2001 Jaguar XK8 100,00 mi


Ok, the XK8 was not driven for about two weeks. Sat in the garage. It Was driving perfectly before the two week break. Got in to start it and it wont turn over, ignition does nothing. All gauges light, and lights radio etc work. Got the following errors on the dash...


- Engine Failsafe Mode
- Incorrect Part installed
- Low Break Fluid
- ASC/Trac warning
- Gearbox failure


-Tried to pull codes, the OBDii Port is dead but was working before.


NO parts were installed no work at all was done. It sat, and I tried to start it. I have no idea where to even start without my old OBDii tool.


ANY HELP to point me in the right direction would be apprieciated.

 

I'll bet it's a low battery. Jags do not like low batteries and will throw all kinds of codes when the battery is low. Your car sat for two weeks and even when sitting the Jag will use the battery.


Mark

 

Yea that was my first thought as well. I didn't mention that after it didn't start this morning I threw the charger on battery and let it charge all day. Its only a 6 mo old optima and charger said it was full after a few hours ....
thanks!

 

Even new batteries can go low. I would test it to be sure. Next step would be to check the main battery ground. This is also a frequent problem area.

 

ok will check tomorrow...thanks!!

 

Is there any noise at all when the key is turned (clicking, etc.)? Do the lights dim when you turn the key? If you're getting absolutely nothing, check all the power leads carefully, especially the ones in the trunk forward of the spare. If you have a lightbulb or multimeter, check for voltage under the hood at the charge terminal. I think it's on the pass. side under a cover. If you have voltage there, it may be the starter has frozen on a dead spot. Sometimes tapping it with a hammer can help. Very hard to reach on our cars. Good luck.

 

This morning, I took the transmission control unit out. Tried to start the car and it started right up but obviously had plenty of errors. Transmission was in true limp mode. So my thought is the Tranny Control Unit is fried.

When I got home this afternoon for grins I put Transmission Control Unit Back in. Car fired right up all gears working and drives fine. No codes no nothing.


Sooo...Im a little apprehensive to drive it too far. Any last thoughts before I give it a go?

 

How did you decide to focus on the transmission Control Unit?

I'm thinking your problems started with a low battery condition or poor connection somewhere...

You might try a "hard reset" before you venture out. Other than that I'd give her a go.

 

Just a shot in the dark but I have never gotten the transmission failure dash warning before nor the incorrect part installed. Thought I would try the tranny computer then the ECU. And yes, I did the battery disconnect reset along with the code scanner reset. Will try it next week since Im out of town.


Thanks Again to all the threw out suggestions its very much appreciated. WIll keep you all informed ....

 

When you put the TCU back in you may have cleaned a bad connection. I would disconnect the neg. battery cable, then clean both the ECU and TCU contacts with electronic cleaner, put it all back together and give it a try.
You did disconnect the battery before removing the TCU previously, I hope. I agree with spurlee that the battery may have been your original problem. It's possible that the r&r on the TCU was co-incidence, or maybe the having the ECU re-address the TCU was also a factor.

 

When you get wildly unlikely codes - multiple ones especially - and general system type faults you most likely have an electrical voltage situation on your hands. Especially after sitting a while.

Do the simple stuff first - check your major grounding points by loosening them and reseating. Put your load tester on the battery and see that it is up to the task. Check and reseat any applicable relays and check fuses. Use your meter to check the charging system. Any weird aftermarket electrical items installed? Look for parasitic draw on the battery.

Personally, I'd look again at that Optima battery. I might be old school here but isn't that a dry cell type battery? Shouldn't make a difference but it's not what the Jag system is looking for...

Be systematic and you'll get it easily.

 

The ground strap on the passenger side transmission to frame is corroded green and shot. The funny part, you cant take the tranny bolt out all the way to remove the old one, so I cut a slot in the new one and installed it tight.

Your kitty will love the repair when your done, your inside lights will be brighter and everything.

Also check the red power wire driver fuse box nut,It gets loose.

I had all kind of trouble like you until that ground got fixed .

 

The Optima is an AGM battery with superior characteristics compared to a flooded lead-acid type. Doesn't mean it can't go bad, though, or the charging system may not be up to snuff.

 

I stand corrected! We use AGM batteries in the jet ski shop where I work in the summer. They are, indeed, much better in hostile environments than lead-acid types.

I have noticed, though, that they are not at all forgiving when deeply discharged. I wrecked a brand new one by letting it sit all summer and it would never charge back over about 4V.

In the shop we are doubtful of the long term life of any battery that comes in showing less than 10V...

 

Took it out today. Started up and seems to run fine. Tranny shifts fine, no clunks sounds or any unusual noises. The only problem and Im sure its related somehow is the OBDII port no longer functions. It will light my diagnostic tool so theres power but as it cycles through its startup checks, it get to the end and says connection problem. But for now that is a side note and will do some research tomorrow. Also tomorrow she will get a new tranny filter and fluid. Hope it still runs after that hahah...
thanks again to all the supplied suggestions and advice. Very much appreciated guys!

 

Good!

Test drive it over to Pep Boys and have them put a reader on it. I'd like to eliminate the reader itself as your OBDII problem.

Transmission service is a smart idea.

 

Just an FYI for all 5HP24 tranny people out there. Change your fluid when you're about 100,000. I changed mine yesterday and the old stuff was like sludge. It was charcoal colored and thick as honey. No big chunks in the pan or on the magnets, just the usual dust sized metal flakes. Important thing is to change it!