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For the past two months, I have owned a Jaguar XJ8 X350 - 4.2 V8 with a whopping 322,000 km on the clock.
Ever since I bought the car, it occasionally throws a "Gearbox Fault" message along with a "Park Brake Error" at the same time. When I read the codes, it shows P0705. After stopping and turning the ignition off and on, the message disappears every time, allowing me to continue driving.
This happens at irregular intervals—sometimes within 100 km, but other times only after 500 km—completely at random. Because of this, I’m not assuming the sensor is failing, but rather that the tension on the shifter cable might be a bit slack, occasionally triggering this code. I've read that this can happen at high mileage.
I would change the fluid and filter right now unless you have some records showing it has been done.
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I think, but don't know for sure.. that the oil is changed quite recently.. because there is no rust at all on the bolts.. I see lots of posts where the bolts become rusted because of the salt on the roads.
Maybe just do a fluid level check then? You could put a dab of fluid on a white towel to get an indication of the condition too.
Oh and the old stand by question. How old is your battery?
Take a look at this thread as you may have a mechanical shift cable issue. One thing to check are the 2 small 9mm or 10mm bolts holding the shift cable to the transmission. If these are loose or missing things won't line up between the shifter in the console and the transmission itself. The code is saying there is a miss-match.
Cable stretch has also been proposed as the problem.
Here are where the bolts that attach the shift cable. I would get under the car and take a look at the drivers side of the transmission as this picture shows.
Here is a small thread that talks about the shift indicator which can point to the J-Gate shifter having a problem. Code P705
Here is a thread on an S-Type talking about the range indicator inside the TCM which is also mounted inside the transmission. This reads the position of the shifter cable attached to the outside of the transmission. Range Indicator and TCM
Here is a VERY interesting thread from a Land Rover forum concerning the ZF 6 speed. With some great pictures if you plan to troubleshoot this yourself. I did NOT know the shift cable rotates as well as moves in a linear fashion at the transmission. Land Rover Shifting Problems
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Clubairth1, thanks for the post! I'm gonna check the bolts next time I'm under the car.
Funny that you mention the battery because I have been monitoring this one. I don't know its age... What I do know is that when I measure it, it holds too little voltage if I use the seat and window heaters for a few consecutive days.
I've been testing this theory by not using my seat and window heaters for a week. Guess what? No fault codes. The day I started using them again, the fault code appeared. Also, my seat heater throws codes B1221, B1222, B2371, and B2372. It's a value out of range—maybe it's drawing too many amps?
That same day, I put the battery on the charger, and it required quite some charge, so I can conclude the battery is bad.
Checked the alternator voltage, and it was a steady 14.3 volts.
I can't really relate the battery to that specific code, but it's an easy fix to replace the battery.
Clubairth1 is right, a healthy battery is fundamental for these cars. And do not try to relate a fault with the battery, it will only give you a headache...
There really are a lot of faults that can pop up that you would never relate to the battery. So, if the fault disapprears with a new battery, just be happy that it could be solved easily and enjoy the car
Great troubleshooting MarcoB!
You might just get off lucky with the battery too as Thomas-S posted above. It's still surprising how many things are affected by a marginal battery. Especially when the car starts and drives fine.
Can you post back what the cars voltage is after sitting all night? I guess if your replacing the battery there is no need.
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You state in the beginning that you have had the car only for two months, and as you have not answered Clubairth1s question regarding the battery's age, I assume that you do not know how old it is.
I have replaced the battery and now drove about 800 kms with it; trouble free!
Haven't had the gearbox fault anymore, this shows how important it is to have a battery in good condition in this car!
I have had that and it's surprising how far the corrosion can travel inside the wire insulation. Might be worth stripping it back a bit to check? You might need a new cable assembly.
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I have had that and it's surprising how far the corrosion can travel inside the wire insulation. Might be worth stripping it back a bit to check? You might need a new cable assembly.
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I've replaced the whole cable for a new one. Don't think it was worth saving.
And taking into consideration how sensitive these car are regarding battery voltaqge, I assume that the old cable increased the problems that the car had.
Thnaks for the information, it's one more item to check when the car has battery problems.
P0705 - Gearbox problem
