XK8 fault codes P1797 P1798 P1799
My car has been in my garage at my house in Florida for two years untouched. We have not been able to go to Florida as Brits are banned from travelling there at the moment. We are in process of selling our house there (can't use it!) and my wife managed to go to a different country that wasn't banned for 14 days and was able to get in.
So, now the problem.............She charged battery which was low and car started fine. She used a couple of times over the next few days and no problems. She went food shopping yesterday and phoned me in UK to say it sounds like it was only running on four cylinders. She arranged to get it taken to a local garage who put OBD on it and said code P1797 P1798 P1799 were coming up. He said he doesn't have time to look at it right now and is retiring in a month so not sure he will get round to doing anything!! Basically he doesn't care!
So now i have to find another garage and decent ones are few and far between in Clermont Florida.
Can anyone shed light for me or have experience dealing with these codes, is there any simple tests that can be done, my wife has VERY basic knowledge of mechanics.Is there any go to possibilities that she could try? Perhaps you experts on here who helped me massively before could offer advice.
Many thanks in advance
Phil

 

I phoned tons of garages, import specialists in my area and none want to know so I guess I am going to have to get it trailered to Jaguar Main Dealer next week.
Is there nobody here who can tell me if there are things i could look for that might be obvious?
Phil

 

Phil,

Knowing the MODEL YEAR could be more helpful than the vehicle's precise LOCATION.

The codes are transmission related and fortunately have similar possible causes across the years. Here's the Jaguar decode for 1999MY:




The "sounds like it was only running on four cylinders" is indicative of transmission limp home mode.

An Independent is going to be expensive to troubleshoot and fix this. A dealer, even if they would touch a model that's been out of production for sixteen years, would be astronomical in labour charges alone and probably get nowhere.

As it's been sitting for two years and was presumably OK when you garaged it, my first thoughts are to put a new (fully charged) battery on it, clear the codes, drive it and see if they come back.

Graham

 

Graham,
Many thanks for your reply, yes, year would be helpful, it is a 1998.
I will get new battery fitted tomorrow and clear codes.
Yes it was perfect when I parked it in garage two years ago. I told my wife to charge battery overnight before she tried to start it first time. After that my wife says she took it shopping on two small runs before the third time when it went bad.
I will report back when I know more.
Many thanks
Phil

 

Taking all of these in toto, from a diagnostic standpoint, it seems unlikely that the ECM, ABS, and INST failed at the same time unless the engine was hit by lightning. Even then...

So that leaves TCM failure, and/or some issue with CAN bus connectivity. With these three codes, the possible CAN issues all point at the TCM or a general short in the bus, but presumably a general short and/or TCM failure would also report TCM token missing.

Inexplicably, the TCM token is not missing, suggesting it's the battery as noted above by Graham and as being addressed by y'all.

 

One more question guys, I have someone collecting a new battery today. Do I need to clear codes before I start car?
Is that necessary before problem hopefully goes away?
Apologies if my question is daft but I don't own a fault code reader.

 

From those codes, it looks like your CAN bus is not operational. There is some form of resilience built into the design of these data buses, but CAN needs 2 termination (at 120 Ohms). The 2 "end" devices are the ABS module and the Instrument Cluster I believe. From memory, the early cars have that failed solder spot in the IC that is well documented and fixable with basic soldering skills. Check the TSBs on Jagrepair.com for more details. This is not a difficult/expensive repair.

Otherwise, you need to find someone that is willing to diagnose that CAN bus. I think the basics are simple (resistance of 60 Ohms to ground to check at the diagnostics port), but then you have to go around and disconnect the other CAN modules one at a time for further analysis. On an early car, the ABS module shortcoming are well documented and would be the second best bet.

 

If it's just these codes and the tokens come back (i.e. it was a low battery problem), you should have no issue. If it's some strange electrical state in the car that persists, no guarantees. However, owing to the CAN failure fallbacks for the modules, you should not have a problem starting it to see if it functions properly. Good luck and please let us know.

 

Car came back yesterday on back of a truck. My wife said it started fine but seems to run on 4 cylinders. She is getting a lift to Pep Boys car shop today to get new battery. Someone suggested that she should touch positive to negative terminals together before she connects the battery? Is this correct?
Phil

 

Yes, for a period approaching 30 seconds.

 

Why do people lie about things? The garage my wife originally took the car to said problem was codes 1797 1798 1799. It became obvious after a few days he clearly didn't want the job, said he doesn't care about customers any more as he is retiring in a months time. It is for this reason she took car away on a tow truck to bring it home.
Yesterday my wife fitted a new battery and car behaves the same. A friend who has OBD reader hooked it up and has code P1336. Cam shaft position sensor.
Can someone (someone who still has the will to live) please advise me on what to do next.
Phil

 

That's correct for P1336:




Graham

 

The car is complaining about the cam & crank sync, rather than a hard crank sensor fault (P0335) or cam position sensor fault (P0340)



You could try disconnecting one or the other to see if either makes any difference. There is some built-in intelligence, although I'm not sure if the car will even start without the crank sensor input.

What is the car's history re timing chains?

 

Shall I just get both changed, time is of the essence!

 

Understood.
You could, but OEM parts alone are in excess of £230 (although easy to replace, so the labour shouldn't be a killer) and it's not a guaranteed fix.

 

Was this the only code (i.e. no misfire codes or anything else)? The P1336 and lack of P0335 and P040 seems to indicate that both (CKP and CMP) are functioning, and the circuits are fine, but the ECM can't make sense of the measurements coming from the two sensors. So, the workshop manual suggests checking the sensors for debris (you could also do the sensor circuit tests for grins, but the car thinks they are okay?).

You're probably going to need to get someone to look at this. I know that if I face timed my wife: "Just open the hood/bonnet, grab some tools, and I'll walk you through the diagnostics which will include removing parts off of the engine...", answer would be "Uh, no, where should I take it" (just confirmed that by asking her).

Good luck with it, please let us know what happens.

 

Well, I have ordered both parts from US suppliers, will take up to four days to arrive. And to CRBASS, thanks for input and no, apparently the only code was P1336.
My wife is not keen on "going under the bonnet" but mobile mechanics are few and far between and get scared off when you mention Jaguar. She is hoping one of our friends in Florida will help "a lady in distress".
When parts are fitted I'll update progress.

 

So Cam sensor LCA1646AD and Crank sensor LCA1640AE (both genuine parts) turned up and a friend came round my house to fit them.
Has anyone done the job of fitting a new cam sensor? My friend who is not exactly a mechanic, says it is hidden behind the throttle body and that has to come off using special tools to get to it. Is this true? If special tools are needed can anyone tell me what they are. Does anyone know of a video tutorial that I can refer to? I can only find on internet a tutorial on how to change the crank sensor.
Lastly the crank sensor did not come with its loom, only the sensor. Is that acceptable, it was in Jaguar packaging.

 

The CMPS is held with a single bolt at the back of the LH cylinder head. I've attached the JTIS R&R procedure for both sensors

Doesn't sound correct. I'm pretty sure the one on mine has the loom attached, and pictures show it. Can your friend take a pic of it and send it to you?