Battery Dies Unless I Pull Main Relay ICV Stays Engaged

[MadDogMontana]

1999 328is

I have been troubleshooting this for sometime now. Mysterious battery drain of about 2.3 amps unless I pull the main relay. The ICV stays engaged after I turn the car off. I hear it buzzing when I pop the hood. Hours can pass by and when I plug the relay back in I hear the buzzing of the ICV. Its a pain to start, often times I get no start unless I charge the battery up over 12.6v and clear any fault codes with the OBDII scanner. Just replaced the battery so its not that.

The relay is extremely hot after I run the car and you can feel heat in the wiring harness leading to the fuse box.
I have checked the grounds in the engine bay and everything seems fine. Where else are grounds located?

Could it be something with the ECU? I had a leak into the ecu box that was fixed and we replaced the ecu about 12 months ago.
Could it be a couple of exposed wires in the harness touching somewhere? There seems to be a lot of electrical tape/splicing going on there.
I spoke to a mechanic who dismissed my assumptions about wires rubbing or the ecu and he wants to go down the ignition switch path but I don't know how much I trust that thought. Once I get the car started it runs and drives fine, but getting it started is a hassle to say the least.

pls help.

thank you

[Eric93se]

You have to replace the ICV and it would be wise to replace the relay. Unhook the battery for now.

[ed323i]

It seems all injection electronics remains active: DME in active mode (not sleep mode), ICV, MAF sensor, coils, etc.. Quite a high drain on the battery.

Most logical explanation would be bad DME relay (look it up in google images: DME relay E36 328i). You can swap it with another relay of the same color (double check part number) to test if the problem stops.

You can test ignition switch by removing the black panel below the steering wheel column and removing the big connector from the ignition switch. If everything turns off immediately, it's the switch.

If those two steps don't fix it, you'll have to do some more troubleshooting. The DME relay is a bit complex. When you turn on ignition, the DME gets power, then it sends a ground signal to the DME, which then activates all the ignition electronics and turns the DME into active mode (it's actively listening for a signal from the crank sensor and will start injecting and sparking once it gets a good signal and enough RPM).. Look up the Bentley manual and start tracing / measuring wires.

But chances are that the first two steps will fix it already.

Good luck!

[MadDogMontana]

Thx,
I have tried replacing the relay, have already purchased 2 new relays so it has to be something else. Will test the ignition switch later.

It seems all injection electronics remains active: DME in active mode (not sleep mode), ICV, MAF sensor, coils, etc.. Quite a high drain on the battery.

Most logical explanation would be bad DME relay (look it up in google images: DME relay E36 328i). You can swap it with another relay of the same color (double check part number) to test if the problem stops.

You can test ignition switch by removing the black panel below the steering wheel column and removing the big connector from the ignition switch. If everything turns off immediately, it's the switch.

If those two steps don't fix it, you'll have to do some more troubleshooting. The DME relay is a bit complex. When you turn on ignition, the DME gets power, then it sends a ground signal to the DME, which then activates all the ignition electronics and turns the DME into active mode (it's actively listening for a signal from the crank sensor and will start injecting and sparking once it gets a good signal and enough RPM).. Look up the Bentley manual and start tracing / measuring wires.

But chances are that the first two steps will fix it already.

Good luck!

[bluptgm3]

I think the clicking is most likely the fuel vapor vacuum purge valve.


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[MadDogMontana]

Its more of a constant buzz sound coming from under the intake manifold.

I think the clicking is most likely the fuel vapor vacuum purge valve.


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[ed323i]

That's the ICV.. When the DME is on, it will constantly run the ICV, causing it to make a buzzing sound..

[MadDogMontana]

That's the ICV.. When the DME is on, it will constantly run the ICV, causing it to make a buzzing sound..

So how do I get it to stop running? Bad ecu? Bad wiring harnesses? Bad ignition switch?

[ed323i]

Bad ignition switch is most probable cause (very easy to test, just remove the black panel from the steering wheel column and remove the connector from the ignition switch; swapping it is quite easy). Next, bad wiring (as you wrote it was tempered with; a lot more work, especially if you're not experienced with electronics/wiring). Next, bad DME (easy to swap, but will need EWS resync, but not too high probability that the DME is the cause).

Good luck!

[MadDogMontana]

Bad ignition switch is most probable cause (very easy to test, just remove the black panel from the steering wheel column and remove the connector from the ignition switch; swapping it is quite easy). Next, bad wiring (as you wrote it was tempered with; a lot more work, especially if you're not experienced with electronics/wiring). Next, bad DME (easy to swap, but will need EWS resync, but not too high probability that the DME is the cause).

Good luck!

Thx, so a little more info,

I have to put the key in the ignition and turn 3/4 of the way, let it sit for a few seconds and try to start it . this usually works, if I just put it in and turn I never get it going. not sure what that means.

thx again

[spyderg0d]

If your icv buzzez then its bad. Period. If it buzzes with car on or off. The icv becomes internally shorted and will buzz whether or not the dme is powered. Happens frequently on all bmw models that take this icv. E36, e46, includeing the cross manufacture models lile Volvo and Volkswagen.

[MadDogMontana]

If your icv buzzez then its bad. Period. If it buzzes with car on or off. The icv becomes internally shorted and will buzz whether or not the dme is powered. Happens frequently on all bmw models that take this icv. E36, e46, includeing the cross manufacture models lile Volvo and Volkswagen.

So I plugged in an old ecu that I had I swapped out a while ago and the buzzing didn't happen,

[Kraftwerk]

This is interesting to come across right now.... I too found a completely flat battery recently after clearing codes, hear the 'buzzing' from the engine bay, when the ignition was off.. (!) etc. So maybe, just maybe, I am in the same boat as you MadDogMontana... Will go down the same rabbit-hole and let you all know what I find.

[MadDogMontana]

This is interesting to come across right now.... I too found a completely flat battery recently after clearing codes, hear the 'buzzing' from the engine bay, when the ignition was off.. (!) etc. So maybe, just maybe, I am in the same boat as you MadDogMontana... Will go down the same rabbit-hole and let you all know what I find.

bought an ews delete ecu on ebay, plug n play. swapped and worked. no buzzing, starts right up. some CE codes come up but I think they are unrelated. cps and charcoal evap.

make sure you pull your main relay or disconnect the neg battery terminal. I prefer pulling the relay because I think the battery disconnect causes the ecu to reset and the car wont run as well until you put a few miles on it. not sure how this works exactly.

[ed323i]

Thanks for the feedback. Interesting to see that the DME can cause this.. It probably has a shorted ground connection, sending a permanent ground to the DME relay, which then turns on, and which in turn turns on all electronics under the hood.

[Kraftwerk]

Nice that your mystery is solved, congrats. Thanks for following up and thanks for everyone for the great info here. Again, I will let you know what I find. My car is a '96 M3 but I suppose there are a lot of similarities... relays etc.

[spyderg0d]

You sure it was the icv buzzing and not the dme relay.

[MadDogMontana]

The relay would engage when I plug it back in but the ICV was staying on or buzzing under the intake manifold. When I swapped the ECU the buzzing stopped along the battery drain issues