Transmission Controller diesel version

I'm having trouble with the gear change on my 2001 DHSE automatic. The gears won't change up. At about 3500 RPM the gear reluctantly changes up and the revs drop off but after the throttle is pressed the revs shoot up again. The gearbox is obviously running in low gear. Moving the gear lever has no effect.

The fault was thought to be the transmission controller and as mentioned in a previous post the garage fitted a petrol version transmission controller (diesel version not available) and the gears changed up and down OK but the changes were clunky due to changes being made at the wrong settings.

I have now fitted a replacement diesel version with the right specification and again the gears won't change up same as with the old unit. No fault codes are logged so seems there is something else causing the problem. Can anyone shed some light on the problem?

Transfer box ECU might be the problem, or bad connections or the speed sensors, or the box is shot. Autobox ECU seems pretty reliable. Not heard of any failures.

Thanks for your reply Datatek. I can't understand why the petrol version transmission controller works fine though obviously the speed controls mapped into the controller are not suited to the diesel version. I suppose it is possible that I have got two faulty Diesel controllers which is screwing up solving the problem. If there was a problem with any other ECU would'nt that prevent the petrol version working?

parranger said:

Thanks for your reply Datatek. I can't understand why the petrol version transmission controller works fine though obviously the speed controls mapped into the controller are not suited to the diesel version. I suppose it is possible that I have got two faulty Diesel controllers which is screwing up solving the problem. If there was a problem with any other ECU would'nt that prevent the petrol version working?

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The transfer box ECU affects the way the autobox works when in low range. It's possible there are significant differences between petrol and diesel autobox ECU's so maybe a duff transfer box ECU would not have the same effect with a petrol autobox ECU fitted. Certainly there have been some funny things reported with duff transfer box ECU's.

I should mention that the low range gears work fine with both the petrol and the diesel version Transmission Controllers. Its the normal range thats not working properly. Would a fault with the engine ECU cause the problems I'm getting? The engine starts and runs fine and there are no faults recorded with engine connected to a computer.

parranger said:

I should mention that the low range gears work fine with both the petrol and the diesel version Transmission Controllers. Its the normal range thats not working properly. Would a fault with the engine ECU cause the problems I'm getting? The engine starts and runs fine and there are no faults recorded with engine connected to a computer.

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Pretty unlikely. I would still look at the transfer ECU, it can cause all sorts of problems. Just ****ing in the wind really, needs diagnostics live data.