Keyless start. Clutch must be down for engine to fire. 

So... haven't got any further with this. Realised that I didn't mention that if I forget to disable Stop Start and it activates, the engine fails (usually) to fire when I depress the clutch, which presumably rules out the start button as a cause? Also, the start button always works to switch the ignition on and off. 

Further internet digging reveals an infuriating number of unresolved posts about similar issues, across many different forums. One thing that was mentioned as a suspect is the Transmission Control Module, but I'm unsure if manual cars even have one of these?

Is the clutch switch easy to access and replace? I might try that next if it is. 

Thanks.

If the car doesn't detect a clutch-down signal, it should ask you to press the brake instead.  You can test the clutch switches on Forscan using live data. 

Manuals do not have a TCM.  There is a neutral position switch on the gearbox which could be faulty, that is wired to the engine ECU (PCM).  Again that can probably be tested on Forscan live data, though I haven't seen it done on a car of this age.

I'm wondering if it's the starter motor tbh.  If you're in a position to swap it yourself to save on labour costs, it might be worth trying a good used replacement to see if that makes any difference.

3 hours ago, TomsFocus said:

If the car doesn't detect a clutch-down signal, it should ask you to press the brake instead.  You can test the clutch switches on Forscan using live data. 

Manuals do not have a TCM.  There is a neutral position switch on the gearbox which could be faulty, that is wired to the engine ECU (PCM).  Again that can probably be tested on Forscan live data, though I haven't seen it done on a car of this age.

I'm wondering if it's the starter motor tbh.  If you're in a position to swap it yourself to save on labour costs, it might be worth trying a good used replacement to see if that makes any difference.

Thanks for the reply. Interesting what you say about the "press brake" message. I see this very occasionally, and have never understood why, as pressing the brake is not part of the starting procedure. I also occasionally see the "depress clutch to start" which makes more sense, but is also not something I can repeat at will. Normally pressing the start button a second time without depressing the clutch simply switches off the ignition. I will have to re-borrow the windows laptop at check the live data on Forscan. 

How easy is changing the starter motor? Doable with axle stands, or is a lift needed?

4 hours ago, ElCani said:

Thanks for the reply. Interesting what you say about the "press brake" message. I see this very occasionally, and have never understood why, as pressing the brake is not part of the starting procedure. I also occasionally see the "depress clutch to start" which makes more sense, but is also not something I can repeat at will. Normally pressing the start button a second time without depressing the clutch simply switches off the ignition. I will have to re-borrow the windows laptop at check the live data on Forscan. 

How easy is changing the starter motor? Doable with axle stands, or is a lift needed?

The starter is behind the engine and above the driveshaft.  So it is awkward to access, but if you're fairly agile it should be possible on axle stands.

I'm not particularly agile but can and have removed and refitted the starter motor a couple of times with the car on axle stands.

I recently had a similar issue - 2016 Focus 1.5L TDCi failing to start intermittently. I found the following YouTube video which correctly identified my problem, which was a rusty/corroded connection on the starter motor. I loosened and re-tightened the nut which seems to have fixed the problem.

 

19 hours ago, galgee said:

I recently had a similar issue - 2016 Focus 1.5L TDCi failing to start intermittently. I found the following YouTube video which correctly identified my problem, which was a rusty/corroded connection on the starter motor. I loosened and re-tightened the nut which seems to have fixed the problem.

 

Great, thanks! I’m away right now but will give that a go when I’m back. 

9 hours ago, ElCani said:

Great, thanks! I’m away right now but will give that a go when I’m back. 

No problem. I'd recommend removing as much of the rust/corrosion as possible using a wire brush or similar, if possible. I wasn't able to remove the nut on mine, and I have a feeling I'm going to have to look at it again sooner rather than later. 

Hi

I had a similar fault. Turned out battery sensor needed to be reset. 

Follow these instructions 

https://youtu.be/iV5Z4wO_yYQ?si=diR5lI6iTWwp15a-

On 7/23/2024 at 7:02 PM, galgee said:

I recently had a similar issue - 2016 Focus 1.5L TDCi failing to start intermittently. I found the following YouTube video which correctly identified my problem, which was a rusty/corroded connection on the starter motor. I loosened and re-tightened the nut which seems to have fixed the problem.

So... bought some axle stands and tried this with high hopes, but no joy 😒. Removed the nut and sanded it as well as wire-brushing the thread. I did an oil and filter change at the same time, though so most of the effort wasn't wasted. 

On 7/25/2024 at 3:06 AM, fogg85 said:

Hi

I had a similar fault. Turned out battery sensor needed to be reset. 

Follow these instructions 

https://youtu.be/iV5Z4wO_yYQ?si=diR5lI6iTWwp15a-

This was one of the first things I tried, but it made no difference. 

Just to update a bit on this… after I cleaned up the starter motor connection the problem was still there but was maybe a bit better. However, since then it has steadily improved to the point where it almost never happens, even during the very cold winter spell we had this year. As an added bonus, the stop-start feature has turned itself permanently off. Remembering to do this every time we drove the car was a big issue when the starting problem was bad.

So, no real clarity on what the cause of the problem is/was, but definite evidence for the theory that all problems eventually resolve themselves!