Hi everyone,
So sorry if this isnt the right place for this post, still getting used to the site.

We have a 1997 XJ8 4.0 V8 LWB. The car has 78k miles on the clock. The car was ok a week ago, but felt very sluggish from standstill but once up and running on open roads it went as it should. The car had traction/stability control faults coming up and the alternator wasnt charging the battery. So we brought a brand new battery and alternator, and we have not had the faults come up again. But we now have no warning lights when idle but as soon as the accelerator is touched we are getting 'gearbox fault' and a amber light. I fear the gearbox has gone or need repairing and car is in limp mode explaining the slow acceleration if the car locks in 4th/5th and ok when up and running. Is their a warning if the car is in limp mode? Any suggestions would be appreciated.
Thanks

 

Is the MIL on, and if so, what DTCs are stored in the system? Quite often the cause of these situations are battery-related, or are due to a poorly performing engine.

Since the control modules communicate with one another, the TCM may be 'protecting' the gearbox until any engine performance issues are corrected.

 

Than ks for reply, there is no Check engine light if thats what MIL means, it comes on when the ignition is on but not after it starts. sorry but im not the best when it comes to the mechanical side of cars Someone is due to come to the car tonight to read the codes if they can. We also noticed the lights behind the rev counter and so on dim when the accelerator is pushed, whilst in park. Thanks again for reply.

 

The Malfunction Indicator Light (MIL), often referred to as the 'check-engine-light' or 'cel' will come on if there is a fault over a certain number of starts, or under various conditions.

Once you have the codes read, write them down and post them here so forum members can assist.

Check connections at battery as well.

 

Hi
Had the car scanned today and the only code we had is P1793
Any advice is appreciated
Thanks

 

If the battery was replaced along with the alternator, check all connections and perform a load test on the battery. It is possible the battery is not at full capacity.

 

Got the battery v checked and its now OVERcharging. when cold we got 38v!! then 16-18. Been advised not to drive the car incase of doing more damage. Would this explain the limp mode and all the faults that come up? It seems someone (either alternator supplier or mobile mechanic) has had a problem along the way. Had brand new battery and recon alternator last week due to fault we had battery not charging. One thing after another so far since we brought it. Really appreciate your help

 

From my experience, it is always better to have the alternator/generator/starter removed from the vehicle and serviced by an automotive electrical specialist shop.

An overcharging condition can ruin many items in addition to the battery. Before proceeding, have the alternator replaced with one that is functioning correctly and install another battery as the one that has been overcharged is most likely ruined.

 

I've moved your thread from General Tech Help to X308 forum. This is the place to post tech questions about your model.

Graham

 

CozDan19,

Welcome to the Jaguar Forums. I'm sorry you're having such trouble with your Jag.

At the link below you can view the Diagnostic Trouble Codes for your transmission, and you will see that the P1793 DTC can be triggered by either very low or very high voltage. Hopefully, if you can resolve your voltage problems, your transmission issues may clear up as a result:

http://www.jagrepair.com/images/Auto...%201997-99.pdf


Cheers,

Don

 

Thanks for all your help. Took the car to a garage for a full check over, turns out the re-con alternator is playing up. So a brand new one ordered to be fitted Monday morning. Do you think this will take the car out of limp mode so we can get back to driving it properly? And should the codes go aswell? Thanks again.

 

Got car done today, now drives brilliant. Nice to have it as it should be. Now just to spend some time cleaning and polishing it.