My car wont crank over when I go to turn the key, but all electrical stuff works fine.

Tiny
94BMW740I
  • MEMBER
  • 1994 BMW 740
  • 240,000 MILES
When I got in my car today to go to work, I went to turn the key and it would not crank, it spun over just fine and all the lights and radio, etc came on on the dash like normal. There were no new warning lights, and no warning for this at all. I checked the battery and its good, and made sure it was connected good, clean, and tight. I've heard there is a lot of corrosion that goes on with bmw wirings, so I thought maybe that could be it somewhere? I'm lost, and desperately need this car back up and running so I can get back and forth to work! I love this car and this is the first problem I've had with it in 7 months! Please help if you can! Oh, and when you turn the key over the last position to crank it, there is a very faint humming under the hood, and it stops when you let go of the key. Not sure if that's any help.

1994 740I v8
Thursday, August 2nd, 2012 AT 7:03 AM

6 Replies

Tiny
ASEMASTER6371
  • MECHANIC
  • 52,797 POSTS
Basics first, compression test, fuel pressure and spark test. One of these will be missing. Then we can proceed.

Roy
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Thursday, August 2nd, 2012 AT 10:11 AM
Tiny
MIKEDEROUIN88
  • MEMBER
  • 137 POSTS
If I'm understanding you correctly it doesn't turn over at all? Check all ignition fuses and relays, if all check good check for power to the smaller wire on the solenoid with key in on position. If there is power have the starter checked if not check ignition switch.
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Thursday, August 2nd, 2012 AT 10:49 AM
Tiny
ASEMASTER6371
  • MECHANIC
  • 52,797 POSTS
Sounds like the starter is turning but not starting

Roy
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Thursday, August 2nd, 2012 AT 12:49 PM
Tiny
94BMW740I
  • MEMBER
  • 3 POSTS
I believe that's what its doing Roy, could it be something simple like a break in a wire, or corrosion?
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Thursday, August 2nd, 2012 AT 2:51 PM
Tiny
94BMW740I
  • MEMBER
  • 3 POSTS
And that's correct, it doesn't turn over at all. When you turn the key to position 1 everything lights up like normal, then when you go to crank it over it doesn't do anything. But if you hold the key in the crank position you can slightly hear a humming from under the hood, when you let the key turn back it stops. Is this the starter trying? Or?
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Thursday, August 2nd, 2012 AT 2:53 PM
Tiny
ASEMASTER6371
  • MECHANIC
  • 52,797 POSTS
Possibly, clean the battery cables and have the battery checked for load. If it is ok, you may have a failed starter motor.

Roy
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Thursday, August 2nd, 2012 AT 4:47 PM

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