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Large MPVs -- Ford Galaxy / VW Sharan / SEAT Alhambra: => Mk3 Ford Galaxy / Ford S-Max => Topic started by: ihopethiswillfi on February 16, 2019, 02:37:35 PM

Title: S-max MK1 electronics switching on and off like a christmas tree
Post by: ihopethiswillfi on February 16, 2019, 02:37:35 PM
Hi all

S-max MK1 2014
2.0 TDCI 140hp, manual 6 gears
Convers+, xenon, navi plus, electrically foldable side mirrors and electrically adjustable front seats.

Certain components (all lights, side windows, screenwipers, airco) are only receiving power intermittently at a frequency of about 1Hz.
The dashboard is also going crazy e.g. fuel sensor suddenly not detecting fuel; the clock can suddenly jump a few hours into the future and then it returns to the correct time after a few seconds.

What I've tried:
- official Ford dealer visit.  Car stayed there for a week, of course the problem suddenly didn't occur while it was there, so they just sent me home again after taking my money.
- an independent mechanic locally referred to as a "Ford expert" didn't want to even look at it cause he had no clue at all.
- many hours of searching the web for similar problems
- removed and checked battery (what an enjoyable job on this car!).  This can't be the issue as the problem even occurs right after charging the battery.
- checked all fuses.

Can anybody point me into the right direction?  I'm getting a little desperate after a month.  I can't really use the car on public roads like this.

Any help greatly appreciated!


Title: Re: S-max MK1 electronics switching on and off like a christmas tree
Post by: johnnyroper on February 16, 2019, 06:38:12 PM
My first instinct is either an earthing issue or BCM failure,has any work been done to the car prior to this fault occurring?
Title: Re: S-max MK1 electronics switching on and off like a christmas tree
Post by: gregers on February 16, 2019, 09:01:30 PM
probably a shot in the dark,but have you tried checking the wires in all doors and rear hatch,mine went a tad haywire and i found some wires broken in the rear hatch which were shorting things out.yes even these cars suffer from tight wires bracking.
Title: Re: S-max MK1 electronics switching on and off like a christmas tree
Post by: ihopethiswillfi on February 17, 2019, 08:53:09 AM
Ah sorry, I forgot to mention:
The car worked fine for months after we bought it, then the fault appeared first time in the middle of a drive into the city.  Then after locking the car for 10 minutes the problem was gone.  Then after a few days I started the car and the problem was there as soon as I switched on the ignition and I couldn't make it disappear by locking the car even for the night. 

So sometimes it's there, sometimes it isn't, and I haven't found how to reproduce it. 

I've cleaned the earths in the front left of the car, there are 7 close to each other bolted to a piece of chassis between the air filter and the front left light.  Although that wasn't really needed, they were in excellent condition. 

I've done a quick but not extensive check of the wires in the rear hatch, but not the doors.

Guess I'll go and check some more earths / wires.

Is there a wiring diagram available for the electronics?  I haven't been able to find any.
Title: Re: S-max MK1 electronics switching on and off like a christmas tree
Post by: Mirez on February 17, 2019, 09:56:01 AM
IMO thats far to controlled to be an earth or wiring fault [in the true sense], instead I would say the BCM is powering down and back up. My first thoughts are load shedding but I would be very surprised if the BCM has the authority to load shed the headlights, even with the engine off. Therefore, assuming the BCM itself isn't the cause, I suspect its recycling in response to an overload situation. However:

1) A battery charged overnight isn't a guarantee its good, I notice you say you checked the terminal voltage but what was the actual voltage? To rule the battery out you need to measure the terminals post charge, when charging, after charging and 12 hours after standing - all while its out of the car.

2) If I were diagnosing this, I would be ruling circuits in to narrow down the location. IE Since you have so many failures, what circuits are NOT being effected? The BCM controls 95% of the car, so its a good start point unless you find some unaffected circuits. Also, please confirm the headlights are actually doing the rhythmic on/off and its not just being reported that they are. You should also try global unlocking the car to see how the windows behave when the ignition isn't on.

3) Finally, there will be an ignition relay in the engine bay that powers up and should stay energised. Your next step should be to identify which relays are cycling [clicking], I think you say there is one in the back, in the dash box and one in the engine bay? What relays are they and what circuits do they control?