2008 bmw 535i cranks but wont start

I cannot start the car at all. I think that the battery is not the cause as all electrical components in the car are working properly. Both the outside and inside lights work. I tried to jump the car but it's unresponsive. The issue occurred out of the blue and I've never had any problems before. Do you have any idea what could be causing this?

Hey there, thanks for writing in about your 2008 BMW 535xi. A no crank, no start condition indicates a problem with the starting system. This could be the starter itself or the starting circuit. In your vehicle, power to the starter is directly controlled by the car access system module. This module decides when to activate the starter based on inputs from the transmission module (clutch module of you have a manual), start button and different parts of the anti-theft system. If power is not getting to the starter, it’s likely because the module is not receiving a proper signal from one of these items. If you’d like to have this checked, I recommend you have a professional, such as one from YourMechanic, inspect the starting problem firsthand and perform the correct repairs.

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      10-21-2015, 10:09 PM   #1

Enlisted Member

2008 bmw 535i cranks but wont start


Drives: e90

Join Date: Mar 2011

Location: florida

HELP(no communication with DME) car cranks but wont start


car was purchased as a not able to start vehicle
But it cranked. im the idiot and thought it was going to be something easy......
so here's the story ive looked high and low, everywhere online and spent enough $$ on this thing.
its an 08 535i but has the same DME (MSD81) the car cranks but doesnt start. i get the car scanned and it cannot communicate with DME,but can comm with all other computers just not the DME. i Send the DME out to get it checked, to verify the unit is bad and if it can be repaired. end result, unit is no good cannot be repaired. so i send the car to the stealership, purchase a brand new DME unit. they attempt to put in the DME and program it to the car and they cannot communicate with it as well.
now before all this happened. i checked all fuses and relays everything is good to make sure it wasn't anything stupid.
next after speaking with a BMW tech they said "if you can get the DME programmed outside of the car it should start" so i send off the new DME with the old along with EWS and key to get it matched with the car.
I get everything back and im just ready for this car to start. its been 3 months at this point. put a new battery in just to make sure everything has sufficient power and still no start and no comm with DME
if someone can point me to the slightest direction ill buy you beer or give alot of appreciation!

the lights that come up on the Idrive system and dash
CEL, ABS, low brake fluid, fuel pump inop, transmission Malfunction, TPM sensor resetting,

      10-22-2015, 02:04 AM   #2

First Lieutenant

2008 bmw 535i cranks but wont start
2008 bmw 535i cranks but wont start


Drives: BMW F30 320d

Join Date: Aug 2013

Location: Lisbon

On diesel cars, engine ecu (DDE on diesel, DME on petrol engines) is supplied by a relay next to the ecu. In this case is a green lime relay that stands on the box where ecu is. When this relay have problems, we get several errors on dashboard (abs,dtc, transmission, airbag and so on), engine cranks but won't work and we got no communication with the ecu. Try to see if on DME is like on DME.

      10-22-2015, 04:34 AM   #3

Colonel

2008 bmw 535i cranks but wont start


Drives: 2008 E90

Join Date: Feb 2012

Location: London

Indeed. Check relay and all wiring. DME unit sounds fine...

      10-23-2015, 03:44 AM   #4

Second Lieutenant

2008 bmw 535i cranks but wont start

2008 bmw 535i cranks but wont start

2008 bmw 535i cranks but wont start


Drives: 2009 335i , Alpine white

Join Date: Aug 2014

Location: Bmw Land , sims (nc)

I'm going to have to say bad wiring harness , wire burnt in wiring harness , etc . That's the only thing left that would cause the dme and car not to communicate properly

Ps if it's not a fuse

__________________

FBO , MHD , tuned

      10-23-2015, 02:16 PM   #5

Lieutenant

2008 bmw 535i cranks but wont start
2008 bmw 535i cranks but wont start
2008 bmw 535i cranks but wont start

2008 bmw 535i cranks but wont start

2008 bmw 535i cranks but wont start


Drives: F30 340i M Performance

Join Date: Nov 2008

Location: France

Check KGM junction box as can bus is routed to DME via this box ....

      10-23-2015, 03:57 PM   #6

Captain

2008 bmw 535i cranks but wont start
2008 bmw 535i cranks but wont start
2008 bmw 535i cranks but wont start
2008 bmw 535i cranks but wont start


Drives: Racecar

Join Date: Jul 2015

Location: Philly

Check to see the DME is even getting power.

If not, check the non-serviceable fuses on top of the battery. One of those supply the DME with power.

You have to buy the fuse panel to replace the fuses.

      11-02-2015, 11:49 PM   #7

Enlisted Member

2008 bmw 535i cranks but wont start


Drives: e90

Join Date: Mar 2011

Location: florida

after looking at wiring diagrams and fuses and relays im about to strangle someone. but i think we may have an answer. i read some elses post about the DME not communicating to other units because of the PT can bus. I get power to the DME, the wakeup line from CAS has voltage, only things left to check is to see why DME relay doesnt get flipped and if the PT can bus is messed up. i think we almost have an answer here. if i take too much more time on it i will just buy all modules from parts car and get the wiring harness.

      11-03-2015, 09:25 AM   #8

Major

2008 bmw 535i cranks but wont start

2008 bmw 535i cranks but wont start

2008 bmw 535i cranks but wont start


Drives: 335d M-Sport

Join Date: Jul 2014

Location: Greater Detroit

You're on the right track. Try to borrow a good oscilloscope from someone and take a look at the CAN communication. Check for error frames and specific messages generated by the DME.
If there are no messages generated by the DME it's most likely some power issue to the DME. Check all supply voltages at the DME connectors.
Sometimes the connectors get corroded, take a few out and see if they appear intact. Sometimes critters get into the engine bay and nip away on cables - look for those spots.

      11-11-2015, 07:43 PM   #9

Enlisted Member

2008 bmw 535i cranks but wont start


Drives: e90

Join Date: Mar 2011

Location: florida

more and more we look at it seems like the DME is to be the culprit. could BMW have sold me a bad unit? if this is the case i'm about to rip them a new one. PT can bus looks to be sending signal. going check all grounds and power again to the DME but i feel like i'm going around in circles at this point. CAS sends signAl KGM sends signal, wake up line gets power. if i put in another DME would doing that brick any of the modules in the car?

      11-12-2015, 08:16 PM   #10

2008 bmw 535i cranks but wont start

2008 bmw 535i cranks but wont start


Drives: 335i

Join Date: Jun 2007

Location: US

I once had to sync the DME to EWS to make it work...Use Inpa

      11-12-2015, 08:51 PM   #11

Lieutenant

2008 bmw 535i cranks but wont start
2008 bmw 535i cranks but wont start
2008 bmw 535i cranks but wont start

2008 bmw 535i cranks but wont start

2008 bmw 535i cranks but wont start


Drives: 2008 BMW 335xi 6spd

Join Date: Oct 2015

Location: Orange/Rockland

How did you check pt can? You can have voltage but no signal.

It fluctuates to fast to pick up on a DVOM, need an oscilloscope.

Also can you post the wiring diagram.

You check grounds not just power, resistances and for shorts ?

      11-12-2015, 08:52 PM   #12

Lieutenant

2008 bmw 535i cranks but wont start
2008 bmw 535i cranks but wont start
2008 bmw 535i cranks but wont start

2008 bmw 535i cranks but wont start

2008 bmw 535i cranks but wont start


Drives: 2008 BMW 335xi 6spd

Join Date: Oct 2015

Location: Orange/Rockland

Quote:

Originally Posted by cn555ic

2008 bmw 535i cranks but wont start

I once had to sync the DME to EWS to make it work...Use Inpa

This is when the DME and ews aren't aligned properly. Different scenario.

      11-12-2015, 08:54 PM   #13

Lieutenant

2008 bmw 535i cranks but wont start
2008 bmw 535i cranks but wont start
2008 bmw 535i cranks but wont start

2008 bmw 535i cranks but wont start

2008 bmw 535i cranks but wont start


Drives: 2008 BMW 335xi 6spd

Join Date: Oct 2015

Location: Orange/Rockland

Send me the last 7 or post a wiring diagram so I can pull it

      11-13-2015, 06:31 AM   #14

Enlisted Member

2008 bmw 535i cranks but wont start


Drives: e90

Join Date: Mar 2011

Location: florida

I dont have that oscilloscope. but what i did was check for change in Voltage, depending on if i had the car in ACC or off, it did have a different signal. what I was initially checking for was a break in the wiring somewhere. For the OBD port I have 3.33 resistance going to OBD from DME. I checked all the grounds with the DME had 0 resistance. I will post diagram when I get home today. Still seems to me that its the DME, the DME relay isnt clicking on unless i ground the line that goes to sensor on throttle body. ill get diagrams and we can take a look

      11-13-2015, 06:33 AM   #15

Enlisted Member

2008 bmw 535i cranks but wont start


Drives: e90

Join Date: Mar 2011

Location: florida

also CAS and EWS were synced outside of the car. there was never the OBD connection to sync them in the car

      11-13-2015, 01:03 PM   #16

Captain

2008 bmw 535i cranks but wont start
2008 bmw 535i cranks but wont start
2008 bmw 535i cranks but wont start
2008 bmw 535i cranks but wont start


Drives: Racecar

Join Date: Jul 2015

Location: Philly

Quote:

Originally Posted by cn555ic

2008 bmw 535i cranks but wont start

I once had to sync the DME to EWS to make it work...Use Inpa

When DME and EWS become out of alignment, the ignition cannot be switched.

Otherwise, in a manual transmission car, the car can be push started. If ignition is switched, all the DME needs to inject fuel and ignite the mixture is crankshaft movement.

That being said, I would check the crankshaft position sensor.

Bad, false, and no reading from this sensor means the DME will not know when/if to inject fuel or fire the spark plugs.

      11-13-2015, 01:08 PM   #17

Captain

2008 bmw 535i cranks but wont start
2008 bmw 535i cranks but wont start
2008 bmw 535i cranks but wont start
2008 bmw 535i cranks but wont start


Drives: Racecar

Join Date: Jul 2015

Location: Philly

Forgot you had issues with CAN coms......being a N54 car, Is there a JB4 on this car?

JB4 will not allow CAN access in maps other than 0 and 4.

      11-15-2015, 08:51 AM   #18

Enlisted Member

2008 bmw 535i cranks but wont start


Drives: e90

Join Date: Mar 2011

Location: florida

there is no JB4 in this car.
i have a pdf of basic diagram for engine start
I was definitely considering if the CPS was bad but if that were the case i would still be able to read the DME and would not get error codes FOR
fuel pump, transmission, ABS,

      10-21-2016, 03:53 PM   #19

Registered


Drives: 2007 BMW N54 E92

Join Date: Jan 2016

Location: Salt Lake City, UT

Quote:

Originally Posted by Matrad

2008 bmw 535i cranks but wont start

there is no JB4 in this car.
i have a pdf of basic diagram for engine start
I was definitely considering if the CPS was bad but if that were the case i would still be able to read the DME and would not get error codes FOR
fuel pump, transmission, ABS,

Was there a final resolution to this? I'm running into a similar problem, and am wondering how this was fixed.

      10-21-2016, 09:02 PM   #20

Major

2008 bmw 535i cranks but wont start

2008 bmw 535i cranks but wont start

2008 bmw 535i cranks but wont start


Drives: 2009 335i M Sport

Join Date: Mar 2011

Location: Knoxville, TN

Quote:

Originally Posted by deftones80

2008 bmw 535i cranks but wont start

Was there a final resolution to this? I'm running into a similar problem, and am wondering how this was fixed.

What caused your issues? Would help in troubleshooting.

      11-11-2016, 04:02 PM   #21

Registered


Drives: 2007 BMW N54 E92

Join Date: Jan 2016

Location: Salt Lake City, UT

Quote:

Originally Posted by Joe@TopGearSolutions

2008 bmw 535i cranks but wont start

What caused your issues? Would help in troubleshooting.

My motor was swapped out, new motor cranks, but will not turn on. Plugged in ISTA software and found that the DME is not getting power. Ran through all of the fuses and found no issues. I purchased a used DME and had it coded to my VIN and synched to the CAS and keyfob, plugged in the new DME, but still not getting any power. Run through all of the connections and all appears to be in good order, but we're still not getting any power or signal to the DME. Any thoughts?

      11-12-2016, 10:59 AM   #22

Lieutenant

2008 bmw 535i cranks but wont start
2008 bmw 535i cranks but wont start
2008 bmw 535i cranks but wont start

2008 bmw 535i cranks but wont start

2008 bmw 535i cranks but wont start


Drives: F30 340i M Performance

Join Date: Nov 2008

Location: France

faulty relay in junction box ?

Why is my car cranking but not starting?

If the car cranks when you turn the key, but the engine won't start, it could be because fuel isn't getting to the engine. One potential reason for this could be dirty fuel injectors. Over time, the fuel injector nozzles can become clogged with rust, corrosion or debris.

Can a fuse cause a BMW not to start?

Check Fuses / Relays Your BMW may not start due to a blown a fuse or a bad relay. Checking the fuses on a BMW is very easy. You can remove the fuse and visually inspect fuses. You can also check with a digital multimeter.

Why is my BMW clicking but not starting?

It might be a battery or alternator problem. Perhaps your battery's dead, or your alternator, which charges the battery, isn't working correctly. If the source of the clicking is electrical, the starter (a small motor energized by the battery that gets the engine running) doesn't have enough juice to stay powered.