[lexfury]

Hi guys,

I have a 2006 E90 with the problem that I can central/remote lock all 4 doors, but the rear doors won't *unlock*. I can see the latch jiggling a bit but doesn't go up. I need to open the rear doors from the inside which shoves the latch up on first pull then door opens no problem from inside/outside.

Just after a sanity check before I buy new actuators - I've swapped fuses 56 and 57 for 20A ones (one of them looked a bit burned) but it hasn't fixed the issue, is this definitely going to be a lock actuator problem, and there's nothing else like some other fuse, programming etc that could cause it at this point?

Thanks!

[gbalthrop]

Originally Posted by lexfury

... 2006 E90 [320d?] with the problem that I can central/remote lock all 4 doors, but the rear doors won't *unlock*. I can see the latch jiggling a bit but doesn't go up. I need to open the rear doors from the inside which shoves the latch up on first pull then door opens no problem from inside/outside. I've swapped fuses 56 and 57 for 20A ones (one of them looked a bit burned) but it hasn't fixed the issue, is this definitely going to be a lock actuator problem...?

Attached to NEXT Post are two ScreenPrints of ISTA "Central Locking Drives" SSP wiring diagram for your 320d, showing Left Side & Right Side of same large circuit. Also attached is a ScreenPrint showing the 'Lines ID' of each of the wires and the two Rear Door Locking Motors.

Although the JBE (A4010a) diagram shows TWO different "multiple" relays, it does NOT show what the function of each is, and HOW the relays are wired to the door lock Motors at each of the 4 doors. The Lines ID suggests to me that one of the two relays (in each set?) is the "Locking Relay" and the other is the "UNlocking Relay". You could get some clues on internal wiring by testing with ONE of the fuses F56/ F57 removed. Different fuse for Front than for Rear? Which fuse supplies Boot Lock & Fuel Filler Flap?

If there is NO Fault Code in the JBE Module Fault Memory, related to Central Locking, I would do the following:
1) Test EACH Rear Lock independently, by disconnecting ONE of the two rear locks and testing the remaining lock to see if it both Locks & UNLOCKS. It is possible that ONE of the Actuators is preventing the other from working. It is rather unlikely that BOTH Actuators have failed at same time. Same applies for Boot Lock & Fuel Filler Flap Lock, depending upon which fuse supplies those components.

2) I would then test for Voltage in the MER (Blue) and MZS (Black) lines when unlock is pressed to see how the two doors compare. You may have a wiring, connector, or even relay issue.

These suggestions are based SOLELY on looking at the ISTA wiring diagrams, and NOT on any personal testing. Please let us know what you find.
George

[gbalthrop]

Attached ScreenPrints for 2006 320d Central Locking Drives, as discussed in prior post.
George

[The Nightman]

In case you aren't aware, a pair of front actuators are much cheaper and will also fit the rear (but you will lose the child lock function):

https://www.fcpeuro.com/products/bmw...mw-51217272999

Unfortunately there doesn't seem to be a discounted pair of rear actuators. You could try this repair:

https://www.e90post.com/forums/showthread.php?t=1022395

[lexfury]

Originally Posted by gbalthrop

Attached to NEXT Post are two ScreenPrints of ISTA "Central Locking Drives" SSP wiring diagram for your 320d, showing Left Side & Right Side of same large circuit. Also attached is a ScreenPrint showing the 'Lines ID' of each of the wires and the two Rear Door Locking Motors.

...

George

Thanks for this great info George. Yes, it is a 320d.

There was no electrical issue - the actuators themselves were faulty (at least, the 'unlock' functionality, locking was fine). I swapped them for new ones and now all working.

[lexfury]

Originally Posted by The Nightman

In case you aren't aware, a pair of front actuators are much cheaper and will also fit the rear (but you will lose the child lock function):

https://www.fcpeuro.com/products/bmw...mw-51217272999

Unfortunately there doesn't seem to be a discounted pair of rear actuators. You could try this repair:

https://www.e90post.com/forums/showthread.php?t=1022395

Thanks - I'm in the UK and went for a set of eBay from a parts shop, £35 each. Chinese replicas I assume, but I'm not fussed if they don't last as long as OEM - only needed to pass MOT, I don't even use the rear doors

[StradaRedlands]

Originally Posted by lexfury

Thanks - I'm in the UK and went for a set of eBay from a parts shop, £35 each. Chinese replicas I assume, but I'm not fussed if they don't last as long as OEM - only needed to pass MOT, I don't even use the rear doors

I have replaced with both used BMW and Chinesium ebay parts... both have worked fine after the swap!