Diagnosing auto 4th gear issue

[Sharbee22]

I'm trying to diagnose why my auto box will rarely go into 4th.
For Friendee 2.5 V6 diesel auto 1998
Which wire(s) should I probe onto to see if 4th gear is being commanded?
Physically where the wire is and colour would be helpful too please

[g8dhe]

You need to refer to the electrical diagrams which require use of Flash at http://www.g8dhe.net/bwm/ see the discussion on the wiring diagrams on this forum for details of browsers that still support Flash ( https://igmaynard.co.uk/bongo/forum/vie ... 68#p723668 ). There is also the gearbox manual available http://www.g8dhe.net/bongo_images/Gearbox/RC4AEL.pdf
A small image of the relevant page below;

[Sharbee22]

Thank you

[Sharbee22]

Hi.
Is that gearbox PDF manual for my vehicle? That looks like a later model 'box...
The PDF manual refers to shift solenoids A/B/C/F but the wiring diagram snip you kindly posted only has shift solenoids A/B.
I'm very confused..

[g8dhe]

The diagram shows a total of 5 solenoids A/B/D/F & TCC, never needed to assign each of the there functions see page 05-13Y-3 where it refers to ABDF&TCC and then the table on the next page where it refers to A/B/C/F&TCC

[Sharbee22]

Can anyone tell me which wire(s) on my van should I probe onto to see if 4th gear is being commanded?
Physically where the wire is and the colour(s) would be really helpful please.
Thank you.

[Sharbee22]

The diagram shows a total of 5 solenoids A/B/D/F & TCC, never needed to assign each of the there functions see page 05-13Y-3 where it refers to ABDF&TCC and then the table on the next page where it refers to A/B/C/F&TCC

In the diagram I can only find a lot of Japanese-labelled solenoids, only two of which translate to shift solenoids (A and B). The other solenoids (Overrun/Lock-up/Line Pressure) are not referenced in the PDF (RC4AEL.pdf)

Ha Translated.

Is RC4AEL.pdf for my vehicle? It seems to be a newer gearbox than my camper... or does it work the same way?

[g8dhe]

Which gearbox do you have on your vehicle ?
See the table on 5-13Y-4 which shows which solenoids are operated for each gear selection, its not a simple one wire one gear mechanism, its a binary selection from the control solenoids and the internal pressure switches;

[Sharbee22]

Which gearbox do you have on your vehicle ?
See the table on 5-13Y-4 which shows which solenoids are operated for each gear selection, its not a simple one wire one gear mechanism, its a binary selection from the control solenoids and the internal pressure switches;
Screenshot 2025-02-08 100539.jpg

I don't know what gear box it is, sorry. Are there several for mine, do you think, based on the following:
Friendee 2.5 V6 diesel auto 1998 (S Reg)

[g8dhe]

I'm Confused ? the V6 is a petrol engine not a diesel ? The diesel is a 4 cylinder engine not a V6!

Try looking on the gearbox itself, it has a tag with the serial number on, the precise gearbox varies a lot with each engine as the speed ranges vary the RC4A-EL is the generic box description.

[g8dhe]

Just a thought you are letting the gearbox warmup as it won't select 4th gear until its at a suitable temperature see here https://igmaynard.co.uk/bongo/forum/vie ... 26#p699326 Alacrity is our gearbox specialist!!

[Sharbee22]

I'm Confused ? the V6 is a petrol engine not a diesel ? The diesel is a 4 cylinder engine not a V6!

Try looking on the gearbox itself, it has a tag with the serial number on, the precise gearbox varies a lot with each engine as the speed ranges vary the RC4A-EL is the generic box description.
Gearbox_tag_location.jpg

Sorry, I must be mistaken... It mustn't be V6.
I'm not able to get to the gearbox tag any time soon...

What I don't understand is how the wiring diagram snip you posted (Japanese) only shows 2 shift solenoids (A and B) but the PDF has C/D and F!
How come the wiring diagram doesn't show C/D and F?
Also, why does the PDF call it C on one page and D on another, is that a typo on one page, do you think?

[Sharbee22]

Just a thought you are letting the gearbox warmup as it won't select 4th gear until its at a suitable temperature see here https://igmaynard.co.uk/bongo/forum/vie ... 26#p699326 Alacrity is our gearbox specialist!!

Oh, yes, it's warming up OK. On a full motorway run it rarely will change up to 4th

[Sharbee22]

Just a thought you are letting the gearbox warmup as it won't select 4th gear until its at a suitable temperature see here https://igmaynard.co.uk/bongo/forum/vie ... 26#p699326 Alacrity is our gearbox specialist!!

Oh, yes, it's warming up OK. On a full motorway run it rarely will change up to 4th

Although, the temperature gauge on the dash seems to not be working... could that impact I wonder...

[g8dhe]

The translations and naming's seem to vary a lot depends I suspect on the sources of information if you look up in the gearbox manual you will see that a lot of the selections is on the basis of the two main gear choices and then the various epicyclic combinations give the other gear ratios.

The display temperature gauge has no other input to any of the vehicle systems its only for the display alone if you look at the diagrams. There is another temperature sensor (2-pin types) that measures the temperature feeding the ECU. The gearbox has its own sensors internally feeding into the gearbox electronic controls.

I presume you have checked the state of the ATF and its not dirty or burnt ?