I read over the mentioned thread (it's pretty lenghty) and what I took with me is that a Ford FDS2000 will also do the job because it has the same design and hardware as the JDS, just the software is different and that is loaded from CD. In case the CD-Drive doesn't work anymore there is a way to exchange it against an IDE device. I found some FDS2000 offered around here but I have no idea if they are complete or at least contain all components that I would need. Gotta dive in a little deeper.

 

I read through the transmission manual and the diagnostic codes and there are only 4 codes that would actually comply with the situation/symptoms that I encounter. All other codes will either be detected when the car is not moving or they will cause limp home mode (e.g. any TCC related code).

Three of them are related to engine or input speed signal. #68 would be the closest one related to my observations.

 

Hi,

I am having trouble with the transmission on my '93 XJ12 and I am looking for a way to read the error codes. From what I have read here it is fairly easy to use a Ford FDS2000 with the JDS software. But at the moment I am struggling with a more basic issue, I can't get that cap off the diagnosis port in the trunk. Is there a trick? I tried to pull it, push it, turn it, but it doesn't come off either way. The outer ring can be turned for just a few degrees and it looks like its coming out thereby but then it stops. Are they known to get seized or is there something have to do I haven't found out yet?

Thanks,
Oliver

 

I have seen your post in the PDU thread and I am wondering where in Germany you are located. There are several FDS2000 units in working order in Germany and maybe one closer to you then you know.

 

I can't help with the connector, but there is an alternate way to get transmission codes assuming your car has the GM 4L80 transmission. Locate the TCU. There are a couple (maybe three) connectors on it. Find connector "A". On the vehicle side, pin A8 is unpopulated. Run a wire to that pin on the TCU. Turn the ignition to on, but don't start the car. Briefly short the wire from A8 to ground. The transmission warning light in the cluster will start flashing. It will always start with one short flash then 2 short flashes, code 12. It will then start flashing other codes with a longer pause in between codes. Eventually it will cycle back around to code 12, then start showing the other codes. It will continue doing that until the ignition is switched off. A list of codes is attached.

On my 95 XJS, I ran a wire fom A8 along with a ground wire to my console and added a button so I can read codes anytime I need to. The TCU is hard to access on the XJS coupe, so this was the easiest way. It's helped me find a bad solenoid in my tranny.
Yes, a working PDU with the Jag software will read the codes directly. You will need the correct vehicle cable, as well as the VBA power supply hooked to the PDU when you read the codes. The PDU base station is required to read the CD data into the PDU for each system you want to test.

 

With TCU you mean the transmission control module also referred to as TCM? Would be great if I could read the codes just like this. My latest information is that the TCM should be located in the trunk, but I haven't looked thoroughly yet, at least I couldn't find it behind the dash.

 

I am from the Southwest of Germany also known as 'Rhein-Main-Gebiet'. Do you know anybody from around here with a working FDS2000?

Anyway the hint given in the PDU thread might already solve my issue, if I manage to locate the TCM I should hopefully be able to run a wire from A8 to ground and simply flash the codes.

 

On the LHD 94MY XJ40 (ZF transmission) the module (Bosch) is located on the passenger side, fitted horizontally, low down next to the engine ECU. Don't know if that applies to your 12 though ...

 

I know a company who have a FDS2000 but are Ford minded in "Plaidt". They probably doesn't have the correct cable and software for your car but we can fix that (not sure if they are willing to take a Jag in). Other option I might have is in Ludwigsburg, there is a Jaguar minded person with a working PDU and I assume the correct cable. So if you are interested in one of them let me know I will then contact him and ask if I can forward his contact details.

Personally never tried the blinking procedure but have heard of it.

 

And to open the cover you have to turn the outer ring. Best picture I have with the cap of you see here.

 

And here is an interesting thread:
https://forums.jag-lovers.com/t/xj-s...-help/341509/3

 

Yes. Meant to say TCM.
I don't know XJ series that well, but your car being a 93, I assume it's the X300 body style. From what info I have, it should be under the dash on the right hand side (passengers, assuming a LHD vehicle).

 

I see ... so that outer ring belongs to the cap. I wasn't quite sure about that, but I assumed it needs to be turned as it was the only thing that moved at least a little bit. Does it open anti-clockwise or clockwise? Probably will need some pliers as mine seems to be stuck.

As end of October is approaching, I will probably not be able to go anywhere further with the car in order to have the codes read. But of course it won't do any bad if I had some contacts in case I am not able fix the issue myself over winter.

 

Thanks for that link as well! It does not only describe how to flash the error codes, the guy that started it possibly had the very same issue as I have. I think according to my observations a bad speed input sensor is a hot candidate and seems to be a common issue. My current second guess would be the engine speed signal that comes from the ECM. Does anybody know where this comes from? Is it derived from the ignition timing or maybe coming from the crankshaft position sensor?

 

The 93 XJ40 has an upgrade which occurred in mid 92. It still has the earlier body, but the electrics are quite different and similar to the X300..
The easy way to pick the upgrade is the battery went from the engine bay in the early cars into the boot (trunk) in later cars.
The XJ40continued in production until mid 94 when it was superseded by the X300.
I had a 94 XJ40 and it was a pain in the butt as the XJ40 workshop manuals related to the earlier pre 92 cars.
I remember it took me hours to find the fan relay which had failed.
From memory I think jal1234 is correct in the location of the access point

 

I already had a look behind the passenger side dash but just found a bunch of other control modules (light, comfort functions etc.). But I know the ECM must be somewhere there as I was already connecting some vacuum lines to it that came through the firewall, but I don't remember exactly. Must be somewhere behind the other control modules I guess.

 

As I mentioned in an earlier post, on my car it is mounted horizontally at the very bottom of the passenger side dash. IIRC it's in front (nearer the firewall) of the Engine ECU. Remove the air duct (swings out from the right) to give you a clearer view of the components at the bottom of the aperture.

 

Hi V12Lover,

On our '93 six-cylinder XJ40, the TCM was item number 9 in the photo below:





For identification of the other modules in the photo, see this link:

The Brains Behind the Dash

Cheers,

Don

 

#1 through #5 look pretty much the same on mine. And I also have seen #6 but rather vertically mounted than horizontally. Is there a tray than can be loosened so all the lower modules fold down?

 

Got it! It's in the trunk on the right hand side behind the liner. It looks exactly like this one. But I wonder where connector A8 is now. There is this violet double connector but no free port. I would need to disconnect it in order to access the pins. But how should it communicate then with the car any longer?

Got it, it's two connectors, one named A and one named C. So I have to unplug Connector A and the connect the wire to pin A8. Stupid question: is A8 a single pin or does the pin below belong to it as it doesn't have its own numbering?