A check engine light came up on my '01 XKR with 83k miles. I read the OBD II codes as P1797 - CAN TCM/ECM Circuit Malfunction. The car had just been driven on the highway and sat in a parking lot for 2 hours before I tried to start the car. I received several warnings parking brake, Traction Control. ABS, and the car would not start. The engine would not even turn over and a warning of Limp Mode appeared. After several more attempts the car started and ran fine with just the check engine light on. After reading the code, the check engine light was reset and has not reappeared.

After searching for other threads about this same code, I am going to do the following:
1, Check battery for low voltage, 12.1 or below. Replace if low voltage. The battery appears to be Jaguar White in color, just not sure when it was replaced.
2. Check all connector to ECM/TCM, clean.

Has anyone else experienced this code and do you have any other suggestions? I am driving this weekend to a Concour and do not want to get stuck in a parking lot.

 

if you got 9 years out of your original OEM battery, that is fantastic! Definitely sounds like a battery issue, get it tested, but I would wager my lunch that is the problem.

 

I had the battery tested and the battery checked out fine. It was rated 12.64 volts with 914 CCA.

The battery is from Jaguar based on the label but no indication of date of installation. The Model No. is something like 65-68BH??

It seemed odd the battery was from Jaguar but no vent was visible and the vent hose was not attached.

I'm going to wait and see how the car runs now as it is running perfectly.

Should I be concerned that this same problem could occur again, or do I just blame the electrical gremlins?

 

Just part of the enjoyment of owning a British automobile! You should have tried a '70's MGB.

 

I have noticied that the battery seems to sweat and is leaving a powder residue on the floor of the boot. Even though it is the original Jaguar battery I am unable to locate the vent hole on the battery to connect the vent hose to. I had topped off the battery fluid in the fall with distilled water, perhaps I overfilled? What could be causing the corrison at the bottom of the battery. Is now the time to change to a new battery? I am going to detail the battery compartment and will consider replacing the battery at that time.

 

if you need a pic of the battery area from one of our cars, let us know. We can show you the proper vent tube location as well.

 

Just change the battery they are like $80 at Kragen/Autozone battery technology has come along way since 2001. My 2001 XKR battery died back in 2006 at 38K miles so dont trust them when they are that old. Also had elec problem just b4 it died windows, restricted performance e.t.c e..t.c

 

I agree with you simonnallen, I am planning on replacing the battery with an Interstate MTP 93, 1000 amps and 850 CCA. I called the website today and Customer Service told me that this is the same battery dealers use to replace the original Jaguar installed battery at a fraction of the price. After I install the new battery are their other memory settings besides radio, windows and seats that will have to be reset?

 

I thought about that one also, but pricey. I chose the Duralast Gold from Autzone instead, and pocketed $100.

 

This same code plagued me for several months. It just came up out of the blue one day, and I was lucky I was only about 2 miles from home. I had slightly different symptoms, though; the most annoying of which was that the engine would only run after a cold start, and for only about 12 seconds. It would then stall, and all sorts of weird messages would pop up, like gearbox failure, ABS/Stability failure, and engine not charging; but the strangest one was the parking brake light would blink randomly, without the parking brake being set, and the light on the cruise control button would blink randomly, too.

I checked all the CAN circuits & connections, and they were all ok. I learned here from reading this forum that most code readers do not read the codes stored in the other modules like the TCM or ABS modules. So I went to talk to an indy Jag mechanic to see if he had the equipment to read the other module codes, which he did, and would charge me about $125 to read them. Plus, I would have to tow the car to him for this service. Yikes! He asked me why & what was going on, and after I told him all of the above info, he told me to try and re-start if after it stalls, use the accellerator if necessary, just do whatever to try and get it running after it stalls. Low and behold, I was able to do this, but the engine ran wildly, surging up to 3 grand on the tach, and then back to about 1 grand in a rythmic fashion. The temp & oil guage readings would also jump up & down in sync with the surging (all these guages get their info from the CAN buss so it sortta makes sense). After a few minutes of that, and not seeing any benefit to how crazy it was running, I shut her down and resigned myself to drag it into the indy mechanic for analysis.

The next day, just for s--ts & giggles, I tried another 'cold' start. To my utter amazement, it ran perfectly and has not given me anymore trouble since! I credit the repair to God and tell everyone "He fixed my car!" I have no better explanation.

As for the battery, I, too, have the Duralast from AutoZone. (It's a little shorter than the Jag battery, so I cut a piece of plywood to place underneath it so the hold-down bracket woud work correctly.) It was only 9 nine months old at the time of this problem and I also kept a trickle charger on it because the car was not driveable. Now, the battery is about 18 months old, and no more troubles, so, at least in my case, I don't believe it was the battery. Like I said, God fixed my Jag!

 

Did you ever get to the bottom of the p1797 faults...mine has very simular symptoms!