I guess I will just have to junk the car looks like I can not get a cross what problem I am having in writing. I have did the best that I can in explaining what the shop and I both see. All I can say it wont pass NYS inspection. there are no signs of a problem when the car is driven, when the scanner is hooked up all the tests fail. when I try a scan all the test fail and then the scanner show a P1797. thank you for your help but guess its time the junk yard. its a shame but no other option. thanks again George

 

George, Please understand "we are trying to help". Sometimes in writing it will sound like a sarcastic remark, believe me, it's not the case.
If you still are willing to give it a try, the folks here will solve it, but we can only send you in the right direction, not being in your location makes it more difficult.
There is a plug on the side of the transmission, this gives some problems with communications to the ECM. It is a turn and pull with lots of small needle type connections. Get it loose and spray with electric connection cleaner on both sides. Let it dry and do a hard reset. If this is the problem, wonderful, if not, lets see what else is driving us nuts.
How much time do you have to correct the problem?

Wayne

 

That seems rather extreme. If you can't DIY what seems to be an unusual problem, then possibly there's a good Jag mechanic in your area.

One noticeable thing here:

means you actually made things worse by resetting the entire system to 'zero'. That's why your scanner now shows all 'tests fail'. It takes several hundred miles (possibly a thousand miles) of normal driving to reset all the monitors so that they show a pass. This is normal. The distance driven can be reduced substantially by following a specific driving procedure that's available here.

I asked the following question

but got no answer.

Again, people are trying to help.

 

As above - we're trying to help !!

For over two years, I had a P1797 code BUT I also had an EML light and the car sometimes went into "limp mode".
I eventually disconnected, cleaned, and re-connected EVERY connector on the CAN (computer network) that connects all the various modules together. It's nothing complicated - just a pair of Green and Yellow wires twisted together.
That seems to have cured the problem - no faults for over six months now. I suspect - but can't be certain - that it was the connector on the instrument pack that was causing the problem - these cars are "hyper-sensitive" to voltage and a small drop is enough to freak-out the computers. In view off the fact that the battery was flat for some time, and may therefore be damaged, I would risk the investment in a new battery. I would also drive the car a considerable distance over a decent period of time to get all the various monitors settled down as Mikey very wisely suggests.
You do not need to junk your car - it's something fairly small and simple, but it will take time, and maybe the services of someone with the proper Jaguar diagnostic kit, to make an accurate diagnosis.

 

getting no other errors just the 1797

 

i would drive the car but it failed the NYS inspection so the car has not inspection sticker so I am out of luck on that. Thank you for all your help. George

 

Any 1997 US market car that does not communicate well through the OBD plug makes me suspect that the problem is in the ECU itself. Sending it to ASI for testing is not expensive and will at least ensure that the ECU is okay.

http://www.autoecu.com/

 

Are you not aware of this?

https://dmv.ny.gov/brochure/what-do-...cars-not-ready

 

Mike yes I know about the ten day extension I am way passed the 10 days and you only get the 10 days once. Not sure how to get to drive the car to make the car ready. Thank you for your reply

 

Can you expand on this - what tests fail? What exactly does the scanner report before the P1797?

Mike

 

Mike. here is what happened. I put the car away in late Oct. of 16 there we no errors that I know of at that time. No red lights and no error code displayed. I forgot to put the battery maintainer on, a few months later I went to start the car battery was dead. Look like the trunk did not close correctly and the trunk lights killed the battery. I charged the battery check the cells all looked good. I started the car on Jan. 17th. started right up ran for 15 mins. no errors lights or codes at that time. Put the battery maintainer back on closed the trunk and left the car until the first week of May 17. I stared the car no red light or errors, I drove the car around for about 150 miles then took it in for the NYS inspection It failed the shop asked if the battery was out for the winter and told the it went dead they thought I had not driven it long enough. They failed the car and gave me a 10 day extension so I could get more miles on so I did another 100 or so miles. I went back to get it reinspected before they hooked it up to the NYS computer they tried a OBDII scanner it failed with no connection so they tried 3 more scanners same problem. They then hooked it up to a snap-on tester it also failed then posted a P1797 error. I have a Launch CPR129 scanner that did work on the car when I got it but never needed to use it., I plug it in it runs a bunch of tests they all fail then it post a comment and asked to make sure it is plug in correctly and the the car is OFF and to make sure the car is a OBDII car. It was plugged in correctly,the car was OFF, and it is a OBDII car. I run a manual scan on the TSM and it fails with a code of P1797. It fails on any test I try with P1797. That is where I am now. No other errors show up. If you have any ideas Please let me know Thank you and all the guys on the forum for they help...George

 

OK
Sounds like your inspection procedure puts you in a Catch-22 situation. Can the car now not be driven legally at all unless it's to/from a test? Heaven save us from misguided bureaucracy...

I would not give up and junk the car - especially if it has served you well and has no major issues. It's entirely possible that this is a trivial fault. Folks on here will guide you as best they can (and there's some pretty heavyweight knowledge amongst the members) but it may take some time to pin down, and you may be asked for clarification.

Observations:
1) It's odd that you're not getting a MIL (check engine) light on the dash. P1797 is a '2-trip' fault that would normally cause a MIL the second time it was thrown (see GGG's previous post).

2) Any battery that has laid in a fully discharged condition for a period of time should be treated as suspect, IMO.

Do I understand you correctly that only one scanner reports the P1797, and all of the others fail with a 'cannot communicate', 'ensure that the plug is in correctly' or similar errors?

Mike

 

Mike That is my problem The car can not be driven even to the inspection but that is not a problem he is only 5 mins away I can get it there. My only chance is to drive it at night which I will do when I go back up this weekend. Not sure how long it needs to be driven? There are no lights or errors at all on the dash. Mike my scanner and the big Snap- On one show the 1797 only after you do a manual scan. If you Just plug the scanner in it tries to connect and then says no connection thinks it is not plugged in??? and ask you to make sure the car is off and the plug in in correctly. I had the battery check by Exide battery company they are in the next town in CT and they say it looks great. Love the car hope we can get it fixed. Thanks Again George

 

Hi George,

You have stated more than once that you are using the scanners when the "car is off." By "off," do you mean the engine is not running, or the key is in the OFF position? Most modern scanners will work whether the engine is running or not, but they all require the key to be in the ON position (position II) to power the circuits required for communicating with the electronic modules via the OBDII data link connector (DLC). Are you using your scanner with the key in position II?

Graham posted the relevant information from the DTC Summaries guide in post 6, which gives some possible causes of P1797. Since failure of the Engine Control Module (ECM) or Transmission Control Module (TCM) is far less likely than a wiring problem, the first thing I would do is disconnect the battery negative cable and clean the electrical connectors at the ECM and TCM with zero-residue electrical contact cleaner spray and a small wire brush.

If P1797 recurs after cleaning the module connectors, inspect the Yellow and Green CAN harness wires between the ECM and TCM. Disconnect the ECM and TCM and check the wires for continuity and isolation from ground. If you have no continuity on one of the wires, it is broken somewhere. Flex the wires while testing continuity to find an intermittent break. If either wire has continuity to ground, it is shorted somewhere.

The CAN wiring schematic is shown on Figure 19.1 of the Electrical Guide, which you can download here:

Jaguar X100 Electrical Guide

Cheers,

Don

 

 

David thank you for you info on the diagrams. To answer your question yes the key was in position II. I got the diagram and will be working on the car this week and hope I can find the problem. Thanks Again. George

 

Thanks for the diagram. will check as soon as I can

 

George,

If you drive normally for long enough and far enough, the OnBoard Monitoring Tests eventually complete. However it can take hundreds of miles and a much quicker method is to deliberately do 'drive cycles'. Here is the 'drive' cycle' sequence for each of the 6 diagnostic monitors:

OBD DIAGNOSTIC MONITORS.pdf

It's the driving sequences which are important. You can ignore references to checking with 'IDS' which is the old Dealer scantool.

After reading through the thread again, I still suspect the BATTERY despite it being given a clean bill of health.

Graham

 

Answered above in post 23............

 

NO - you MENTIONED it in post #23. I ANSWERED it in post #38.

Graham