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

Matrad · 10-21-2015, 10:09 PM

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,

Dtype · 10-22-2015, 02:04 AM

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.

Sensible_ · 10-22-2015, 04:34 AM

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

JDuke335i · 10-23-2015, 03:44 AM

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

frenchi · 10-23-2015, 02:16 PM

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

matteblue3er · 10-23-2015, 03:57 PM

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.

Matrad · 11-02-2015, 11:49 PM

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.

Mik325tds · 11-03-2015, 09:25 AM

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.

Matrad · 11-11-2015, 07:43 PM

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?

cn555ic · 11-12-2015, 08:16 PM

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

Abax335 · 11-12-2015, 08:51 PM

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 ?

Abax335 · 11-12-2015, 08:52 PM

Quote:

Originally Posted by cn555ic

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.

Abax335 · 11-12-2015, 08:54 PM

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

Matrad · 11-13-2015, 06:31 AM

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

Matrad · 11-13-2015, 06:33 AM

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

matteblue3er · 11-13-2015, 01:03 PM

Quote:

Originally Posted by cn555ic

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.

matteblue3er · 11-13-2015, 01:08 PM

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.

Matrad · 11-15-2015, 08:51 AM

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,

deftones80 · 10-21-2016, 03:53 PM

Quote:

Originally Posted by Matrad

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.

Joe@TopGearSolutions · 10-21-2016, 09:02 PM

Quote:

Originally Posted by deftones80

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.

deftones80 · 11-11-2016, 04:02 PM

Quote:

Originally Posted by Joe@TopGearSolutions

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?

frenchi · 11-12-2016, 10:59 AM

faulty relay in junction box ?

10-21-2015, 10:09 PM	#1
Matrad Enlisted Member 11 Rep 34 Posts Drives: e90 Join Date: Mar 2011 Location: florida iTrader: (0)	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,
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10-22-2015, 02:04 AM	#2
Dtype First Lieutenant 36 Rep 398 Posts Drives: BMW F30 320d Join Date: Aug 2013 Location: Lisbon iTrader: (0)	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.
	Appreciate 0 Quote

10-22-2015, 04:34 AM	#3
Sensible_ Colonel 529 Rep 2,504 Posts Drives: 2008 E90 Join Date: Feb 2012 Location: London iTrader: (1)	Indeed. Check relay and all wiring. DME unit sounds fine...
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10-23-2015, 03:44 AM	#4
JDuke335i Second Lieutenant 57 Rep 272 Posts Drives: 2009 335i , Alpine white Join Date: Aug 2014 Location: Bmw Land , sims (nc) iTrader: (0)	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
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10-23-2015, 02:16 PM	#5
frenchi Lieutenant 89 Rep 452 Posts Drives: F30 340i M Performance Join Date: Nov 2008 Location: France iTrader: (11)	Check KGM junction box as can bus is routed to DME via this box ....
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10-23-2015, 03:57 PM	#6
matteblue3er Captain 238 Rep 947 Posts Drives: Racecar Join Date: Jul 2015 Location: Philly iTrader: (0)	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.
	Appreciate 0 Quote

11-02-2015, 11:49 PM	#7
Matrad Enlisted Member 11 Rep 34 Posts Drives: e90 Join Date: Mar 2011 Location: florida iTrader: (0)	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.
	Appreciate 0 Quote

11-03-2015, 09:25 AM	#8
Mik325tds Major 806 Rep 1,191 Posts Drives: 335d M-Sport Join Date: Jul 2014 Location: Greater Detroit iTrader: (0)	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.
	Appreciate 0 Quote

11-11-2015, 07:43 PM	#9
Matrad Enlisted Member 11 Rep 34 Posts Drives: e90 Join Date: Mar 2011 Location: florida iTrader: (0)	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?
	Appreciate 0 Quote

11-12-2015, 08:16 PM	#10
cn555ic 441 Rep 18,331 Posts Drives: 335i Join Date: Jun 2007 Location: US iTrader: (6)	I once had to sync the DME to EWS to make it work...Use Inpa
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11-12-2015, 08:51 PM	#11
Abax335 Lieutenant 79 Rep 540 Posts Drives: 2008 BMW 335xi 6spd Join Date: Oct 2015 Location: Orange/Rockland iTrader: (1)	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 ?
	Appreciate 0 Quote

11-12-2015, 08:54 PM	#13
Abax335 Lieutenant 79 Rep 540 Posts Drives: 2008 BMW 335xi 6spd Join Date: Oct 2015 Location: Orange/Rockland iTrader: (1)	Send me the last 7 or post a wiring diagram so I can pull it
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11-13-2015, 06:31 AM	#14
Matrad Enlisted Member 11 Rep 34 Posts Drives: e90 Join Date: Mar 2011 Location: florida iTrader: (0)	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
	Appreciate 0 Quote

11-13-2015, 06:33 AM	#15
Matrad Enlisted Member 11 Rep 34 Posts Drives: e90 Join Date: Mar 2011 Location: florida iTrader: (0)	also CAS and EWS were synced outside of the car. there was never the OBD connection to sync them in the car
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11-13-2015, 01:08 PM	#17
matteblue3er Captain 238 Rep 947 Posts Drives: Racecar Join Date: Jul 2015 Location: Philly iTrader: (0)	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.
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11-12-2016, 10:59 AM	#22
frenchi Lieutenant 89 Rep 452 Posts Drives: F30 340i M Performance Join Date: Nov 2008 Location: France iTrader: (11)	faulty relay in junction box ?
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