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Discussion Starter #1
Hi, my name is Jerry and I I got this 09 Mini Cooper s. It had the classic timing chain failure. All exhaust valves bent. Repaired everything and the car runs great. Now the starter intermittently cranks long enough to start the car. Most of the time it starter just sounds like it tries to turn for a second or two, then just stops even if I hold the button down. I can keep trying and after 5-10 tries, it finally cranks long enough to start the car. I put a new battery in. Same problem. I can hear all kinds of clicks from relay or relays. Any ideas on how to diagnose the starter system? Or what it could be? Thanks in advance.
 

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sounds like to me the motor part of starter has got a dead segment on motor side maybe or the solenoid part is failing either-way its starter motor,, if you have start stop option on car and use t a lot then they tend to last around 70,000 miles of mixed driving less if only ever get used in town and traffic,,, normally if CAS unit fails they just dont start and get no 12v feed to starter small switch wire, also i would use a jump lead and go from neg on battery to a metal part of engine,, if car then starts first time every time you will know its a earth problem common for small earth cable on top engine mount to corrode or get damaged from maybe removing the engine mount when done timing chain and head issues
 

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Thanks Mike, I’ll give all that a look. Seems to me the signal wire voltage to the solenoid is being cut the way the starter is acting. I’m trying to understand the way this push button start works, how and when it cuts power to the starter once it starts? I am assuming through a module or relay. I can’t seem to find a “how to diagnose a starter system for this car.
 

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i would put a volt meter on the small wire to starter motor, this when the button is pressed should read a solid battery voltage ie fully charged battery 12.8v, then no volts after car starts, this wire goes to bcm body control module the bcm is controlled by the cas unit the cas unit lives under the top piece of dash and is a royal pain in arse to get at, the cas unit is all part of security system and immobiliser system the bcm and cas unit and keys and main ecu and rev counter and speedo are all coded to each other , below link explains the bmw CAS unit
 

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Thanks for that info. I think I check the wire for voltage while the button was pushed and I got only a second of voltage. I will double check it. I assume if the cas or BCM are at fault, any new parts have to be programmed by the dealer?
 

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Discussion Starter #7
I finally got time to work on this no crank problem. Now the key get locked in the dash, I just keep pushing it in and it finally pops out. It’s a manual trans. So it’s not like an automatic trans that has to be in park to get the key out. Now sometimes the dash lights up and sometimes doesn’t when I put the key in. Sometimes the starter turns for a second and will keep doing it everytime I push the button. Other times not even a click. Wish I could find a wireing diagram for the starter system. I took the dash apart to get the key slot out and disconnect the ribbon cable and reconnect it. I put the key in and dash lit up with chimes, then the key was stuck again so I unplugged it, dash lights and chimes continue and key still would not release. Plugged it back in and kept pressing it and finally popped out. I also noticed the brake lights were on several times for no reason. I opened the remote and made sure it had 3v. I charged the battery in the car to make sure it has full voltage. I can’t figure out what is cutting the voltage to the starter solenoid. Any ideas???
 
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