The delay in the error code being produced might indicate something like continuity loss when the solenoid gets warm, so if you're going to check the solenoid resistance make sure you do it under the same conditions that the fault code is generated under - sorry if that's obvious but thought it was ...

Thanks for your reply - It'd be a shame if the coupling wan't available as the rest of the box appears to be in good order, and a new coupling would be a known quantity. I don't fancy shelling out for a complete new transfer box, so that would have to be second-hand, and I'd be taking a chance on ...

Hi Simon,

In answer to which solenoid is which and where they are have a look at the posts I've added to the Transmission not changing up to 4th and lock-up not working thread.

I found the solenoid resistance diagram I was thinking of (link below), it also shows the solenoid locations, so the lock-up solenoid is the one on the bottom on it's own (the other 4 are on the top). That's good news in one respect as it means it could likely be changed without having to remove the ...

Hello again,

So after a week away in the bongo (which now has a fully working automatic transmission) I am pretty convinced that the viscous coupling on the 4WD transfer box is seized. So far all I have done to test this is the "turning in a tight circle in a car park" test, when I get a chance ...

Just to add, the valve body comes out in one piece, don't take it apart/split it (apart from removing the broken solenoid of course). This is what it looks like when removed, you can see some of the solenoids on the right hand side:

Bongo AT Valve Body

Those 3 springs you can see on the top are ...

Hi Simon,

Sorry for the delay in posting back, I've been away, in the Bongo (a new thread to follow regarding a new issue but enough of that here).

This image shows the location of the relay on my van:

Link to shared image of relay location (google drive).

However I suspect that your issue is ...

When I purchased the van I had never driven an auto box, so was almost unaware that when it went into 2nd the revs would rise (over rev) to 2500-3000rpm then change, this was with very small amounts of pressure on the accelerator, if I accelerated away the problem did not happen, I also noticed ...

I agree, it does seem a bit keen to change down, I've not tweaked the TPS yet to see if that helps. I'm not sure how much scope there is to make a massive difference with the minimal amount of adjustment available on the TPS.

A word of warning - If you ever decide to play about with something to ...

I should have added that the TPS signal at the ECU looked ok, it's reading ~1V when throttle closed and ~4V when throttle open. Not sure what the voltages are supposed to be but that looked sensible at least. The voltage changes smoothly over the range too, no jumps or spikes.

I might give the TPS ...

SOLVED (FINGERS CROSSED):

First an update on the signals I am seeing on the lock-up clutch solenoid [1I] and the line pressure solenoid [1E] - these outputs *do* appear to be PWM modulated, now I've seen the unit working correctly with the scope connected I can see the duty cycle of the 50Hz output ...

Thanks for your replies.

I discounted the TPS as it's changing at what appear to be the correct points (as it was when it was working) in gears 1-2-3 and it kicks down too. I'll put a scope on the TPS and see what the signal looks like and how clean it is.

Regarding the solenoid outputs, I've ...

Hi everyone, this is my first post - unfortunately it’s asking about a gearbox (BM715) issue I’m having with my 1999 2.5 diesel. I’ve looked around at posts on related topics but can’t find an answer to exactly what I’m seeing. I’ve tried to check and test as many aspects of the system as I can ...