Low range not engaging

Hello again!

Ever since I bought my P38 the low range never worked. Because I never needed it, I never bothered to look into it.
Now, due to other issues (posted here: http://www.landyzone.co.uk/lz/f10/death-wobble-284002.html), I might be looking into repair or replace it the transfer box, depending on the most cost effective solution for both issues.

Here's what happens...
When I push the selector to the low range side, all the lights in the H gate flash and a warning light with a gear flashes together with the "Select Neutral" message in the instrument cluster and a beeping sound but low range never engages.

Where do I start checking? As I said before, I'm facing the possibility of having to change the VCU. So, maybe it's better to change the complete transfer box, as long as it fixes both issues.

If I can fix this one easily, then I'll just replace the VCU.

All help is welcome!

Thanks!

I might be misunderstanding but the gear symbol and the select neutral message is when the gearbox wants to switch to low range, if you move the selector to low range neutral and wait a few seconds 'LOW' should appear in the message centre and you're in low range

As above, you have to wait a few seconds after moving to the other side of the gate before selecting a drive gear....

If you are and you still have the message, I'd be looking at the transfer motor, Transfer ECU or the Main box XYZ switch.

Check the Solenoid for LR selection, most likely culprit. The terminals corrode badly when its not used for a while.

WilliamP said:

I might be misunderstanding but the gear symbol and the select neutral message is when the gearbox wants to switch to low range, if you move the selector to low range neutral and wait a few seconds 'LOW' should appear in the message centre and you're in low range

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I don't think the problem is me being impatience... Unless a "few seconds" are more than a minute. I could wait for 3h... still it wouldn't change to low. Only thing I get is everything flashing and beeping.

Falk said:

Check the Solenoid for LR selection, most likely culprit. The terminals corrode badly when its not used for a while.

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That sounds a good place to start... Location?

Saint.V8 said:

As above, you have to wait a few seconds after moving to the other side of the gate before selecting a drive gear....

If you are and you still have the message, I'd be looking at the transfer motor, Transfer ECU or the Main box XYZ switch.

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Can you sort them by level of difficulty?

Tilo said:

Can you sort them by level of difficulty?

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Transfer motor is the most likely culprit and not terribly difficult.

Transfer Box ECU - under the passanger seat, if it smells burnt, its toast...they do fail regularly by burning out the compnents on the circuit board...esp. if the transfer motor is stuck

Transfer Motor - these do seize up, also the switch pack on the back breaksdown giving incorrect info to the ECU

Gearbox XYZ switch - unlikely to be the issue if the main box behaves itself, but if this isn't giving the Gearbox ECU the neutral signal, or the gearbox ECU isn't telling the Transfer Box ECU that it is in neutral, the ratio won't change.

There is no solenoid, it's a shift motor. Motor seizes due to lack of use which then burns out the drivers in the transfer ECU.
Unlikely to be a problem with the actual transfer box IMO.

Datatek said:

There is no solenoid, it's a shift motor. Motor seizes due to lack of use which then burns out the drivers in the transfer ECU.
Unlikely to be a problem with the actual transfer box IMO.

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Think you'll find theres quite a few on the gearbox….

Falk said:

Think you'll find theres quite a few on the gearbox….

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There are no solenoids on the gearbox, several inside but feck all to do with the transfer box. Would you like me to send you the manual on the ZF4HP22e?

Datatek said:

There are no solenoids on the gearbox, several inside but feck all to do with the transfer box. Would you like me to send you the manual on the ZF4HP22e?

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Fair enough, i got confused with a different setup so my bad. On/in whoops - still there and can still fail. And no I'm sorted, thanks for your gracious offer

Falk said:

Fair enough, i got confused with a different setup so my bad. On/in whoops - still there and can still fail. And no I'm sorted, thanks for your gracious offer

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Said the right honourable gentleman for the south.

Grrrrrr said:

Said the right honourable gentleman for the south.

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I'm Northern, Yorkshire bred!

Falk said:

I'm Northern, Yorkshire bred!

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Said the right honourable gentleman for England!

transfer motor or multiplug on transfer motor is where id be looking first

I apologize for the revival of the topic, but this weekend I got the chance to finally have a look at this...
My first question is: My P38, being LHD, has the ECU on the passenger side or driver side?
Under the driver side (so, left side), there's two CU's, one Bosch and the other I cannot see as it is under the Bosch CU. I found a socket disconnected from the bottom CU. Thought that might be the answer to my problem, but no. Connected it and everything stayed the same.
Got under the car and checked the motor socket. Didn't see any clear signs of corrosion or bad contact. Anyway, cleaned everything and plugged back in. No changes.
I was running out of time to remove the motor, so that's where I'm turning next...