Hello guys, just to say hello to you all and while im here see if i can bend your ears and ask if there has been a problem with no rear number plate lights working on a Doblo tailgate.... after all my checking for good earths and such i found or possibly found that there is no live at the plug ends ive also noticed the interior boot light is also not working, does this run off the same wiring. Cheers in advance for any advice.

No one got any idea then on this forum.? :bang:

I think possibly your vehicle has multiplex wiring (does the dash tell you if a door is open or a bulb has gone?).

In which case, it is entirely possible the relay responsible for that particular circuit is either malfunctioning or the BCM is on the blink.

The BCM is Body Control Module and is a computer controller that decides which circuit gets which signal. Multiplex is great when it works, but when things go wrong, it can be a pain to figure it out.

Back in the early days, Peugeot's 406 or 407 (I forget which) had multiplex. A good few suffered a dashboard malfunction and it was a bugger to find.

Eventually, it was tracked down to the boot mounted CD player. It was mounted low down and if the boot suffered water ingress, the CD player would fill up & short out the dash.

Imagine, something 6 feet away causing problems!

Anyway, it is possible something else is causing the problem and affecting other circuits like the number plate lamps & interior light.....

Only real way to find the cause is have a look through the BCM for stored fault codes.

Bit of a guess but I would think the boot light is separate to the number plate lighting as they would come on and off at different times. The front sidelight and the back taillights however are probably on the same circuit as the number plate lighting so do those come on? Check the contacts/harness to the tailgate.

Thanks for your replies fellas, and i have thought myself that they would be on same
circuit as sidelights but just noticed that my reversing lights also not working ?
Could this be from the contacts/harness from tailgate ? :bang:

The reverse lights wiring will be in the harness to all the rear lamps, but the number plate lamps wiring then goes through a rubber trunk to the rear door.

It is entirely possible the wiring has split inside and could be affecting the multiplex BCM which in turn has shut down the + feed to that side of the circuit.

Multiplex is clever in that one wire can carry several signals, so it is a possibility that there is a broken wire in the circuit.

thanks andoo, i will have an investigate when i get a bit of time in the week and
will get back on here and let you know what i find.
not enough hours in a day !!

Managed to have a quick investigate today and found no breaks in wiring in the rubber elbow to tailgate, i did disconect the plug in the boot area where the loom runs and put a tester pen in the ( live side coming toward the tailgate ) and i did notice on one of the feeds ( green/black which are the number plate wires ) made a clicking noise from the front of car which i presume is a relay, i dont know which one as it does not tell me in the book, could this be the problm or are we going to go back to this multiplex job.
many thanks on this matter as all info is moucho appreciated, :bang:

:idea: no ideas coming through, been at it again but getting nowhere fast.

Sorry Dobbo, been busy....

When you say it made a clicking noise (which will be a relay) in what context?

Did it click when you connected it, tested it with the tester pen on it or did you apply a voltage to it via the pen?

I wonder if it's just a bad connection?!?!

I took my XK8 out of hibernation after two years and a headlamp bulb was out. Turns out it was the earth at the lamp.

Hi ya no probs andoo, just banging me head mate, no voltage applied when tester pen used but noise was a (clicking that a relay does or should i say sound of a very fast indicater flicker) if you know what i meen. could well be a bad earth as yet another problem stems and that is the central locking is now not working either :bang:
Just keeps getting better and better. anyway thanks for any advice cos its just about doing me in now.

What's the battery voltage like? Ignition off what is the actual reading?

Anything around 11.5v is ok, but not good. 12.3v upwards is good.

Start engine and see what the output is then. Anything around 13.1v up is fine up to 14.8v. Anything over is bad.

I would be tempted to clean the earth from battery, body and gearbox, then check the smaller earth points at various points in the body & under the bonnet.

I think there are a few in the load area, but behind the speaker pods.

Thanks andoo will give that a go when my head clears, many thanks for your help and will get back here when problem is solved (hopes) and let you know the outcome,
thanks again, ciao 4 now. :spin:

Hi again fellas and lassies if there are some looking here, Now i know its been four weeks or so since i was getting confused about my doblos number plate lights and did say i would have another investigate when i had more time, Guess what. i havnt had much of that so i am wondering know that i have been away from it and now going back to it all fresh and such is there any person or somewhere where i can get hold of a wiring diagram for the plate lights as ive got to try and find where these are earthed and i can then try again at this problem, many thanks guys for all the advice so far.
:idea:

.....Should i take these non replys as a no then for wiring diagrams.....

Dobbo52 said:

.....Should i take these non replys as a no then for wiring diagrams.....

Click to expand...

if you stick to the Doblo section , you may have more people looking / able to answer..,

Charlie

yeah nice one, didnt give it a thought really as i was on here as a new member,
thanks for the nudge charlie.

Re the wiring diagrams - not sure exactly where the link is but I believe in 'Guides' in the blue tool bar at the top of the home page on here. Click on there and I'm sure there's a downloads section which will list the Manuals that can be downloaded. You might get lucky and find a wiring diagram in one of those manuals.