Hey guys recently go an e60 08 528i wife was driving for a couple months before she started running into an issue. When trying to start the car the car stops cranking suddenly and doesn't run.
After multiple pushes of the button the car started fine. Of course when i got to the car it started just fine. I decided to drive the car for a while to see if i could get it to act up again. Low and behold left me stranded now to have towed to my shop. Code present in pcm is 2acb ive swapped the dme realy (blue relay in junction block by fire wall) had power at all the right pins and ground from the dme. Ive checked my resistance from pcm connector pin 13 to dme relay and have a proper .5 ohms. I have checked all ground wires from dme to ground next to junction block all have about .4- .5 ohms. while trying to start the relay does lose its ground but comes right back after the car stops attempting to start. I was thinking possible a crank sensor however i have rpm and i dont see how the car would attempt to start but not keep cranking. i found the ibs connector disconnected and reconnected it. Also checked ground strap it is new and installed properly. anyone have any idea? cars really being a pain in my ass. Thanks in advance

 

There is a braided ground strap under the car on the right side about inline with the front wheel. It connects to the chassis just aft of the wheel well and to the car on the AWD drive shaft mount if an AWD car or to the engine of not AWD. That cable gets brittle and can end up as a weak or broken ground and cause all sorts of issues. You can see the cable if you look down in the right spot between the fender and the engine on the right side down under the car. It is probably green-ish tinted at this point.

 

Are you referring to the one connected to the engine mount bolt? Just trying to get clarification for the OP

 

Yes, I suppose it is...my car is AWD and that is connected to the drive shaft mount, but they are both in the same vicinity.

 

Yes the ground is new and installed properly. Previous owner changed it sometime recently.

 

Heres as long as a video i can post on here to show what its doing. The starter is newer (6 months old)