mk 7 no signal from bcm pcm help needed

[elchpo]

hi all, new to site and looking for help.
mk7 transit, running then cut out .. traced problem to earth by drivers seat.. redone earth bolt cleaned up metal etc, all ok. seam to be from water ingress from windscreen bond,
been fine for two weeks, now same problem , thought id sealed screen but still a little water so going to get redone by windscreen fitter..

so problem i have is no lights on cluster just the digital mileage, and light when door open..
have checked all earths and all good , all fuses and relays are good to..

no comms between bcm and pcm.. on c3 plug on bcm noy lead pins 11 and 12 showing 11v not 2.5 as should.. i guess theres water in canbus or something but unsure where to look now. van is a 2.4 twin batt ex mini bus..

thanks in advance for any help.. been trying to try find canbus routes etc but no luck..

[elchpo]

please someone point me what to try next

[knobby1]

please someone point me what to try next

Main fuse at rear of battery box ok..??

Earths on inner left wing behind the PCM ok.??..They often rust badly. There's a multitude of earths on the Transits, inside under the dash and all around the engine bay and on bodywork.

Screenshot 2026-06-08 065831.png

Lord Knobrot (Smithy)

[elchpo]

please someone point me what to try next

Main fuse at rear of battery box ok..??

Earths on inner left wing behind the PCM ok.??..They often rust badly. There's a multitude of earths on the Transits, inside under the dash and all around the engine bay and on bodywork.

Screenshot 2026-06-08 065831.png

Lord Knobrot (Smithy)

allearths left inner wing good van only done 44k. and i pinned them from middle pplug on pcm b a4.
you earths on drivers batt to floor as that was the cause las time. on my top gone can talk to bcm but not bcm to pcm all fuses and relay checked all ok'
inner earth to left of bcm in wing ok
not on under dash? was thinking maybe canbus?

toof off plugs on pcm and all earths are fine. cluster module is fine use top don.

c
but there is no cluster lights. only digialmilage in that square sceen. havent checked rear of rear of van earths unsure where they are

[elchpo]

no signs of water inside on left where bcm is.
how water is getting driver side top screen hence i found the issue of bad earh at driver seat fixed all ok for three weeks .. then loading van one day whilst it was running it just cut out..no cluster lights.. remot locking works windows etc radio.

[elchpo]

these are the codesshowing
b10a2;35 oa crash input
u0151;00-0a
uo100;00-0a
(pcm)au0100;87-2b
(pcm)a
cocact cleaned everthing

[elchpo]

sorry for al questions it my camper and need to get out.

where are earths under dash and rear / thanks again

[tranmx2]

put this into g search 10a2;35 oa dtc

What is the error code B10A2?
The recurring crash input fault B10A2:00-2E disables starting, often linked to incorrect battery or wiring issues. The P0420 code indicates catalyst efficiency problems but does not prevent starting.23 Oct 2022

AI answer included this: If this fault is active, many vehicles will enter a fail-safe state that delays or completely disables the starter motor and fuel injection to ensure safety following a detected collision or sensor fault.

At the bottom you can ask AI a question - AI will answer a question relative to the answer already given.

Better if you show the yr of the vehicle.

lead pins 11 and 12 showing 11v not 2.5 as should -- could be a wiring issue - 12 V wire touching the 2.5V wire.

How come it is a 2.5 v wire? Supposed to be 12 V and 5 V any reading of the V is dependant on the resistance(s) in/on the wire.
Are you reading/looking at the pin numbers the correct way around?

[elchpo]

yeah had wrong pins, wrong plug, thanks going to look at crash senor wiring and try see where crash sensor is. its strange as only water ingress drivers side..
passenger side dry bcm to fire wall dry. van only done 45k so earths etc good no rust anywhere.
thanks for help. just got to keep looking..

do you think fuse box wiring loom replacement would help ?
my van in late 2006 2.4 exra long wheelbase exminibus now camper

[tranmx2]

thanks going to look at crash senor wiring and try see where crash sensor is. Don't know where the crash sensor is - there could be a fuel cut off valve to the left of the passenger side where the fuse box is. It is yellow.

Inertia switch fuel cut off.JPG

Could be different on your vehicle.
Others on the forum are familiar with the 2.4 2006 Mk 7 Transit.
Often see posts re' campers where a fitting screw has been found to have shorted some wiring.
Initially the screw touches the wire's insulation. Years later due to vibration for eg the insulation wears and the wire then touches the metal screw.
Some good youtube vids to watch: Pine Hollow Diagnostics, Diagnosdan, ORiley DPF, South Maine Auto, RMS diagnostics who has - sometimes - on a big screen some wiring diags.

Better to sort out/solve one problem then do the next. The parts cannon does not always work and does not always give the answer as to why it went wrong. Can be an expensive way to find a pos' temporary fix.
AI I have found to be good so far. Often the info is mixed - likely due to me asking the wrong question about the wrong thing. I find it better to put in all the relevant info'.

The last time AI was asked for info' the following was put in: 2012 transit BCM as buIlt from motorcraft to laptop laptop via forscan ELM 327 FTDI extended license to van BCMii selected - success - not written. I did not ask the question: How to do it. The answer from AI told me how to write the data to the van BCM. It won't make any sense to you - the example is to show the type of info' that is needed.