Central Locking won't unlock

[gprocket]

1991 164L.

After removing and reinstalling the interior door and trunk panels the central locking will not unlock. This is regardless if whether I use the console button, the key or the front door button (post). No problem with the locking it. I assume something I did during this R&R process caused the failure but everything looks right to me so far.

If I put a continuity tester on the central button I notice that when I call for locking the tester glows for a short period and then goes out (and the doors have locked). When I call for unlocking I get nothing and the doors do not unlock.

I don't have an electrical schematic so I'm flying blind here but I don't see any mention of relays in my shop manual - just a fuse which is fine. I suspect that there is a computer module of some sort that controls these functions. True? Should I be looking for that and if so, where? I did tried disconnecting the battery to allow the system to reset but that had no effect.

The only other issue is that the driver's side rear door lock solenoid was jambed and would not allow locking or unlocking. I swapped in a spare solenoid and it works properly now (except unlocking). I didn't notice any signs of shorted wires so I doubt this caused any damage to the system but it is an odd coincident none-the-less.

Any thoughts?

[Alfisto Steve]

Quote:

Originally Posted by gprocket 1991 164L. After removing and reinstalling the interior door and trunk panels the central locking will not unlock. This is regardless if whether I use the console button, the key or the front door button (post). No problem with the locking it. I assume something I did during this R&R process caused the failure but everything looks right to me so far. If I put a continuity tester on the central button I notice that when I call for locking the tester glows for a short period and then goes out (and the doors have locked). When I call for unlocking I get nothing and the doors do not unlock. I don't have an electrical schematic so I'm flying blind here but I don't see any mention of relays in my shop manual - just a fuse which is fine. I suspect that there is a computer module of some sort that controls these functions. True? Should I be looking for that and if so, where? I did tried disconnecting the battery to allow the system to reset but that had no effect. The only other issue is that the driver's side rear door lock solenoid was jambed and would not allow locking or unlocking. I swapped in a spare solenoid and it works properly now (except unlocking). I didn't notice any signs of shorted wires so I doubt this caused any damage to the system but it is an odd coincident none-the-less. Any thoughts?

[gprocket]

Thanks for the schematic. Where is the door lock control module physically located? I did try both door actuators and the result is the same - no unlock.

The fleet came with a set of Cardiscs - but do you think I could find the disk with the wiring diagrams?? I have the shop manual but I am surprised it does not have a schematic... Anyway, I will break down and buy the cardisc disks. I have them for the 105's and really do feel lost without them.

Thanks for the tips!

[Alfisto Steve]

Quote:

Originally Posted by gprocket Thanks for the schematic. Where is the door lock control module physically located? I did try both door actuators and the result is the same - no unlock. The fleet came with a set of Cardiscs - but do you think I could find the disk with the wiring diagrams?? I have the shop manual but I am surprised it does not have a schematic... Anyway, I will break down and buy the cardisc disks. I have them for the 105's and really do feel lost without them. Thanks for the tips!

[gprocket]

You know I just remembered that my hard copy manual is for a '94. Would that make any difference as far as the locks are concerned?

So as far as logic is concerned, am I right in thinking that when you push the unlock button (or pull the actuator or turn the key) a momentary signal is sent to the module which then evaluates the state of the system before returning 12VDC to the lock motors to release? What needs to be what in order for the locks to open? Is there anything with the alarm system?

Thanks,

Rich

[Alfisto Steve]

Page 182 in 94 wiring diagrams looks similiar to pg 566 in 91 wiring diagrams for power door locks but there are some differences.

Along this line my 164 driver's door lock stopped locking all the doors yesterday. Key locks only driver's door manually but will unlock all the doors after I lock the doors with passenger door lock or inside door lock switch. So I must have a failed door lock actuator P11.

[gprocket]

Today I ran accross the Wiring Diagram and Diagnosis book (all 593 pages and 20 lbs of it) in my big pile of unorganized stuff. What a great publication! Does the cardisc include this book?

Anyway, in addition to the diagram it has the description of operation and tests. I now understand that when the button is pushed for locking a momentary 12VDC signal is sent to N11 via pins 4 & 5 which energizes the lock motors via pins 1 & 2. When the unlock is pushed, the polarity is reversed through the circuit. The front door actuators act in a similar fashion except that N11 gets a signal through pins 2 & 3.

Since the locking and unlocking use the same exact circuitry and the locking function works, all the wiring and connections must be functional. The culprit in my case must be the Control unit N11. I will verify this today as time permits.

Now for your issue, does the lock/unlock work properly with P10 & B20 and unlock only for P11? Is so, I would concur that P11 is bad. If P10 works then N11 is good since P10 & P11 share the same pins 1 & 2. And since P11 work in the unlock function that validates the wiring and such. So the only thing left is the switch itself.

Isn't the switch buried in the locking mechanism? Is it replacable on its own or does the whole mechanism go?

I think I like my problem better than yours...

[gprocket]

Knowledge is power: It was indeed the N11. I swapped control units with a spare and bingo - lock and unlock.

So without the help of this forum I would have had to take this in to my friendly Alfa service specialist and spent what, $200 - $300...

[Alfisto Steve]

Quote:

Originally Posted by gprocket Today I ran accross the Wiring Diagram and Diagnosis book (all 593 pages and 20 lbs of it) in my big pile of unorganized stuff. What a great publication! Does the cardisc include this book? Anyway, in addition to the diagram it has the description of operation and tests. I now understand that when the button is pushed for locking a momentary 12VDC signal is sent to N11 via pins 4 & 5 which energizes the lock motors via pins 1 & 2. When the unlock is pushed, the polarity is reversed through the circuit. The front door actuators act in a similar fashion except that N11 gets a signal through pins 2 & 3. Since the locking and unlocking use the same exact circuitry and the locking function works, all the wiring and connections must be functional. The culprit in my case must be the Control unit N11. I will verify this today as time permits. Now for your issue, does the lock/unlock work properly with P10 & B20 and unlock only for P11? Is so, I would concur that P11 is bad. If P10 works then N11 is good since P10 & P11 share the same pins 1 & 2. And since P11 work in the unlock function that validates the wiring and such. So the only thing left is the switch itself. Isn't the switch buried in the locking mechanism? Is it replacable on its own or does the whole mechanism go? I think I like my problem better than yours...

[U5tabil]

Anyone knows where the G168 connector is located (from the manual)? I can't seem to find it. It only says Connector, front doors to left front door wiring.

[Alfisto Steve]

Quote:

Originally Posted by U5tabil Anyone knows where the G168 connector is located (from the manual)? I can't seem to find it. It only says Connector, front doors to left front door wiring.

[U5tabil]

Yes i think but not sure. I have the manual and i have that drawing, but it doesn't say where it is located. And to be honest there are ALOT of connector under there.

[Alfisto Steve]

Quote:

Originally Posted by U5tabil Yes i think but not sure. I have the manual and i have that drawing, but it doesn't say where it is located. And to be honest there are ALOT of connector under there.

[U5tabil]

Quote:

Originally Posted by Alfisto Steve Check the color codes of wires in manual in that connector and look for wires behind side panel going to door. It is probably one of the connectors in corner of dash neae fuse panel. What system in door are you trying to troubleshoot?