Hey everyone, I hope you all had a great holiday.

I got my present early, my 99 XJR does not start I had an earlier problem with it, where it would hesitate when I hit a pothole. I could start it just fine though. It did it at random times, and has not done it for over 6 months. About a month ago I had a problem starting it, it took me a couple of tries but it was fine the next day.

On Friday the hesitation when I went over pot holes came back, and I had a hard time starting it. Saturday I got in my car turned the key and nothing....

It keeps just cranking. I had it towed to a my mechanic. I tried starting it a dozen times.... The battery is good, the fuel pump(tested) and it works. It would give me a random "Traction Control Failure"(don't remember the exact wording), as I was trying to start it.

The mechanic is getting Code 1797. Any idea why it will not start at all, or how to pinpoint the problem? I have been looking online and in the forum and cannot find that much info.

Any help will be much appreciated.
Thanks,
Victor

When fault is detected:
– TCM adopts transmission
mechanical limp home mode
(4th gear)

– ECM limits engine power
Other CAN control module CAN related
fault(s)
CAN open circuit fault – ECM to TCM
CAN short circuit fault
ECM failure
TCM failure

 

I did look at this post

https://www.jaguarforums.com/forum/x...-1797-a-28514/

but it does not say if the problem was fixed or not? Or if the ABS circuit board was at fault at all.

 

An ABS code should have nothing to do with an engine start failure.

If the tech telling you anything else?

A bump related miss sounds like an electrical problem. Check all the connectors you can find. Reseat or swap the ECM relay.

 

Victor:
I will say that my XJR does a engine power reduction over a bump as part of the traction control strategy. As testpoint said, that should have nothing to do with no-start. I beleive you have two non related issues here.

It sure seems youi have the correct P1797 diagnostic. I checked Alldata and JTIS. I don't know where the "Neutral Switch " might have come from, but i doubt it is an accurate Jaguar source. And the nuetral switch will cause a no crank, not a no start.

If you might have started it and run for a very short time last time you started it, or even if not, you should consider the chance that you have a cylinder wash. There have been several good posts recently about this, or chack the archives or Gus;es site.

 

Thank you for the feedback.

The mechanic told me that all the plugs had a weak spark.

He sprayed cleaner in the MAF i believe in the begining and it still would not start. He removed and heated the ECM a bit, thinking there might be water in it. After he reinstalled it, the car started. He tried it a few time, it worked fine. Tried one more time would not start again.

 

A bump in the road can cause many things including dislodging a relay, connector or fuse. If the car is not starting with the shifter in “P” then move it to “N” and try it again. Be sure you have fuel and spark! As for your P1797 code when did that come up? If it was well after the no start it could be caused by a low battery that was caused by you trying to start the car. If you have spark and fuel then you might have a cylinder washing issue and I recommend that you read this Jaguar Nikasil Engine Blocks & Jaguar Nikasil & Sulfur If you think you have a cylinder washing issue then read this Nikasil No Start Cylinder Washing When you do the starting procedure be sure to have a fully charged battery, it will not start right away.
This is for the codes http://www.jagrepair.com/images/Auto...tem%201999.pdf

 

Hi everyone, I wanted to update you on how the problem was fixed. The mechanic changed the fuel pumps and it starts every time now. Apparently one of them was shorting out and the other one was not in great shape.

However I still have the hesitation, or almost stalling feeling when I go over bumps(no pattern, does it randomly)

Thank you for all your help

 

I'm beginning to get this myself. Any resolve as to what it was for your car? Sometimes, after hitting bumps, it will hang around for a while (occasional hesitation/stalling), but sometimes it goes right away after the bump. One thing I notice is that if I unplug and replug the TPS connector, it goes away. Sometimes for a day, and sometimes for weeks. I've cleaned the connections, and even coated both sides with Silver Contact compound, but same thing happens. I also notice it happens when at partial open throttle (Low). Could it be that the TPS is failing internally? Why would unplugging and replugging help?

Any thoughts or ideas would be welcomed.

 

Heres the problem . Hooked up a AUTEL SCANNER 509s yesteday just rec'd .
The shifter locked up could not get out of park so shifted to J box then started and went back to regular.
No codes found other than P171/P174 the day before.
Now pulling both P1642 and P1797 > Could the scanner have caused this instant effect .Also have Garmin attached via cig lighter . noticed that mentioned in previous thread. Seems I'm worse off than before I scanned>
Any thoughts?