I finally got around to checking the connection to the Haydn coolant alarm.
It has switched power right to the unit but does nothing. Makes no sound when power is switched to it.
So, it must be broken

(It is supposed to show signs of life when power is applied, yes? Coolant or not?)

I'm doubting myself and rightly so.
Thank you both.
I may well have used the nearest bit of chassis to check the 12V.
When I'm next able to, I will check the 0V connection (although it did feel solid enough, I recall) and furthermore do as Gilly said.
Have a lovely evening, all.

Eh? It's a low coolant alarm; it only lights up & sounds for a few seconds (test) when key is first turned in the ignition and then again (of course) when the coolant drops below that screw in the header tank. They are bulletproof - likely just a bad earth or broken wire.


Hello.
Mine does ...

Hi, I have a coolant alarm fitted in my Bongo. The alarm was in it when I got the Bongo about a year ago.
I take it if the alarm is not working then it's just plain broken?
It has 12V/0V going to it and it's connected to a screw in the coolant tank. It shows no signs of life...
IMG_20250426 ...

Hello.

Should you change this manual download page, do you think?
https://igmaynard.co.uk/wiring/

I sent you my VIN number as you requested but received no files.
I think it's a little wrong to ask for people's post codes and VIN numbers and not help them with diagrams.
Honestly, it sounds a bit ...

The connections for the diesel are on the diagram below, the ringed numbers relate to the ECU pin numbers and the colour codes are against each wire;
Screenshot 2025-02-08 162129.jpg

the colour codes for the wires are;
Screenshot 2025-02-08 162129.jpg


I have no idea which node(s) will tell me ...

A meter isn't going to be of any use its a pulsed system and its the % of the duty cycle that determines the position, its pulsed at 50Hz and the On period compared to the Off period that determines the selection;
Screenshot 2025-02-08 150819.jpg


I have a scope too. I just have no idea where ...

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 ...

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/viewtopic.php?p=699326#p699326 Alacrity is our gearbox specialist!!


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

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/viewtopic.php?p=699326#p699326 Alacrity is our gearbox specialist!!


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

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 ...

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 ...

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 ...

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.

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..