Jaguar Forum banner

1 - 11 of 11 Posts

·
Registered
Joined
·
4 Posts
Discussion Starter #1
I have a 2010 jag xf 3.0D
I have a issue where the gearbox fault light comes on it happend the middle of last year but turned car of and it went away until now it came on as I was driving I accelerated a little and it tried to drop a gear and the light came on had no drive I pulled over and after few moments it onli had 1st gear turned car of went away I had it plugged in and had about 25 codes on there had it wiped
Around 24hrs later it came back on in the same place as I was driving last time seemed to struggle down shifting I had driving the car around most of the day and was fine no problems
I had it plugged in again to see what codes and brought up
U0155
U0415
U0422
U0402
U0140
P2704
Got it cleared and had battery tested it was round about 11.7 11.8 when off and round 14.6 when on
The light hasn't since came on but I have been causus
I was driving and I D mode it was OK till when let of throttle the rev counter would drop to 0 then pick up when accelerated so put in sport mode and change to manual revs we're fine car changes fine
Can anyone suggest anything or have had similar experience
 

·
Registered
Joined
·
4 Posts
Discussion Starter #3
Did you have the same issues because it's just baffling me I'm going to check battery again to double check but considering it
 

·
Registered
Joined
·
285 Posts
11.7 is very low - it should be around 12.5v. Low battery does often give a gearbox fault warning, but it could also be real. The fact the battery is low, but seems to be charging OK makes me suspect the battery. Is it starting OK in this cold weather with 11.7v?
 

·
Registered
Joined
·
4 Posts
Discussion Starter #5
11.7 is very low - it should be around 12.5v. Low battery does often give a gearbox fault warning, but it could also be real. The fact the battery is low, but seems to be charging OK makes me suspect the battery.
Yh I would have fault if it was gearbox fault then I wouldn't drive or select gear properly and the light would come on more but the gears seem fine and drives like it always have
 

·
Registered
Joined
·
228 Posts
Did you have the same issues because it's just baffling me I'm going to check battery again to double check but considering it
pretty much as antf says- once i was left stranded when my battery was too low to start car, all manor of error messages including gearbox fault, so replaced battery & alternator shortly afterwards, tis good as gold now

Sent from my SM-N960F using Tapatalk
 

·
Registered
Joined
·
19,092 Posts
Yup, battery.

Sent from my SM-G977B using Tapatalk
 

·
Registered
Joined
·
285 Posts
Yh I would have fault if it was gearbox fault then I wouldn't drive or select gear properly and the light would come on more but the gears seem fine and drives like it always have
You mentioned you only had first gear, which could suggest a 'real' fault, but maybe I misunderstood. I still think the battery is the problem as you have tested it and it is reading low. You could try charging it, but if the alternator is working, as it appears to be, it sounds like a new battery is needed. Does it have a date on it? If the original battery it will be branded Jaguar and may have a date stamped on a terminal post.
 

·
Registered
Joined
·
1,673 Posts
Definitely need a new battery as a first step. It it were holding a charge correctly it wouldn't be dropping from 14.6v with engine running to 11.6v with it off, it should drop to high 12.x volts. As others have said, low battery can cause all manor of faults to be falsely stated including gearbox faults.
 

·
Registered
Joined
·
533 Posts
P2704 is quite explicit it is a friction element fault, could be low fluid or even odd inflated tyre's. Battery is a bit low though, have a good look around for any leaks. It seams that fault is likely to be intermittent and does just what you described.
If the battery is going to play up it will do it with this weather so it is a good place to start.
 

·
Registered
Joined
·
533 Posts
Looking again at some of the codes, you have implausible or erratic signals from the ABS module to Power train module also the same from Power train module to CJB. It does point to a Gearbox issue. Whenever CJB is mentioned on this forum alarm bells start ringing. One of the codes is instrument to CJB I think? which is a communication error. Once again the CJB comes up. So it may be worth having a look at that for water ingress. Plenty of info on hear of what causes it and repair.
I still hope it is just the battery but best to keep an open mind.
 
1 - 11 of 11 Posts
Top