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P38 Low Range


beng
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Hi,

New and original problem has reared its ugly head this week. My Manual P38 has decided not to go into low ratio - well not quite that simple... Press the button and it does something, if you try and drive off it seems to have engaged but says SLOW DOWN, doesn't actually say LOW on screen.

Very occassionaly it seems to go in, but only once in a while.

Has anyone come accross this one before?

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need to read the rave manual , but at a total first pass guess, it could be the little switch that detects the lever has moved is not getting fully pressed all the time.

so whilst its physically engaged low, the switch is not reporting back to the ECU that it has moved properly.

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Yes - it does move through a neutral point. Actually in going between high and low positions, it passes through 4 other zones of position which the transfer box ECU recognises.

There is a big motor on the back of the transfer box which drives the engagement of the high/low gears :

(numbers 2 and 3 are the wrong way round i think )

p38transfer03.jpg

And you can remove the motor pretty easily:

p38transfer04.jpg

The main description of how it works is outlined below. Basically, the ECU knows the position of the motor by means of a binary signal coming from the motor...

p38transfer02.jpg

And the wire colours and binary code from the switches are here:

p38transfer01.jpg

So whats wrong with your car? I dont know. Its possible that the system is phsycially not engaging due to lack of use . . . or its possible that the system just doesn't know its engaged as the binary code is screwed up?

One you give a while to engage, can you phsyically drive off ? It'll be readily apparent if your in low or not.

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Extremely Helpful - thankyou very much.

Yes if I try and drive off it is in low ratio (the two times I have tried it), will whip the motor out and give it a clean and have a look at the binary sender unit :-)

Thanks again

:)

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