My recently purchased 1998 XJ8, with 35k miles on it started playing games with me.

1. A few days ago I started the engine just to find out that all the control lights are ON, including Check Eng/ABS/Brake/Transmission Fault/ Failsafe Engine Mode and it is not possible to change the shift stick from park to any other gear.
2. A few hours later, the same thing
3. A few hours later, it started, but ONLY the check engine was on. I read online that Jag is sensitive about the battery, so I drove to Advance Auto Parts right away to check the battery + error codes. Battery tester showed that the battery has no problems. Computer showed two errors P1638 and P1111 (pic attached)I drove back home. It drove nicely without any problems.
4. Today, I started the engine, and here we go again, the same issue, all the control lights are ON, including Check Eng/ABS/Brake/Transmission Fault/ Failsafe Engine Mode (pics attached)

Previous owner was an original owner that really cared about the car, always serviced it at a Jag dealer. Last year, when she took it for a regular service, dealer recommended some additional services, so she said yes to everything. Picked up the car 4 days (and $4,700) later.

Any ideas?

Wife: “I told you not to buy this old car”


Scan from Advance Auto Parts

 

DTC guide for you.

 

I had this same code on Jag 3 P1638 plus a code P1795 about a month ago: P1795 CAN transmission control module/ instrument cluster circuit malfunction

I replaced the instrument cluster and have not had a code since. The weird thing is I had that some code and condition on this car sometime last year and with Jag 2 a couple years back as well. Both times replacing the cluster cleared the problem. I don't recall seeing a mention of an instrument cluster failing on this forum or a mention of the cluster being a point of failure with these cars.
It seems like it would be a communication error in the CAN bus and if so, perhaps the RS232 chip is bad? Was thinking of ordering a couple and replacing it on one of the failed clusters and seeing if it fixed the problem.

 

I don’t have P1797, do you believe I still need to replace an instrument cluster? Easy replacement? And, is there an easy way to verify that this is the problem?

I still have my 2003, Jag xj8, would it be possibly to switch it just to test for a few minutes?

 

I don't know if AJ26 and AJ27 INSTPKS are 'swappable' but look at the VCATS!!!!!!!!!!!!!!

 

I’m kind of lost on this one. Do you guys have any other ideas on how to approach this problem?

 

I took the pics from both of my jags. Blue one is the one that has the problem. Gold one is the one that I possibly could use the part from for testing.

 

The connectors are different on a 98-99 from a 2000-2003 so you cannot swap them. All of my instrument cluster problems have been on my 2000 VDPs so I have no experience with this problem on a 1999 car. It is easy to change though and it might not be the problem. I think there were more DTC checks on the 2000-2003 cars since that code is not listed on a 1999 car.
The CAN buss runs through a number of components so it could be something else entirely. I wonder if someone that has a super duper coder reader could query the buss and locate the source of the error? I've always just guessed and hoped I got it right....

I've attached a diagram of the CAN buss that I found from someone I think on the JagWeb site...

 

banar, what David N. Warner shared is right on the money, the CAN diagram provided doesn't deviate from Figure 21.1 in the X308 Electrical Guide. I've not experienced an IPC failure, but it sounds as though "it's a thing" for some, and what you're describing certainly sounds like a disruption in the CAN network. If you want to check wiring before replacing your IPC you could work your way away from it by checking harness/connector at GSM -> ECM -> TCM -> ABS/TCCM. None of which terribly difficult to get to, the twisted pairs of green and yellow make them easy to spot, with any luck you may find corrosion or something frayed.

 

I'd start with the ABS connector. It's easy to remove and right there in the front right side of the engine bay. Spray it out with contact cleaner and re-install. You really need to disconnect the battery first! These cars are very sensitive to electrical problems.

Also, after the battery is reconnected, turn the key to the on position, (right before the starter engages), position and let it sit for about 20-30 seconds. Then hold the accelerator pedal down for another 20-30 seconds; let it up and then start the car. This will reset the throttle body adjustments and it won't rev up like crazy.
I got this information from someone else....much thanks to this forum...

 

Nothing really helped. Even though I did not complete the steps that @David N. Warner recommended.

I just dropped it off at the dealership. Let's see what they say. I will update you guys once I have more info.

Also, I think it's time for me to invest into a nice OBD scanner. Any recommendations? I like when it shows the info on iPhone, but not needed, I just want to make sure I have a good scanner.

 

I have an iCarsoft i930 which is for Land Rover and Jaguar exclusively. It is pretty good but I wish I had spent more on a better unit that would show a live graph at least or could program keys! It does read all the modules including ABS and the instrument cluster among the others. There are some checks that don't respond since they are not available on this car. The reader would probably read them on a newer car.
As I mentioned on this forum, I have had to replace the instrument cluster on Jag 2 once and Jag 3 twice due to CAN DTC codes popping up with the attendant "Restrictive Performance" message. Swapping the clusters stopped this DTC. I generally keep the unit in my car in case I get a code though it has not thrown a code in at least a year..... until the cluster problem about three months ago. No code since then....

Hope you get the car repaired and back on the road soon!

 

When you say you wish you spent more on something better, is there any specific model you have in mind?

Also, is the scanner good for other cars, like Lincoln? or only LR and Jag?

 

Here's an update.

I decided to drop it off at Jaguar dealer on May 23. They kept the car until Jun 18 (yesterday). They said that it's a tricky problem, but updated the computer and cleaned all the connectors related to the brake module.

I tried starting the car this morning, but the problem is back - the same thing. It's very disappointing.

Any ideas or recommendations?

 

Wow!... When a dealership says "it's a tricky problem"...that is scary. I would have expected them
to at least suggest how to proceed. Lucky for you we have some great techs on this forum that have
seen most issues related to these kinds of problems. If you don't understand something, then you
might have to ask them to "dumb it down" a bit, but they are always willing and mostly accurate.

 

Thanks Randy,
I'm trying, but so far no solutions.

 

Hi, i know its two years later. Did you get your car back on the road?