Auto Gearbox Sport Mode/Kickdown Problems

Hi,
Just bought a 1995 P38 4.0, the only other car I've driven before it was a Citroen C1 so quite a difference!

Today when accelerating quite hard (out of sport mode) the gearbox kicked down and went fine until it just sat banging off the limiter in 3rd I think (something like 5000 revs at 70) and it wouldn't change into the next gear despite letting off the accelerator. I tried stopping and i set off again and again it wouldn't change up into 4th. So I stopped again and turned it off and back on and this time it finally went back to normal. Any ideas why this is happening, it's banged off the limiter before with the accelerator full to the floor but before it changed up when I let off the accelerator a bit.

Another issue is that it doesn't kick down in sport mode. Kicks down fine not in sport mode (apart from the above issue). The sport mode light seems to be very dim but i don't know if that's just a light bulb issue.

I'm planning to change the gearbox oil soon to see if that helps, but any other suggestions would be appreciated.

Thanks,
Jack

Sticky govenor / valve. Give it an oil and filter change and then do it it again after running for a few miles.

Check your TPS sensor and the plug/connections.

throttle position sensor give the connector a clean (best)(or wiggle)

rewmer said:

Sticky govenor / valve. Give it an oil and filter change and then do it it again after running for a few miles.

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There is no governor, it's electronic. Check you have enough oil in the box.
Otherwise bad connections earths etc. Battery OK?

Datatek said:

There is no governor, it's electronic. Check you have enough oil in the box.
Otherwise bad connections earths etc. Battery OK?

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I think the oil level is fine. Ill check later.

Battery seems fine, starts fine all of the time.

One thing i did notice today is that when the box is in sport mode the symbol in the message centre doesn't change depending on what gear is selected. Where as out of sport mode the message centre symbol changes depending on the gear selector.

Forgot to say that the previous owner has removed fuse 4 because the transfer box motor was broken or something to stop the gear selector lights flashing. Could this have any affect on it?

Thanks for the help.

jacckk said:

I think the oil level is fine. Ill check later.

Battery seems fine, starts fine all of the time.

One thing i did notice today is that when the box is in sport mode the symbol in the message centre doesn't change depending on what gear is selected. Where as out of sport mode the message centre symbol changes depending on the gear selector.

Forgot to say that the previous owner has removed fuse 4 because the transfer box motor was broken or something to stop the gear selector lights flashing. Could this have any affect on it?

Thanks for the help.

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If the transfer box ECU has failed it can certainly cause problems, it's known failure item, lives under passenger seat, check for smells of burning.
The motor position switches can also affect what is going on.

I'm not sure if the transfer box ecu has failed, the person I bought it from said it was just the motor. I'm guessing since the fuse is removed its equivalent to it being turned off.

From reading RAVE it looks like the sport mode problem is more than likely also related to the transfer box ecu fuse being removed.

I'll wait till I've got the motor and oil changed and see if there's any improvements.

jacckk said:

I'm not sure if the transfer box ecu has failed, the person I bought it from said it was just the motor. I'm guessing since the fuse is removed its equivalent to it being turned off.

From reading RAVE it looks like the sport mode problem is more than likely also related to the transfer box ecu fuse being removed.

I'll wait till I've got the motor and oil changed and see if there's any improvements.

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If the motor fails, it often takes out the drive transistors in the ECU.

There is a shaft speed sensor in the gearbox and a vehicle speed sensor in the transfer box. Both ECUs talk to each other. Whether the transfer box ECU being shut down has any bearing on this i don't know. But it is a distinct possibility.

I've replaced the transfer box motor today and put fuse 4 back in place. I don't get any flashing lights on the H-gate when in high range anymore now.

When I try to shift into low range though nothing happens, no flashing lights, no beeping, nothing. Does this sound like my transfer box ecu is broken?

On the plus side the gear indicator in the message centre now does display sports mode when its activated, but still no kickdown in sports mode which makes it useless.

Jack.

jacckk said:

I've replaced the transfer box motor today and put fuse 4 back in place. I don't get any flashing lights on the H-gate when in high range anymore now.

When I try to shift into low range though nothing happens, no flashing lights, no beeping, nothing. Does this sound like my transfer box ecu is broken?

On the plus side the gear indicator in the message centre now does display sports mode when its activated, but still no kickdown in sports mode which makes it useless.

Jack.

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As I said, if the transfer box shift motor fails (usually it seizes through lack of use) it often takes out the transfer box ECU. Take it out, take the lid off and look for damage.

As I expected you were right

ECU is burned inside quite badly, so a new one has been ordered.

jacckk said:

As I expected you were right

ECU is burned inside quite badly, so a new one has been ordered.

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Should have looked at that first, probably nothing wrong with the old motor, just stuck through lack of use, nothing a drop of oil would not have fixed.

New transfer box ecu installed today and all problems are now fixed. The sport mode light is lit up correctly and no longer dim, it doesn't bounce off the limiter when using kickdown in normal mode, kickdown in sport mode works nicely and so does low range.

Hello I got a range rover 1998 p38 2.5 dse and the problem is when I kick down it drops a gear then when it picks up speed and changes up a gear it revs to 3,000 then won't go any more I have to take my foot off the gas then reapply the gas before it will continue you to pick up speed I've only had the car 2days helppp please

OthedriverO said:

Hello I got a range rover 1998 p38 2.5 dse and the problem is when I kick down it drops a gear then when it picks up speed and changes up a gear it revs to 3,000 then won't go any more I have to take my foot off the gas then reapply the gas before it will continue you to pick up speed I've only had the car 2days helppp please

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Sounds pretty much the same problems as I had. Remove your transfer box ECU and open it up and check the condition of the circuit board inside. You can access it from the rear of the passenger seat by removing the vent that goes under the seat.

You can pick up new ones pretty cheap on ebay. It's also worth making sure your transfer box motor isn't siezed because the ECU controls that and I've heard that it being seized will cause it to burn out. If it goes into low range and back to high range then the motor won't be siezed.

OthedriverO said:

Hello I got a range rover 1998 p38 2.5 dse and the problem is when I kick down it drops a gear then when it picks up speed and changes up a gear it revs to 3,000 then won't go any more I have to take my foot off the gas then reapply the gas before it will continue you to pick up speed I've only had the car 2days helppp please

Click to expand...

Check if there is any oil in the gearbox. Sounds like the Drive clutches are slipping. If the oil level is good, you could try an oil and filter change then add some Lucas Transmission Fix. It may do the job, it has on mine. To check the oil level, the engine and gearbox needs to be cold, you check with the engine idling and after moving the gear lever through all positions and returning to park. Otherwise a recon box sounds likely. Ashcroft Transmissions are the place to go.
Always a good idea as a noob to introduce yourself and give a rough location, there maybe someone nearby who could take a look.