Ford transit 21 plate draining battery whilst locked

[Transittony182]

Hello,

I have a 21 plate transit MWB.

Originally when I locked the van the full beams would come on after around 10 mins and completely drain the battery overnight.
I’ve heard of some water ingress issues with the BCM so I took it to a local garage.
They said the BCM was okay and the problem was caused by a faulty head light control switch which had coffee stains and dried sugar on it… I’m guessing from people putting drinks in the drinks holder and it spilling.

Since this replacement the headlights no longer come on 10mins after locking. But still slowly over 1-2 days if not driven the battery still goes completely flat.

Just wanted to see if anyone has a fix or a similar issue before I take it to Ford.

Thanks in advance for any advice.

Josh

[dumper]

Its possible it’s original battery and ready for replacement if single battery if twin battery one is gone but I wouldn’t replace only one battery seen it many times replacing only one can drag the new one down and kill it but with the Ford system disconnecting then when engine is off you may get away with charging the bad one
But you need to get them drop tested with heavy duty battery tester

[Altransit]

As above, if the battery has been drained to zero a few times, as well as being 5 years old, It's possibly past it's best, and needs replacing.

If you're convinced that it's random current drain, you'll need to disconnect the battery and connect an inline ammeter to see how much current is draining, and over what period.

[Transittony182]

Thank you for advice.
There was a new battery fitted when the fault started, and another fitted yesterday to see if this was a faulty battery but the problem still happens.

Thank you for all advice so far.

[metalworker0]

battery live disconnected .. put amp meter between live lead and battery post .. measure amps .. start taking fuses out and relays .. until l the drain equals less than 0.02 to 0.05 amps

its probably a relay that is sticking

average drain after all systems go to sleep is 0.02 to 0.05 amps.

your vehicles handbook/ owners manual has the location of the fuses and relays in it .

can also be located online .. at the ford site for free .. you have to know build date.. not purchase year

all the best.mark

[dumper]

A common problem back before smart charging was the diode pack in the alternator falling and draining the battery over night you could try disconnecting it overnight to see if that’s the problem