closed” type. I will test the rstance of the switches first. If they are open then that switch will be defective. if they both test “Closed / Short” then I will need to have them tested.

Is this the part you need?

There are a couple of sellers on ebay (US) offering them. I had to replace mine two years ago as the bellows was ruptured and I ordered one from a Jaguar dealer in the Kansas City MO area for about thus same price.

I think so. Thank you. Free shipping to the US but I suspect I would pay a lot for P&P to Australia.

While looking at the engine bay I noticed a plug near wher this Vacuum Actuator would sit. I dot thing the Actuator has wires on it. Can you confirm this?
Here is a picture of the plug nera the passenger side firewall on the bottom as shown. I do not now what this is for but I suspect it is not for the Actuator you have shown.

Thanks for the reply.

Brakes update
OOPS. Wrong. One switch is N/C and the other is N/O. They are both correct so i will have to run the car and see if the “Charge” switch comes on. and also the Other switch changes state. It is looking like the Accumulator may be defective.

CC Update.
Installed Vacuum motor and plugged everything in.
Checked the Fuse in the centre console.
Put car in “D” with ignition On and 'NO RED LIGHT" on controler.
I suspect the ECU behind the glove box is not the one for the CC option as i thought.
Tommorow I will swap it for the one I removed from the donor car. I have checked that the vacuum motor and the relay all work. The only thing it could be other than a wiring issue which dows not seem likely.
Fingers crossed.

The actuator has no wires. A vacuum line connects to the black nipple. The adjacent gray threaded stud is how it connects to the mounting bracket.

Thanks for confirming my suspicions Mike.

I will wait to see if any forum members know what the plug is for.

I am learning a lot about this Jag. I thought the big box with all the wires going into it under the glove box was the CC MODULE. Not so. It is an aluminium box with two spade type sockets. I found the connector s hanging down near the box I mentioned above. No wonder I cannot get the red light to work. I need to get the module and the actuator. I also may need the CC INHIBIT switch next to the brake switch.

Removed Accumulator and gently pushed a bit of wire into the Accumulator and no rubber. The wires went clean through to the steel end. I need another one. The two pressure switches are not leaking and they are electrically ok. I will risk putting them back in.

I still would like to verify that the green reservoir hoser are routed correctly. Any help would be appreciated.


Thanks 2tonejag Two different size hoses on The green plastic HSMO (Hydraulic System Mineral Oil) reservoir - #7 by 2tonejag . I can rest easy knowing that the hoses are correct.

I just checked the front rotor minimum thickness embossed on the disc (24.9mm). I measured mine at 20.5mm. I cannot believe it has been machined so thin.

New discs and drums all round . I already ordered the pads and shoes. i will need to look at the brake pistons and cylinders also. Next job.

While waiting for parts to arrive I tested that Sony Head Unit that came with the car. i noticed that when I tried to get the sound out of one speaker only with the Balance and Fader controls (ie Left rear only) I got sound also from the other speaker on that side. So after some invesigation I realised that the PO had used the existing wiring (but the ground was isolated). After some testing and viewing the Schematic from tha Haynes Manual I could see why.
The pictures below explain why I did what I did.
XJ6 Speaker common isolation process.pdf (68.4 KB)

So I removed each front door card. Cut the Red/Green wire going to SP Neg ( Just hangs there with no connection). Connected a new piece of wire to the speaker Neg and ran it to the Radio unit. I then cut the radio Front Left and Right Neg going to the Speaker connector shown below and reconnect the radio wire to the new wire I just ran. So the existing wires on the speaker connector below are also going nowhere.

Now the radio balance and Fader controls work as they should. with these controls I can make the sound come out from only one of the 4 main speakers.

This is a test to check if your radio is wired correctly.

Speaker side radio connector.

CC Update.
I tested for the Brake light signal at the CC module connector and for some reason I can see the brake signal even though I only have one swith at the pedal end. So it should work when i get the module.

The CC red light was blown. It is actually a LED. I replaced it and all is fine so far. I need to test it out when I can run the car.

Under the drivers seat I found a BLAUPUNKT 2 channel power amplifier. I reinstated the blown fuse but it blew also. I replaced it and now I have the amp powering the 2 rear seat speakers.

Getting there.

I noticed the wiper arm was worn and not gripping the motor spindle but after testing I noticed the spindle was not stopping (Parking) at the same spot but intermittently. I suspected the microswitch but testing revealed it was working. After reading some posts about it I suspected the Elecronic module but upon testing it I noticed the microswitch signals (both park and go) would sometimes dissapear which made me suspect the module. But as the module was expensive and from England I thought I would try a new micro switch. This cured the issue. Upon further testing I noticed the resistance on the NC connections were changing if I moved the termminal.

Now to Pin the wiper arm onto the spindle and that should be it for the wipers.