P1797/1799 Codes
 

I'm getting P1797 and P1799 codes on my OBD2. From the threads I've read on here those codes seem to indicate a short somewhere in the wiring (https://www.jaguarforum.com/threads/...e-p1797.73330/). Anyone know if this code would cause my monitors not to reset? I'm having an issue with the CAT and CCM monitors reading INC. I've driven all the different "drive cycles" I've found that were supposed to reset these monitors with no luck. I've replaced the downstream sensors and put in a new battery. Would the issue with this wiring cause the monitors not to reset?

What gearbox?


https://cimg4.ibsrv.net/gimg/www.jag...d20a10da76.jpg

Whatever one they put in the car when it was built. ZF5HP24 from what I understand. It’s a 2001 XK8.

Recommend adding Model and year to your signature as if you don't include that information in your posts, one can look at the signature and better be able to assist based on specific know configurations for a particular year. To add a signature, click the little down arrow next to your user ID in the upper right corner, click User Control Panel, then scroll down to edit signature

Hi Joe,

On the ZF 5HP24, P1797 and P1799 indicate a loss of CAN communication between the transmission control module and the Engine Control Module. One common and likely cause of codes like these is oil contamination of the electrical connector on the transmission itself. Another is corrosion on the electrical connectors at the ECM or TCM. Problems with the internal wiring harness in the transmission are known, and failure of the TCM is also known. Good salvaged replacement TCMs are available on ebay. Look for one with the exact part number and VCATS version as yours and no programming should be required.

Check the electrical connector at the transmission first, by disconnecting it and inspecting the pins in both halves. Oil residue indicates the O-rings on the electrical connector sealing sleeve have failed and are allowing transmission fluid to contaminate the connector.

The Workshop Manual gives Pinpoint tests for diagnosing these types of codes. If you don't have the manual pdf, I'll try to find the link for you.

Cheers,

Don

Hi Don,

Thank you for the info. I'll won't have a chance to get back under the car until Tuesday, too much to do today and we babysit 3 grandkids (all under 2) on Monday. I'll definitely give that a check and see what is there. I thought I had the workshop manual but I'm not finding it.

Would this fault be causing the CAT and Component monitors to fail to reset? I've put in a new battery and replaced the downstream O2 sensors. I've tried the various "drive cycles" that I've found on here and other sites but thus far both of those monitors are still reading INC.

Joe

done.

Sadly doesn't seem to be working.

After you add your vehicle information in Edit Signature, you have to scroll down and click Save Signature.

I do have the Workshop Manual in pdf format but it is 75 MB and the forum only allows uploads smaller than 20 MB. Some of what you need may be here:

https://www.dropbox.com/scl/fo/8zl7r...94bjdeka6q&e=1

or here:

https://www.onlymanuals.com/jaguar/x..._40l_aj27_1999

Cheers,

Don

No, those have nothing to do with the CAT monitor. Remember when you posted the low voltage readings of your one downstream O2 sensor? That's the most likely culprit. If you're still getting low or highly variable readings then the cat is most likely shot. Welcome to the club.