Door lock problem

[1990m3]

I've had 4 e30's and they have all had great central locking systems. Unfortunately the m3 my dad drives is not doing so well at the moment.

When you put the key in the door or trunk to lock everything, you can turn it to the lock position and the doors lock and then pop right back to unlock, regardless of which position you hold the key in.

You can try to deadbolt the lock or just lock it and the doors lock and then pop right back up.

Any advice on where to start looking? I'm a central locking system virgin to these cars

TIA
Dave

[Jeremiah]

More info is needed.

Do the dome lights work?
Does the gas door lock work?
Does the same thing happen when you use the lock on the pass side?
Has the car been in a accident?

[1990m3]

More info is needed.

Do the dome lights work?
Does the gas door lock work?
Does the same thing happen when you use the lock on the pass side?
Has the car been in a accident?

door lights - yes
gas door - no, all locks are inoperable
pass side lock - all locks act the same
accident - yes, front end.

[Jeremiah]

The Central Locking Control Unit has an Inertia Switch that activates on impact greater that 5g. Because of the cars accident history, I would swap out that unit with a known good one, as that’s likely your problem. All e30’s equipped with central locking use the same unit. It’s located behind the Left Front speaker (by the pedals).

Hope this helps.

Jeremiah

[jht3]

since it unlocks right after locking, i'm thinking there's an obstruction somewhere. if i don't close a door properly it'll do that same thing

so i'd check the fuel door, trunk, then the doors for proper closing

[UNHCLL]

since it unlocks right after locking, i'm thinking there's an obstruction somewhere. if i don't close a door properly it'll do that same thing

so i'd check the fuel door, trunk, then the doors for proper closing

You could also have a bad lock actuator. Sometimes they will do exactly what JHT is stating... sometimes they'll "lock up" in the locked position and you can't unlock the door without feeling like you're about to snap off the key.

-CL

[1990m3]

I'm planning to take off the drivers door panel this week and start poking around. They haven't worked since we bought the car about 2 years ago, but I gotta fix it before we get ripped off

[Reelizmpro]

You could also have a bad lock actuator. Sometimes they will do exactly what JHT is stating... sometimes they'll "lock up" in the locked position and you can't unlock the door without feeling like you're about to snap off the key.

-CL

I was thinking the same thing. Had a similar problem when I first got my car. Took a while to troubleshoot but after a new actuator and a few door pin terminals it was good as new. Try to find a spare actuator in known good condition to troubleshoot.

[fast325it]

My passenger side lock is down and will not come up - neither with the key or the interior door handle.

Can I remove the door panel with the door locked closed? Any diagnostic tips?

Thank you,

JB

[CourtM3]

had the same problem with mine when I took it out of storage. ended up being Keyless entry switch position wouldn't let the lock open

[F0Bman]

Yeah the plastic gears of the door lock motor might be stuck!

[fast325it]

Anyone have any suggestions for removing the door panel with the door closed?

I gave it my best to pull the lock up but it won't budge. I was attempting to turn the key in the door, was pulling up on the vise grip on the lock and my wife pulling on the inside handle - no luck. I'm afraid I might bend the linkages if I keep pulling on it.

Thanks,
John

[e30m3power]

Do yourself a favor and pick up a copy of the electronic troubleshooting manual. Has all the schematics from our cars in there. I have used it countless time. It's worth it's weight in gold for me.

[John Arnold]

They haven't worked since we bought the car about 2 years ago, but I gotta fix it before we get ripped off

Unplug the central control unit and lock the doors and trunk manually. You can lock the gas door manually by reaching through the punchout hole in the trunk lining and sliding the deadbolt.

Can I remove the door panel with the door locked closed? Any diagnostic tips?

It sounds like yours is electrically deadbolted. The deadbolt circuit is activated by a microswitch on the driver's lock mechanism. Remove the driver side door panel and check the microswitch. I'll bet it is stuck closed or shorted. You can replace it, or disable the deadbolt function by unplugging the microswitch.
If your doors won't lock from the driver side without the deadbolt switch, you need to replace the worn lock cylinder. These have a known defect where the ball bearing detent wears a groove into the housing. The replacement lock cylinders are much more durable, using a roller bearing instead of a ball.

[///mike]

When you put the key in the door or trunk to lock everything, you can turn it to the lock position and the doors lock and then pop right back to unlock, regardless of which position you hold the key in.

I have an E30 (325is) with exactly this same problem. You can actually feel the actuator "rebound" when you turn the key to the lock position. My guess is the same as others -- it sounds like the actuator has gone bad. I'll replace it when I get time.

I recently replaced the lock core on the driver's side of my car. Exactly as John Arnold described, the little lever at the end of the shaft wobbled all over the place on the old core. It had gotten to the point that, no matter how far I turned the key, it wouldn't lock.

I ordered the new core from a dealer. Using the VIN they can get you a core with the same key cut as OEM. I left the lock heater unplugged when I replaced the core -- there's no chance of a frozen lock here in Florida.