E39 530i DME Failure (How to diagnose a faulty or water damaged DME as the cause of crank no start)

[@steveappleton6236]

Hi. Very useful video. My 530i was left for 1 week while we went on holiday, and was running ok when parked. I had experienced occasional strange events - like a bulb warning light for a front fog light bulb which worked fine, and if I put the main beam on and then off, it cleared the fault. At one point my headlights would be on main beam unless I selected main beam on the light stalk controls, which was wierd, but then it just stopped doing it. So maybe that was a sign of what was to happen next. While we were away, there was some very wet and windy weather back home - like, the rain came in horizontally. When I went to start her up, it ran ok for a short while and then started to misfire. I limped home and parked up, then tried to check for possible causes. The misfire remained, and when I put the lights on I could hear something from the engine bay, like a clunking sound. I'm thinking that the DME might be water damaged as you've described. Sporadic stupid events which cleared up on their own could just have been because the DME dried up. Just 1 question, is the DME box always under the right side air filter - or would it be different for right hand drive? I can't see whether your 530i is right or left hand drive 🙂 Many thanks again

[@bavhaustv9795]

Glad to hear the video helped! This vehicle is LHD so I’d make the assumption that on your vehicle the dme box will be on the opposite side of the steering shaft. I may be wrong but it isn’t all too difficult to verify. -Mike

[@andersonchimukono8498]

You help me a lot

[@bavhaustv9795]

@@andersonchimukono8498 happy to help! -Mike

[@andersonchimukono8498]

Great job ❤❤❤

[@bavhaustv9795]

@@andersonchimukono8498 thanks! 🍻

[@dwightvoeks9970]

Great post. I'm experiencing this now. Electronics gone haywire. Will start and run when cold but will eventually die and not restart. No communication with Autel, Foxwell or generic scanner. My issue might be moisture and cracked solder joint because it will run for about 15 minutes and most functions seem to work. Sending mine in for repair.

[@bavhaustv9795]

Sorry for the late response! What ended up being the solution?

[@whichdoctor4858]

I can hear the DME relay clicking like that and my temp gauge pegs to the red when the engine is cold. I put in a new double temp switch and it still has the issue. I unplug the connector to the DT switch and it will start occasionally and sometimes just cranks. The OBD reads correct temperature when it starts. When it does go wrong, the OBD just doesn’t talk and the relay clicks like a fan. I’m thinking my DME is dying!

[@bavhaustv9795]

The DME has an influence on all of those things you have listed and you shouldn’t throw any more parts at it before inspecting the dme for damage

[@whichdoctor4858]

@@bavhaustv9795 thanks for the advice. What I did try is replacing the power blue relay to the DME which was dead cheap. Then I added an earth connection to the relay board as the earth wasn’t great and now my car starts fine and the power relay never flutters anymore. No more pegging of the temp gauge. Thanks for the tips! I still do have had a power drain 0.69A for a couple of years when the car is asleep. Flattens my battery after 5 days. I checked the fuses/systems to death and nobody else could find the cause of draw either. Ironically the blue power relay to the DME was hot. It was the only thing left to check. I unplugged the power relay and my current draw was reduced from 0.69A to 0.03A on my 530i. I’m going to check the power feed to the relay/ignition switch and also the DME for corrosion. There was a spot of water in the white plastic DME box. Can the DME raise sleeping amps to 0.69A?

[@bavhaustv9795]

@@whichdoctor4858 weirdly enough I think this car also had a parasitic draw

[@PillaPrynce024]

Good man. Please do you have to a link or a source to get a new dem programmed? I will be greatful thanks

[@bavhaustv9795]

Type in “dme repair” on Google and choose a service! They’ll be able to guide you to the best solution. -Mike

[@anirudhkashyap7551]

What was the final fix for this car? My car has the exact same issue. Do I need to just replace the DME?

[@bavhaustv9795]

Sorry for the late response, yes another dme was paired to the ews and that’s what repaired the car

[@austenolson9855]

You replaced a fuel pump without checking for pressure?

[@bavhaustv9795]

I think the owner tried replacing the fuel pump himself prior to the car being brought to us but the install was botched so we installed a new one for him after that previous one was misdiagnosed and then damaged

[@correctionslag5715]

where did you go to get it cloned?

[@bavhaustv9795]

Sorry for the late response, we work with RPM in Canada

[@sidnarciso4872]

Why not clean relay contacts and retry, or replace relay

[@bavhaustv9795]

There was clear water damage to the DME