Troubleshooting a no-crank issue

[E46m3zcp]

Just bumping this because there were unrelated replies, and it could make my last reply with the latest development less visible.

As of now, I have ruled out the battery and the starter, and I'm investigating an SMG-related issue that could make the clutch position not satisfactory for the EWS to unlock the starter (more specifically, it looks like it is periodically unlocking/locking it back too quickly for the engine to have time to start). Any hints from people having seen these symptoms much appreciated!

EDIT: I tried bleeding the SMG system with INPA, no progress. I am suspicious of the clutch sensor and slave cylinder, but unsure how to test that (I'd like to avoid removing the aluminum plate, as the bolts are TTY and technically need replacement).

Symptoms recap

• No crank.
• INPA “starter not powered because of …” toggles between Clutch actuation and None.
• Relay-like clicking sound.
• Bypassing EWS pin 1 & 2 makes the starter crank normally.
• Battery & starter are known good.
• Bled SMG (because of the clutch actuation symptom), but no-crank remains.
• No SMG fault codes currently stored.

SEE: https://www.youtube.com/shorts/E5rugnuuR1U

[E46m3zcp]

ok the end of the saga is a bit disappointing. It was my ignition switch that was failing intermittently. This mislead me when I was putting the fuse in the EWS pin 1/2 and the car was cranking. I noticed that once every 5 attempt on average it wouldn't crank, then the frequency started dropping until it wasn't starting anymore.

I was also mislead by apparent SMG symptoms based on observation in the EWS INPA module that the clutch signal was preventing EWS to activate the starter (see my video above). To rule out the clutch problem, I followed steps to code the EWS to ignore the clutch position:

https://www.e46fanatics.com/threads/diy-how-to-code-ews-to-disable-clutch-park-neutral-switch.1313143/

After coding this, the clicking stopped (it went to a no-crank without any clicking, typical from a bad EWS or Ignition switch). This means that the clicking was the SMG solenoid for the clutch, as the car was getting some signal from the EWS to start, but since the ignition signal didn't reach the starter the system was giving up and letting go the clutch, then cycling again (I don't really understand deeply the reasons behind that, it could be how it's programmed to operate when it's not getting a starter signal despite the OK from the EWS).

Once I realized that coding that out didn't solve the issue, I concluded that the problem wasn't related to the clutch position sensor (builtin into the slave cylinder on the SMG).

Then 2 possibilities were remaining: EWS or Ignition switch. See this video: https://www.youtube.com/watch?v=LUYgSFgc7-c
At this moment the ignition switch completely failed (it was until then intermittent, so very confusing).

Since I have 2 M3, the solution was simple, swap out the ignition switch and see if it solve the problem, and it did. I coded back the EWS to factory specs, and everything works now.

[sapote]

After your hack of bypassing the EWS, I get cranking and so my conclusion is that the problem was corrosion on the terminals.
.

What terminals? Key switch terminals? Bypassing EWS with fuse can't help with a bad switch terminal.
I think the problem is the EWS internal relay. Could also be its input signals (N, clutch, SMG pressure sensor, etc) but in this case the starter should not even clicking.

[sapote]

Well well,

After reenabling the EWS, the syptoms are back. But at least now I know it isn't the starter! (I could have just shorted EWS pin 1 and 2 and known this without removing the airbox, but now I know!)

I suspect some SMG components (like the slave cylinder) to be the cause. It looks like the clutch disengages for a brief period, but bounces back before the starter has time to spin. It sounds like the slave cylinder pushes the clutch, then lets it go immediately.
Take a look:

EWS: https://www.youtube.com/shorts/E5rugnuuR1U
SMG Digital 1: https://www.youtube.com/shorts/-_O0caQYSxM

Any reason not to leave the fuse in until I get some free time to tackle this? I guess that would mean I'd have to be more careful not mistakenly turning the key while the car is in gear (like good ol' 90's cars)

Bypassing ews can kill the key switch earlier as all 10A starter solenoid current flows thru the switch contacts. This is why the EWS has an output relay.

[sapote]

ok the end of the saga is a bit disappointing. It was my ignition switch that was failing intermittently. This mislead me when I was putting the fuse in the EWS pin 1/2 and the car was cranking. I noticed that once every 5 attempt on average it wouldn't crank, then the frequency started dropping until it wasn't starting anymore.

I was also mislead by apparent SMG symptoms based on observation in the EWS INPA module that the clutch signal was preventing EWS to activate the starter (see my video above). To rule out the clutch problem, I followed steps to code the EWS to ignore the clutch position:

https://www.e46fanatics.com/threads/diy-how-to-code-ews-to-disable-clutch-park-neutral-switch.1313143/

After coding this, the clicking stopped (it went to a no-crank without any clicking, typical from a bad EWS or Ignition switch). This means that the clicking was the SMG solenoid for the clutch, as the car was getting some signal from the EWS to start, but since the ignition signal didn't reach the starter the system was giving up and letting go the clutch, then cycling again (I don't really understand deeply the reasons behind that, it could be how it's programmed to operate when it's not getting a starter signal despite the OK from the EWS).

Once I realized that coding that out didn't solve the issue, I concluded that the problem wasn't related to the clutch position sensor (builtin into the slave cylinder on the SMG).

Then 2 possibilities were remaining: EWS or Ignition switch. See this video: https://www.youtube.com/watch?v=LUYgSFgc7-c
At this moment the ignition switch completely failed (it was until then intermittent, so very confusing).

Since I have 2 M3, the solution was simple, swap out the ignition switch and see if it solve the problem, and it did. I coded back the EWS to factory specs, and everything works now.

SMG clutch sensor has nothing to do with EWS enable/disable.
If the key switch is the root cause, then why connecting switch signal via the bypass fuse caused the starter to run?