Rear cabin lights stay on all the time

[Hart_graham]

Thanks for that. Working round the showers today.
Decided to concentrate on the brake light fault - have no access to code reader today anyway.
I have the haynes manual wiring diag in front of me and looking at the ext lighting, 2.2l models
It shows the 4 contact switch as follows. contact 1 & 2 normally open and contact 3 & 4 normally closed.
1 -ye/rd
2 vt/wh
3 bn/gn
4 bk/gy
When I look at the plug on the van I see
1 ye/rd
2 bn/gn
3 bk/gr
4 vt/wh
When I test for 12v with ign on I get 12v on pin3 of the plug(br/gn). ? and haynes diag shows as coming from the power control module.
When I test the sw I find 2 - 3 normally open and 1 -4 normally closed. Switch works fine.
So I conclude that the plug wiring in the van must be good since its always been like that and...
The haynes manual wiring diagram must be incorrect.
Or/And I must have the wrong switch. Haynes manual clearly shows a different wiring for the 2.0l model.
Question - where is the power control module?
Oh and with the ignition on the output at the pin with the br/gn wire which I have assumed is pin3 (depending on whether you number from L to R or R to L) is 11.4v. If I start the engine it 13.6v Battery voltage is 12.6v and 13.9 with engine running.
I hope you can make sense of all this. I shall ring the motor factor place and see if there is a different switch for the 2.0l model.
Thanks again for your help.

[Hart_graham]

Doh
just realised that the PCM is the powertrain module.

[Altransit]

Doh
just realised that the PCM is the powertrain module.

That's right, lighting control is via the body control module (BCM)

[Hart_graham]

Checked the voltage on the engine bay fuse panel - as PCM gets its power from there.
Voltage at jump start post was 12.46, Voltage at the PCM fuse was 11.4,
Put all lights on for 10 mins to load test battery and watched the voltage drop to about 11.6 within 5 minutes.
Took out drivers seat and both batteries. Tested both batteries with battery tester, Front battery failed test with a bad cell. Rear battery good. Both original Ford batteries dated Nov 2014.
Replaced both batteries with new and refitted seat. Started first touch but still 'Service Engine now' and no brake lights. After depressing brake pedal a couple of times the 'skid' light comes up on the dash.
Tried w/o success to reset battery monitor - 5 x headlight flash + 3 times brake pedal.
Checked the voltage at PCM fuses and its now 12.4v.
Will put diagnostics on it tomorrow and then jump out the top floor window

[Frag]

Manual battery monitor reset is 5 times on rear fog,3 times hazards,if successful the battery / charge symbol in cluster should flash.
(Note in case anyone else in future reads this,DOES NOT work for 2.0 eco blue/panther variants)

The fact the esp/traction light comes on after pressing brakes again suggests you have a correlation issue between the 2 circuits of brake pedal switch.
I’ll post my wiring diagram info for brake switch later when I get chance..

[Hart_graham]

Thanks for that. BMS now reset
Still have Service Engine now and traction control light and no brake lights.
Look forward to the wiring diags

[Frag]

Circuit 1
Fuse 18,10Amp,BCM (should be live at all times)
Yellow/red feeds pin 1 of the brake light switch.
This is normally open
When closed / pedal depressed,feeds pin 4 which is violet/white.
This then splices and feeds the BCM and the PCM.
(The bcm will then switch the brake lights)

Circuit 2
Brown/green from PCM to pin 2 brake lamp switch.
This is normally closed,so will go open circuit when brake pedal pressed.
feeds pin 3 at switch and is a black and grey wire which is direct to earth.

[Hart_graham]

Thanks for that, will compare to mine/test. Really appreciate your help.

[Hart_graham]

Ok so started with my multimeter on the plug from the brake pedal swicth. I should perhaps explain that the pin numbers mean nothing as they don't seem to run in any sensible order but the colours of the wires correalate to the switch (NO and NC contacts. No 12v on one circuit and only .5v on the second.
So took the trim off beneath the steering column to gain access to the BCM and stated to disconnect the plugs one by one. The blue one fine but the left hand brown one showed clear evidence of moisture ingress.
Decided to take the BCM out and then the damage was clearly evident. See pics below

IMG_20221106_125336.jpg

One pin missing and second pin almost gone. Spent a little time splitting the BCM apart. See below

IMG_20221106_134849.jpg

Next couple of hours spent removing damaged pins from the board and replacing them.
Cleaned up the rest of the pins before reassembling board into the BCM and reinstalling all the fuses. Put it back in the van and powered up after checking voltage at the BPP plug
Fired up the van and hey presto, no faults and the brake lights work.
lasrge glass of wine called for.
RESULT
Thanks for all your help.

[Frag]

5v is correct for the pcm bp circuit,
I don’t need to tell you why you didn’t have the 12v feed,looking at those pics
Glad it’s sorted,will almost certainly explain some of the other electrical ‘gremlins’ you’ve been experiencing.

Maybe worth leak testing around the windscreen,and making sure the roof rack/or it’s holes/ bungs are sealed.

[Hart_graham]

No evidence behind the dash of any leaks anywhere. My guess is that at some point someone using the storage bin over the steering wheel as a food tray tipped a drink over. Meant to look at the date stamp on the screen to see if it has been replaced. Just that one sign of damage at the lowest point on that one plug. Looked like it had been there a long time - cola or similar is corrosive, to eat away the pins like that. The pcb was absolutely fine - like new.
Just glad I finally found something and that the pcb repair worked.

[Hart_graham]

So back to one of the original faults - the internal rear lights staying on.
The power comes from the battery and is controlled by the BCM with the rear door catch also switching them off when the tailgate closes. The tailgate switch/sensor appears to be faulty. Checked the price of a new latch mechanism and this coupled with the faff of having to take out the door trim (which also means taking out the rear curtain and rails) had me searching for an alternative solution.
Disconnected the return to the BCM from each light and fitted a miniature switch into the left hand light (already had suitable switch). One side of the switch to both lights (-ve) and the other side connected to an earth point drilled next to light fitting. Job done. Only downside is that the light no longer comes on when you open a door. Light still goes out with the timer (if you leave it switched on).

So now I can take the van down to Cornwall next week storm watching