I completely forgot to put in a post on this after finding the problem in afew hours and then fixing it. This is bit long winded, but it is just to take you through the background to the story.

My Brother in law and sister own a 2012 ford Focus Mk 3 1.6 Titanium model. Two years ago when I was speaking to her she told me she was having a problem with the Focus battery going flat overnight and not being able to start the car in the morning. She had taken the car to an auto electrician,  a Ford dealer two independent garages to fix the battery draining issues. The auto electrian put in a new battery as he could find nothing wrong  and would not deal with it anymore as he hadnt time Ford dealer would not halp as it was an import from the UK. Two independent garages gave up on it and told them to disconnect the battery every night. The reason I believed  that they could not diagnose the problem was that they were disconnecting the battery to check the current draw was this was resetting the electronics and the problem would disappear. I had come across this previously in my time in Telecommunication and  IT dealing with electronic faults.  I told them to disconnect the battery for 5 minutes and then leave it overnight to see if it would drain and it did not. They left it for a week no problem battery was fine . I then asked them to not lock it over night to rule out the locking system and the alarm and it made no difference. That ruled those two items out. I eventually managed to get the time to call to them armed with one item a digital clamp meter suitable for DC. Put a small piece of plastic into the bonnet micro switch to allow us keep the bonnet open and simulate it being closed. Locked the car put the clamp meter on the negative lead and the current being drawn was 2 amps. Disconnected the battery and reconnected it after a minute. Locked the car and the clamp meter showed .03 amps. With the car unlocked and after 30 minutes it was still .03amps. Start the car turn it off and the drain was 2 amps. now was the time to start pulling fuses. Eventually we discovered that after pulling the Audio fuse the current would drop to .03amps. I made up a  connection to fit the fuse put an inline fuse in it and a switch. Until I returned they just had to turn the switch off each night. I came home downloade the wiring diagram and went through the audio section. The only item that had a direct connection to the battery and was not turned off by the ignition switch was the blue tooth module. they called to me when I return ed and we dismantled the dash to get at the bluetooth module. Disconnected it and checked with the clampmeter. .03amps. the bluetooth module was causing the problem. we left it disconnected, pput the dash back together and got a second hand module with a 30 day warranty. It has been fine ever since.

A clampmeter is worth its weight in gold trying to trace these faults in newer cars packed with electronics. Hope this saves time for others. 

The clampmeter I used is a Mini Clampmeter Tenma T2-14405 and are relatively cheap less than €100

Pleased you sorted it.

As many on here will tell you, battery drain problems on the Focus Mk3 is nearly always the Bluetooth module.

3 hours ago, unofix said:

Pleased you sorted it.

As many on here will tell you, battery drain problems on the Focus Mk3 is nearly always the Bluetooth module.

Interesting, but what intrigued me most was that when I said my Brother in law to suggest the clamp meter option instead or disconnecting the battery this to the last garage he went tthe mechanic totally ignored it. He met the mechanic recently and he asked him how the car was going? Brother in law said running perfectly since he got the battery issue fixed, but never told him who did or how it was fixed.

 

1 hour ago, Unfazed said:

he went the mechanic totally ignored it

This is a very common problem. Its not the fault of the Mechanic, who as the name suggests is trained and is probably time severed to deal with the mechanics of vehicles. Even a good well experienced mechanic will only have limited abilities to fault find and diagnose electrical/electronic faults on any car built in the last thirty years.

This is why good dealerships have Auto-Electricians who specialise in the electrics of the vehicle. Granted they are not very good at changing piston rings, or even repairing a gearbox, but they let the mechanic deal with those 🤣