No crank no start

ALICIA BRENT

MEMBER
2002 BMW 745
3.8L
V8
AUTOMATIC
180,000 MILES

The car was starting right up every time then replaced the power steering pump. After that had to bleed power steering car goes into limp mode and won't start, but with a jump it would and alternator is good. So got a new battery and installed it car starts still in limp mode keeps going in and out of limp mode. Then next morning battery was drained to battery back to have it charged. Checked all fuses then put battery back in and started up then next morning battery dead again. So got a jump and this time no crank no start. So I tried to test battery and it had 12v before it was showing something was pulling 3.92 from my battery this time it's not so I push on brake pedal while key in and push start put in second position and I keep pumping on the brake finally car starts. Then I can't get it to stay running it just cuts off every light on the dash is lit up!

5 Replies

KASEKENNY

MECHANIC
18,907 POSTS

Hi Alicia,

This is an odd one. I don't see any correlation to the issue you have now to just replacing the power steering pump. Did you take any connectors apart in order to get to the power steering pump? If so, recheck each of those to ensure they are seated properly.

If that checks out and you still have this issue, the only thing I can suggest is to obtain all the codes in the computer. I am sure you will find a lot of loss of communication codes if all your lights on the dash are on. If this is the case, then that would support the suggestion that you left a connector apart or not fully seated.

If you don't find anything, get the codes and send them back and I can be of more assistance because based on this information, these have nothing to do with each other. Thanks

SPONSORED LINKS

Was this

answer

helpful?

Yes

No

+1

Sunday, April 28th, 2019 AT 1:07 PM

ALICIA BRENT

MEMBER
5 POSTS

I know right it has me really stumped! When I bought the car it drove fine except the power steering then it went into limp mode I replayed the power steering pump bled it but still it was in limp mode put oil in the car because it was low then it went out of limp mode after that the battery was something was draining the battery but I thought the battery was bad so I got a new one then installed it and same thing still in limp mode. So I was watching you tube videos and spoke to a BMW mechanic he said the battery needed to be registered and programmed to the car but my car was still starting up tried to hook up obd2 but it just says it can't communicate with the computer then I tried my brothers mobile magic mechanic Bluetooth device and it showed a code for the throttle body sensor chamber A I don't know exactly the code I have it at the house I'll let you know but I figured I'd try to clean the throttle body because it was really dirty and since the car goes in and out of limp mode thought it just might be really dirty! Now my car is not recognizing the key so my car will not crank or turn over it's like the computer is going crazy from one thing to another oh and all the sudden battery I'd not getting drained. I just don't get it!

Was this

answer

helpful?

Yes

No

Sunday, April 28th, 2019 AT 1:57 PM

KASEKENNY

MECHANIC
18,907 POSTS

Did you just buy this car and how long have you owned it since these issues started?

A dirty throttle body is not going to cause the vehicle to go into limp in or act the way you are describing. If your mechanic said that the computer cannot communicate that is where you need to start. It sounds like you have a network communication issue. These diagnostic computers communicate on the same network that the vehicle's modules communicate on. So if the scan tool does not work, then most likely the vehicle's modules cannot communicate either, which will explain all your issues including the limp in mode and not start, and not recognizing the key. The code scanner does not communicate on these networks which is why it was able to get the codes however, it did not pull all the codes. It only pulled the ones, most likely from the PCM.

Let me know how long you have owned this and if they started right after you bought the car and we can go from there. Thanks

Was this

answer

helpful?

Yes

No

+1

Sunday, April 28th, 2019 AT 2:06 PM

ALICIA BRENT

MEMBER
5 POSTS

Yes I just bought the car about a month ago, and everything started right after I bought it! So what's the first step we need to take? This car is driving me absolutely insane!

Was this

answer

helpful?

Yes

No

Sunday, April 28th, 2019 AT 2:27 PM

KASEKENNY

MECHANIC
18,907 POSTS

Is returning to where you bought it an option? I am not suggesting taking it back (return it) but if you bought it from a used car lot or business of some sort they usually carry a warranty on it for a few weeks or months in the event something happens.

If not, or you bought it from an individual, I would suggest calling around and finding a mechanic that specializes in either electrical communication network diagnoses (BUS networks) or works on a lot of BMW's. You do not want to take an issue like this to just any shop. If it is what I suspect, then you don't want to pay someone to guess at it. There is a specific way to diagnose these types of issues and if they are not familiar with these types of networks or these cars, I would not take it to them. Basically, you want to interview them and see if they sounds like they know what they are talking about. Too often, people just pay the diagnosis and it seems endless and then are left with a large bill and no resolution because the tech working on it didn't actually know what they were doing.

It may turn out to be something very simple like a single module or more complicated like a wiring harness. Either way, we need to start with why the BMW tech could not communicate with the integrated module. Once they start to peel that back, they may find the root cause.

Sorry I don't have a silver bullet for you but this one seems much more complicated.