Gearbox fault codes

Hi, I know this has probably been asked a thousand times, but I've done a search and it's not coming up with any threads. My p38 4.0 has got gearbox faults apparently, according to the dashboard anyway. Does anyone know a way to read the faults codes or wipe them without going to get raped by a dealer. My mate has a scanner but will only read the engine management and abs system.
Any help is much appreciated. Thanks

hi matt do you have the codes?

99% of the time it will be low battery voltage - check and sort this before you worry about codes in the gearbox ecu.

Hi, no I don't have the codes, thats what I want to find out to do. Whether you can read the transmission ecu without any specialist equipment. Also eightinavee it's got a brand new battery on it. The other gearbox fault I found in the short period I've drove the vehicle. Is when Iput it on my drive I reversed it on, then went forward, then went to reverse again but it wouldn't move. I turned the car off, left it for a couple of minutes, and then it went into reverse.

check the voltage output of the alternator first, then check fluid in transmission, if not any of them then you will have to go to a fella with the kit!!!

mattfletcher said:

Hi, no I don't have the codes, thats what I want to find out to do. Whether you can read the transmission ecu without any specialist equipment. Also eightinavee it's got a brand new battery on it. The other gearbox fault I found in the short period I've drove the vehicle. Is when Iput it on my drive I reversed it on, then went forward, then went to reverse again but it wouldn't move. I turned the car off, left it for a couple of minutes, and then it went into reverse.

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Still say the same - check the voltage,new batteries are often only partially charged,a few hours on a P38 that has a poor charge rate or battery drain issues and its all over.Without a decent voltage at start up the gearbox fault message is the first thing you will see.
No,you cannot read autobox ecu faults with any old scanner,it needs to be Testbook,Autologic or Rovacom,cant think of any others with even a chance.Plus the ecu is very difficult to talk to at the best of times AND is very fussy to connect to if the battery voltage is low.
Any decent Indy should be able to check the voltage/charge rate/drain rate and read the EAT codes for £50 or less.

Hi Matt,
All the help the better, i have had a 'gearbox fault' with my 96 P38, since i bought it (knew ithad the fault). I have bit by bit gone through the car checking all the connections.
There are many computers on the rangie and they all work together, an error in one will bring all sorts of faults.
The auto transmission is reliant on the engine performance, revs, torque etc.
The faults I found:
1) Behind the kick panels in the foot wells the are a group of multiplugs, they are prone to corrosion, any bad connection will send false reading to the Becm.

2) The fuse block in the engine bay, take the cover off and pull out relay 7 (yellow) if the holes that the relay plugs into looks abit worn or heat damaged, means the fuse board is faulty.

After lots of fault finding after repairing the fuse board, the 'gearbox fault' message has never been on.

i did have the similar fault, some times the message came on as soon as i started the car, some times when i started moving, there was no pattern to the cause.

i found the following web site very usefull, its where i found the fault with the fuse box and it worked, did not cost me any thing to repair. Range Rovers.

Oh and if you find the multi plugs corroded in the foot wells, cut them out and replaced them, for your info i replaced them with a ready made harness i got from maplins, it is for computers, a 21 pin ATX extension lead, it has a male on one end and a female plug on the other so you can cut the wire in the middle and solder the harness in and still have the option of unpluging if required.

Sorry for going on a bit, but hopefully it all helps and saves money hopefully.

Cheers Rich