Is there a starter relay? (E86) update: immobiliser/DME (now solved)

[Liam22]

I was wiring up a switch to control power to the steering angle sensor and accidentally shorted the wire. It is permanently live!

Now the car won't start. All lights on dash, fuel pump primes, usual clicks in the engine bay. But no activity when turning the key to start.

No low battery solenoid clicks, nothing.

Replaced the starter motor but no change.

Thinking I may have fried the starter relay (or worse) but cannot find it. Any pointers?

 

[Liam22]

Forgot to add, there is 12V at the steering column switch when I turn the key to start.

 

[Liam22]

Spent some more time trying to diagnose this problem, before I throw my hands up and call an auto electrician...

Confirmed that there is no voltage reaching the trigger wire on the starter solenoid.

Tried to trace the blue/black wire from the ignition switch but lost track of it. I am certain that it doesn't go to the main fusebox but I swapped all the attached relays from side to side just in case.

Instead tried to trace the (white) starter trigger wire backwards and found a junction box hiding below the throttle body. Couldn't find an easy way to get inside. I did find a white wire of the same size inside the DME housing but no voltage there either.

Then I remembered that I have a code reader. Doh!



When I try to interrogate the EWS there is nothing there.



Does anyone know if the EWS/immobiliser is a separate unit, or integrated with the DME?

 

[Liam22]

Found it.

Followed this excellent guide
https://www.rpmmotorsport.net/pages/ews-3-test-before-replacement

Wasn't getting voltage to EWS pin 11. Checked the corresponding fuse (no.12) and it wasn't bloody there!!!

I must have forgotten to replace it when I checked all the other fuses. Swapped it for the horn 5A fuse (no.14) and all good.

Turns out the brake lights permanently illuminate without fuse 14... jeez I hate electrics!

 

[lucasxdiniz]

Nice diagnosing! Always nice when people leave updates for posterity

 

[Liam22]

I have no problem publicly shaming myself for being stupid

On the plus side, changing the starter motor was much easier than I expected, given it's location. And I only spent £30 on a second hand item from a 2012 E90. So now I have a "fresher" starter and a good spare