I have just been told by my local Jag dealer that no one on Vancouver Island has a working diagnostic code reader for my '92 XJS v-12.

Can anyone tell me which code reader I need to start searching for.

 

Steve,

You need to find a Jaguar PDU system (which will be extremely difficult!). Jaguar used a bespoke protocol system on their pre-OBDII compliant cars.

The best thing to do is to get a trip computer for your car (if not already fitted) which can display the engine fault codes.

Paul

 

I would guess then that you are not referring to the stock trip computer that came with the car?

 

Steve,

Yes,that's the one.

Paul

 

On '92 and up XJS', the trip computer is used to display fault codes. Turn the engine off, and wait 5 seconds. Turn the ignition on, but don't start the engine. Any fault codes should show up in the trip computer display. You have to fix whatever causes the first code, and then it will display any second code, and so forth. You'll have to look up whatever the displayed code(s) means. Very rudimentary.

Whether this made it to all early 92's, I don't know. I got this info from reading the various forums, as I don't own an XJS that late.

 

The same principle also applies to the trip computer in pre-facelift cars - ie those before April 1991.

Paul

 

I have a 92 XJS convertible. The fault codes are suppose to come up on the trip computer like said above. Mine used to but now I get a check engine light but no code. The owners manual that came with the car has a list of codes. It also says if you have a check engine light and no code the ECU is faulty. I will have to deal with that at some time.

 

catterwaller,

Just try a hard cleardown of any codes and see if the light (and code) comes back.

Paul

 

Maybe silly question.
My facelift 94 XJS (has the AJ6 4.0 engine) has the clock on the dashboard instead of the "computer" screen.
Is the computer there anyway and so do the codes eventually appear instead of the km indications?

 

Serge,

No, the codes only come up on the trip computer screen. The good news is that you could plug in a trip computer in place of the clock.and just change the veneer surround.

Paul

 

By hard cleardown do you mean disconnect battery for a few minutes? If so I've done that. Anything else?

 

If you don't want to remove the clock permanently you could plug in the trip computer for diagnostic purposes and replace clock when done.

 

Not sure that would be worth.
I would first need purchasing a trip computer from e.g. Jaguar Classic Parts:
Ordinateur De Parcours Et Interrupteurs De Tableau - Pièces Pour XJS de (V)179737 a (V)226645 | Jaguar Classic Parts FR
then dismounting the clock and verifying that I can easily connect the trip computer on the existing wiring behind the dash (hoping that the cables for the computer are there), then extracting the DTCs and finally reinstalling the clock...
I would prefer plugging a modern codes reader, but issue is that the car's diagnostic connection is OBD1 and ...in the boot (not OBD2, which is only available on AJ16 cars)

 

caterwaller,

If that doesn't work, try this:

Behind the cheek panel on the front end of the transmission tunnel there's a yellow wire (+trace colour) with a purple connector on the end. Can't remember if it's passenger or driver side. It's by the heater fan electrics. Turn on ignition, put a wire into the terminal connector and then earth the other end. This clears the fault code. It may also clear your MIL.

Good luck

Paul

 

Not as much trouble as it seems. The clock is held in by pressure. Popping it out is simple. The connections for the trip computer are back there, so swapping out the clock for the trip computer and back again really takes minimal time.

When you're done, just push the clock back in, and voila! You're done.

It's basically a $200ish obd reader, trouble is finding one. eBay is a good place to look.

 

I have 2 trip computers for preface lift if you need one. I'm not sure if they are the same.

 

Unfortunately, facelift trip computers are quite different.

Paul