Chances my ECU is knackered?

funk-you

Hey guys,

Hoping for a bit of help or advice. So my beloved car has decided she doesn't want to perform her most basic function anymore (drive) and she won't even talk to me.

It's a 2007 BMW 320i Coupe. I drove home from work on Thursday evening as normal with no issues at all. On Friday morning (after the really cold storm) I went out and went to start it up but the engine tries to turn over but doesn't start, it's flashing dash lights for ABS/Tyres/DTS/airbags etc. now. Tried jumpstart but that's not it. Windows/lights/central locking/radio etc. all work fine.

I hooked up to the OBDII and I'm connecting to the dongle but the ECU isn't talking from what I can see. (Tested the dongle on the OH's car just in case and it works perfectly.

I called out roadside assist and they tried 3 separate devices to the ODBII and the same thing. He checked all the fuses etc and said they are all perfect. I've gone through all the sensors and down to the ECU itself and cleaned and reseated all the terminals/connections. Put it all back together and still the same thing, tries to turn over but no start and lots of the errors above.

The reason I'm thinking ECU is the sheer amount of sensors saying they're failed and the ECU won't communicate with anything we've hooked up to it.

What are the chances I'm looking at a knackered ECU and does anyone know a good BMW indy that's a dab hand at diagnosing/repairing something similar? If it's just a case of sensor/part replacement anyone thinks it could be, I can swap them out myself but know next to nothing about ECU's so don't want to mess with it if that is the likely culprit because I've no software for it.

Does it sound like I'm chasing the right line of thinking here?

gctest50

battery failed maybe ? if the voltage goes too low while its cranking over the ECU won't be able to function properly

seen it lately - cranking over ok-ish , voltage too low while cranking though

funk-you

Aye, we stuck a battery booster on her while the roadside assist guy was there hoping it was just the battery but no joy. Would it make any difference that I used the terminal in the engine bay rather than the battery itself in the boot?

-Funk

gctest50

Thats the terminal to use for jumping ok
- don't go jumping onto the battery itself
- some have "intelligent charging" - the alternator/charging system has a little controller and it learns the state of the battery
- its not going to like being prodded with a jump cable



the battery could still be bad though and pulling the system voltage down though - can give gearbox errors on the automatic ones


if it has the "advanced dashboard" thingy ( dunno what bmw call it ) , it shows the system voltage under a hidden menu

( its a bit like an ancient digital watch :

find the VIN number , add up the last six digits and write it down

eg: 66731 = 6 + 6 + 7 + 3 +1 = 23

hold down the button until the hidden menu pops up
scroll down to unlock
put in the number you wrote down
scroll back up to system voltage )


If it doesn't have that stick a meter on the ECU and see what voltage its getting

VERY easy to cause expensive damage to on board electronics doing this

eg :

gearbox module 2500

http://www.ecstuning.com/BMW-E65-750i-N62_4.8L/Drivetrain/Automatic_Transmission/ES2748339/

funk-you

Great, thanks man. I'll check what voltage it's showing as soon as I get in from work.

-Funk

funk-you

So, I checked the voltage when I got into the car and it was showing 11.9V. Tried to start it again and dropped to 11.2V. Put a booster on and got it up to 12.2V, tried again, no joy. Disconnected the IBS just in case it was giving problems too but the same symptoms

Having a bad day.

-Funk

Pov06

Is it an E46 or E92?

funk-you

Sorry, yep an E92.

-Funk

funk-you

Okay, to update this one in case anyone has the same problem down the line. The garage swapped out many fuses with no joy. Then moved onto the power distribution box, again with no joy. Then replaced the ECU and she fired up no problem. 1 ECU and 1200 quid later my car is working perfectly again.

-Funk

ofcork

Ouch sister has one gone in her 07 320d m sport so has no radio or sat nav working.

Special Circumstances

ofcork wrote: »

Ouch sister has one gone in her 07 320d m sport so has no radio or sat nav working.

??? Be the least of your worries if the ecu went?

Graham

Sounds like this might be too late to be of any use to you OP but this company have been recommended to us. We're about to send off an ECU to them:

http://www.ecutesting.com/catalogue/bmw_eculist.html?category=4046&model=465

Might be useful for anyone searching in the future.

DublinDilbert

funk-you wrote: »

Okay, to update this one in case anyone has the same problem down the line. The garage swapped out many fuses with no joy. Then moved onto the power distribution box, again with no joy. Then replaced the ECU and she fired up no problem. 1 ECU and 1200 quid later my car is working perfectly again.

-Funk

Is there any water marks or corrosion on the old ecu?

Drain hole in the bottom of the ecu enclosure gets blocked and fills with water. Cpu reset generator is at bottom of pcb and doesn't like getting wet. The e90 ecus i've seen are even conformaly coated, Volvo will insist on this for any ecu that has perminant power.

The above happened mine, if you search my threads I think I posted a pic. I replaced the corroded reset chip, cleaned pcb and away she ran for the next 18 months till I sold it.

funk-you

DublinDilbert wrote: »

Is there any water marks or corrosion on the old ecu?

Drain hole in the bottom of the ecu enclosure gets blocked and fills with water. Cpu reset generator is at bottom of pcb and doesn't like getting wet. The e90 ecus i've seen are even conformaly coated, Volvo will insist on this for any ecu that has perminant power.

The above happened mine, if you search my threads I think I posted a pic. I replaced the corroded reset chip, cleaned pcb and away she ran for the next 18 months till I sold it.

Nope, no signs of corrosion etc. I took it out and gave it a once over before it went to the garage but no joy. Ah well, my pocket is a little lighter but my baby is happy out again driving like a dream.

-Funk

ofcork

Special Circumstances wrote: »

??? Be the least of your worries if the ecu went?

I believe its an ecu controls these as well quoted major money to replace anyway.