bmw door locks

Hey guys, so I'm looking for some guidance on the door locks on a BMW. I am working on two, a 2007 X3 and a 2003 Z4. Both seem to have the same setup.

I understand the door locks are type B. I can get the locks to operate by the wire listed in the diagrams. The problem is, there is no distinct signal to lock/unlock the car (because of the single button that controls the locks). Installed is an Avital 5303. The system likes to send a 'lock' command when it's remote started. This feature cant be turned off with the 5303, even with a BitWriter.

I found the wires that control the locks via the lock cylinder in the door. There are two, a WHITE/ yellow (unlock), and a black wire (lock). These wires stay grounded, and spike to +12V when you turn the key. So, I thought I could wire a relay to send 12V on the respective wire, but it's blowing fuses (up to 20A). They don't blow right away, it maybe takes a solid second. But before it blows, the motors sound extremely weak, almost like it doesn't have enough power. I'm kind of scared to put a 30A fuse in it for fear of zapping something.

What I'm trying to accomplish here is to have a distinct lock signal, and a distinct unlock signal. I know it's possible, but I can't figure out what I'm missing. Anyone ever worked with these types of locks and deciphered this?

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No question is stupid or not worth asking. You were once a noob, right? :)

I'm no bmw expert but if you're sending + on a negative trigger wire, that's no good. The arm/disarm wires should be negative trigger. Which wires from the avital are you using to control doorlocks?

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Advanced

dasbogie wrote:

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I'm no bmw expert but if you're sending + on a negative trigger wire, that's no good. The arm/disarm wires should be negative trigger. Which wires from the avital are you using to control doorlocks?

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You're correct on that. But some circuits rest on ground till they get a positive signal (my Saab does this too). I'm using the blue and green (-) outputs.

I would think if the circuit is being shorted, the fuse would blow immediately and furiously. But it's taking a second and the fuse is melting. I was thinking of trying with a 30 because that's what the car uses on the door motor circuit. I'm just scared to in case BMW does things differently.

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No question is stupid or not worth asking. You were once a noob, right? :)

Go to the loom coming into the vehicle at the DKP blue/red lock and close windows, WHITE/ black unlock, both NEG.
I never use that switch, it's one wire MUX by the way, I believe 200 ohms, also if the owner then uses the factory key, you're all out of synch.

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Amateurs assume, don't test and have problems; pros test first. I am not a free install service.
Read the installation manual, do a search here or online for your vehicle wiring before posting.

howie ll wrote:

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Go to the loom coming into the vehicle at the DKP blue/red lock and close windows, WHITE/ black unlock, both NEG.
I never use that switch, it's one wire MUX by the way, I believe 200 ohms, also if the owner then uses the factory key, you're all out of synch.

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I knew you'd find me!

I'll have to try this again. I did meter these wires as well and they spiked to 12V also. I figured it either had to be this pair or the pair I listed above.

What if this doesn't work? O.o Should I tell the guy he needs to trade it in?

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No question is stupid or not worth asking. You were once a noob, right? :)

Howie, are these usually a twisted pair? There's a WHITE/ black sitting at .73V and there's a blue/red twisted with a red that's wound tight. I looked at the plug coming through the firewall and see a blue/red but no BLACK/ white.

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No question is stupid or not worth asking. You were once a noob, right? :)

Not at all, on the X5, you're looking for the driver's door switch you'll find them there.
On the Z4, the loom from the door joining the main vertical loom where bulkhead meets kick panel.
I've never yet tested a BMW with a DMM, use a test light e.g. Snap-On CT-4F, the incandescent bulb swings enough current to trigger the locks.
Noobies use all this expensive test equipment without knowing what they're looking for
Joking aside if it's a twisted pair it's either speaker or CAN or K-Bus, avoid!

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Amateurs assume, don't test and have problems; pros test first. I am not a free install service.
Read the installation manual, do a search here or online for your vehicle wiring before posting.

Alright, I'm on site now. This is the 2007 X3.

On the door lock motor,
Black
Blue/brown
WHITE/ yellow
WHITE/ black
Brown
BROWN / grey / YELLOW

On the window switch,
Grey/red
RED / green
BROWN / red
Brown

That twisted pair of red and blue/red are going to the airbag! Good thing I didn't test those lol. I figured they were data, but each car's different.

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No question is stupid or not worth asking. You were once a noob, right? :)

I found these wires at the general module. Hooked up, and got nothing.

The owner said the factory remotes stopped working a couple months ago. The key cylinder in the driver's door still powers the locks though. I'm not sure if the remote issue could be effecting the wires.

I checked all the fuses, and the only bad fuse was for the cigarette lighters. I tried to change the fuse, but it instantly lit off. I checked all the lighter sockets for coins and paperclips, but didn't find anything wrong with them. He said they never worked since he bought the X3.

Can you shed some light on whether this could be an issue? I wouldn't think it would, but I don't know much about BMWs.

The Z4 has a similar setup, I believe. I told him we can try that car over the weekend.

I really don't want to wire in the 5 wire lock bypass.

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No question is stupid or not worth asking. You were once a noob, right? :)

howie ll wrote:

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use a test light

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I never thought I'd hear you say that! lol


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No question is stupid or not worth asking. You were once a noob, right? :)

Using a test light is quicker, faster and more efficient and if the truth were known, most techies and pros still use them!
BUT you have to know where and when!
I have a pal who uses a power probe, I'm too scared to get one.
The 07 vehicle worries me, I'd have used a DB-ALL or similar for locks, lights and door triggers.

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Amateurs assume, don't test and have problems; pros test first. I am not a free install service.
Read the installation manual, do a search here or online for your vehicle wiring before posting.

But the dB-All isn't supported for the 07 X3...? At least not in the US. You think the BCM might be the same? I could try it and see what happens...

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No question is stupid or not worth asking. You were once a noob, right? :)

Yes, go to Xpresskit, top right, click on US, you'll get regions on top left, select Europe, then do the usual, you'll still need a "key in a box" though.

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Amateurs assume, don't test and have problems; pros test first. I am not a free install service.
Read the installation manual, do a search here or online for your vehicle wiring before posting.

Oops, not listed, I'm uploading the Directwire info right now, I'd either probe the wires at the lock or hit on the motor wires at the "general module" (5 wire).

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Amateurs assume, don't test and have problems; pros test first. I am not a free install service.
Read the installation manual, do a search here or online for your vehicle wiring before posting.

Go to Downloads/Manuals, key in BMW X3.

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Amateurs assume, don't test and have problems; pros test first. I am not a free install service.
Read the installation manual, do a search here or online for your vehicle wiring before posting.

howie ll wrote:

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Go to Downloads/Manuals, key in BMW X3.

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Well, I have 4 different diagrams. All but one tell me it's the yellow/red wire from the switch, and for both lock and unlock. The other says the WHITE/ black and the blue/red.

I have probed the wires at the driver's door lock, and found two that 'spike' to 12V, depending on lock or unlock, and they rest at gnd. The X3 also has the two step unlock (first time drivers, second time the other doors) from the key hole in the driver's door. I was hoping I could leverage this, since the factory remotes don't work. The locks will begin to move slowly if I attach +12V on them, but will eventually blow a fuse (I've only went up to 20A, but I think the fuse in the box is 30A).

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No question is stupid or not worth asking. You were once a noob, right? :)

Going to the switch won't give you comfort close.
Either probe all the wires going into the door, not the twisted pair or check at the window switch in the door; what you found are the motor wires.

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Amateurs assume, don't test and have problems; pros test first. I am not a free install service.
Read the installation manual, do a search here or online for your vehicle wiring before posting.