This is a weird one. I have recently bought a 2011 s max tdci 2.0 titanium which has 104k on the clock. 
At seemingly random times it doesn’t start and then displays a power steering fault on the dash. I can then give it a minute and most of the time it will start. 
The guy who sold it to me is helping to fix it and has a tamed mechanic but thought I would ask the hive mind here for advice. 
When the mechanic plugged in the diagnostics it was inconclusive. We then measured the voltage to the starter motor, this would fluctuate between 14v and 0v. Changed starter motor relays but we then ran out of time.  
Fault appeared again a week later. Since then they have swapped the battery out and changed the key fob batteries in both keys. Thought it was the immobiliser and key fobs but yesterday it did it again with what I thought was the “good” key. 
Any one else come across this before? 
I may be clutching at straws but the days when it has regularly failed to start, the night has been icy. Is water ingress and thawing ice a common problem on s max looms and contacts? I am pretty sure it isn’t the power steering as that feels fine and has no leaks. 
Is it worth pursuing the power steering fault though, does that point towards a specific module or point to the EMS being dodgy? 
It goes back in next Sunday so any advice would be greatly appreciated. We got it to fit in the three kids we now have (thank you lock down!) and my wife is now pretty jumpy about going anywhere in it! 

Thanks chaps,

Dan 
 

Remove the main chassis earth lead between the battery negative terminal and the car body. Clean the rust / dirt / paint off the bodywork and clean the terminals on the main earth.

The power steering fault is almost certainly caused by low voltage.

 

Thanks Unofix, that makes a lot of sense and would explain the voltage disparity to the starter motor. I will let you know how I get on. 

Dan, I have a 2006 2.0Tdci Smax and very similarly, have a steering fault information light that comes up a lot and the car will sometimes start as soon as you turn the key, most times it turns 3 or 4 times. But every few days it will take numerous attempts, seemingly getting closer to starting but not quite, but eventually it will start. There appears to be no rhyme or reason to when it will strike. I will also try as suggested.

I have also tried 40minute drives at 3500 revs up and down a dual carriageway as my normal commute is now only just over 1 mile to work. Have to admit very nearly doing a full on Basil Faulty, it drives me nuts. Lets hope it works for both of us!

Ian

On 3/2/2022 at 8:51 PM, owner-ian said:

Dan, I have a 2006 2.0Tdci Smax and very similarly, have a steering fault information light that comes up a lot and the car will sometimes start as soon as you turn the key, most times it turns 3 or 4 times. But every few days it will take numerous attempts, seemingly getting closer to starting but not quite, but eventually it will start. There appears to be no rhyme or reason to when it will strike. I will also try as suggested.

I have also tried 40minute drives at 3500 revs up and down a dual carriageway as my normal commute is now only just over 1 mile to work. Have to admit very nearly doing a full on Basil Faulty, it drives me nuts. Lets hope it works for both of us!

Ian

Soooo, update on where we got to with my s max. Mechanic did a drop test on the battery (to check for voltage drop to ground) and was all functioning correctly. Ran some diagnostics and it finally settled on a faulty ignition relay (which would also explain the power steering low volts fault). Replaced the relay and it’s started first time for a week now. Will let you know How I get on, hopefully this has fixed it, although I am prepared for it to turn up again! 
 

Dan 

Any chance you could post a photo showing the location of the ignition relay. Tried phoning my local ford dealer to buy one, but they said I need to get a number off it so they can order the right one even though they had the registration number, not helpful. Spoke to an independent garage who spoke to ford and they wouldn't even tell him it's location. Don't think they are that expensive so it is worth a try to replace it to see if it cures my cars problem. Just have to find the little bugger first! I can post a photo of the engine bay fuse box, or wherever it should be, so you can just highlight it if it helps.

Many thanks for any help