Here is a diagnostic tip for the 1995 X300 VDP with traction control.

Having spent considerable amounts of time trying to diagnose a cruise issue (check out some of my previous posts) which I have yet to get straightened out. I have given quite a bit of time to ancillary systems and the limitations of being able to read codes and data. So thinking to my self..

"Jaguar cannot be by themselves with this ABS/Traction system. Some one else has to be using it"

My first guess was it had to be Ford (since they owned Jaguar at the time) and what better than for it to be a LINCOLN Town Car of the same vintage. A bit of research confirmed my suspicion that indeed Ford did use the same system. Now all I had to do was some research on the TEVES MK4 system and the 1995 Jaguar diagnostic connector for common areas. Well it turns out both Ford/Lincoln and Jaguar not only communicated on the same OBD2 diagnostic terminal (pin 7) but also on the same terminal of the ABS module and both marquis's used single wire "K" line data. Next up was for me to make sure my scanner (Snap On Modis Ultra) would make the handshake on pin 7 only. So I broke out my OBD2 break out box, powered it up and connected my scanner to it. Using the 1995 Lincoln TC ABS diagnostic I attempted to communicate with my break out box. On the first attempt it signals on multiple terminals, but on the second attempt it only does so on OBD2 pin 7. On the 3rd attempt it does multiple terminals and on the 4th attempt OBD2 pin 7. SO with this information in hand I decided to give it a go on the Jaguar. Keep in mind that the AJ16 engine also communicates on OBD2 pin 7 so I was a bit apprehensive.

Over the last 2 days I had addressed a few issues I found, such as the lack of insulation on the motor leads for the traction control motor ( I found previous posts concerning the insulation crumbling) I insulated those motor leads. Also several comments about throttle cable adjustment and of course the broken secondary throttle cable at the TC servo. Also another thing I had noted was an issue I had when lifting the vehicle on my hoist and after lowering it I always got the ABS/TRAC fail and Trac Disabled lights on the first test drive. I know from experience that often ABS systems do a pump motor test above a certain speed on the first key cycle. Typically you will notice a momentary drop in system voltage ad the pump motor operates. This was something in the back of my mind I had not experienced on the Jaguar and was a bit suspicious.

So tonight, after taking a road test I attached my scanner loaded with the 1995 Lincoln TC ABS test and went for memory codes.....





Well I was quite pleased that Immediate results posted!!

I did attempt to erase those codes but either they failed to erase because of incompatible communication or they are in fact active codes. Also I was not able to do a KOEO test due to "Incorrect condition" So my next plan of attack is to delve further into the parameters of those codes and testing.

 

I recommend using a scanner that does not need to be connected to the car before you select the year/make/model and system you desire to test. It is common that if you do the scanner will start to send data requests out on various data lines, some of which may have disastrous results. You have been warned!

 

Going back to my original post using a Snap On scanner configured for a 1995 Lincoln Town Car I was unable to read data nor perform the KOEO Test (Key On Engine Off). I was able to do the Code Clearing Procedure but when checking for memory codes they were still there. However There are 2 other tests that can be performed if there are no active codes. One is the Pump Motor Test and the other is the Automated Bleed Test. Although either if these 2 tests can be performed with the KOEO or KOER (Key On Engine Running) I recommend doing them whilst the engine is running as they can take a few minutes to perform. During either test the pump motor will be running and since it is a high power draw device it would be in your best interest to make sure the battery does not go below minimum voltage.

As a confirmation of my repairs, I disconnected the ABS module connector for 10 minutes. Upon reattaching same I performed 2 key drive cycles (switch engine on, perform test drive above 30 MPH, stop, place in reverse on slippery surface and apply enough throttle to cause the ABS and Traction Control Throttle Actuator to operate, then switch engine off, remove key, open and close driver door, wait 2 minutes and repeat) On the second drive cycle, do not switch the engine off and perform the Pump Test and Auto Bleed Test. If there are no active codes these tests will be enabled and you will have confirmed all is well.