Door Locks "out of sync"

[ccurzio]

Good day, everyone. I'm having a minor yet annoying problem with the locks in my '81 and I'm wondering if someone has an idea about what's wrong and how to fix it.

Based on the way the locks currently work (or don't work, as the case may be), it's my assumption that unlocking one door will unlock both doors, whether you unlock it via key or by moving the lock switch on the inside of the door. On my car, it's a little different:

PASSENGER SIDE
Unlock: Both doors unlock.
Lock: Both doors lock.

DRIVER SIDE
Unlock: Both doors unlock.
Lock: Only the driver door locks.

So it would seem that whatever mechanism controls the locking of both doors on the driver's side is not functioning. Meaning, any time I get out of my D and I want to lock the doors, I need to manually lock both of them.

Any ideas?

[Spittybug]

Sounds like the wiper arm on the switch inside your driver door needs adjusting.

[DMCMW Dave]

Burned out solenoid in the passenger door. When you are actuating the driver door you are moving the linkages manually, i.e. the solenoid is not really necessary.

For a better test, open the cover of the lock module and activate the relays one at a time BY HAND. (With the doors both closed or the latches tripped). Now you will see what really works and doesn't, and this will eliminate the wiper switches from contention. If you do this and both doors lock and unlock, now you can look at the switches or wiring.

[ccurzio]

Burned out solenoid in the passenger door. When you are actuating the driver door you are moving the linkages manually, i.e. the solenoid is not really necessary.

For a better test, open the cover of the lock module and activate the relays one at a time BY HAND. (With the doors both closed or the latches tripped). Now you will see what really works and doesn't, and this will eliminate the wiper switches from contention. If you do this and both doors lock and unlock, now you can look at the switches or wiring.

Sure enough, it looks like the solenoid is shot. I figured this might be the case, but I had no idea how to test it.

I popped open the lock module and flipped both relays. The passenger door doesn't respond.

Great tip! Thanks, Dave.

[Spittybug]

Now you know why Dave is the Delorean professional and I'm not!

[BigBenb84]

Since the original question has been answered, I'd like to throw in my problem since its similar.

-Both doors lock in sync no matter which door's switch done or outside key. All good there!
-Unlocking...neither door's switch activates the unlock sync, nor does the outside key.
-if I take off the cover of the (original) lock module and tap the relays by hand, they both unlock & lock. So they work.

First I thought it was the wiper switches in the doors, but they are contacting and shiney copper. And both failing only on the unlock portion...rare, eh?

I think its something right on the DLM, like its not getting the signal to "activate unlock switch".

[Ron]

...
I think its something right on the DLM, like its not getting the signal to "activate unlock switch".

Pick a point on the Brown-Pink wire near the relay and jumper it to a good ground.
If the doors unlock, the problem is from there back toward the switches (This wire simply branches to both switches.)
If they do not unlock, the problem is from that point on into the relay or the unlock half of the relay itself is probably shot.

[David T]

A damaged solenoid may work but not well and require WAY too much current. If you have any doubts about the coils then they probably need to be replaced or rewound. There is a good pictorial on rewinding them. All it takes is some time and a roll of magnet wire (not expensive and enough to do 6 solenoids). Do both. Add a 15 A fuse to the wire that comes off the circuit breaker to the lock module to prevent damaging the solenoids again.
David Teitelbaum

[BigBenb84]

Pick a point on the Brown-Pink wire near the relay and jumper it to a good ground.
If the doors unlock, the problem is from there back toward the switches (This wire simply branches to both switches.)
If they do not unlock, the problem is from that point on into the relay or the unlock half of the relay itself is probably shot.

I grounded said wire where I circled in red. Nothing happened. Then I grounded on the other side of that diode/capacitor(?) where I circled in yellow and the doors unlocked.
7166 7167

So you think I narrowed it down to that diode/capacitor or no? (I don't know which it is) What does it do?

[Ron]

I grounded said wire where I circled in red. Nothing happened. Then I grounded on the other side of that diode/capacitor(?) where I circled in yellow and the doors unlocked.
7166 7167

So you think I narrowed it down to that diode/capacitor or no? (I don't know which it is) What does it do?
Sounds right to me...
That is a diode. Current should flow through it one way, like a check valve for liquids, out of the end with the white band (red circle)... Since you grounded the yellow end and the doors unlocked, there is power there 'waiting' to pass through the diode. But when you grounded the red end, it seems power was not getting through it, so it must be burnt open internally.
Use a meter with a diode check.
Or, you can carefully remove it and check it with a meter. Put it on ohms and it should basically read very high (or infinite) one way and (near) zero the other. (It will read high both ways if we're correct.)
Or, remove it and run it in series with a small bulb, which should light one way and not the other. (Neither way will light if we're correct.)

[BigBenb84]

You think the fact that half of it is missing has anything to do with it? I assume it should be cylindrical.

7171


Might as well ask now...you happen to know what type I need? I know radio shack has them, I can just solder another one on?

[Elvis]

Wow, I've never seen a diode failing like that in the DLM.
And I updated MANY of them so far - between 30 to 50 !

Install a 10A fuse in the fat red wire. if it burns you know that at least one
solenoid is bad.

For a quick test you can bridge that diode ( let's call it Diode D5), the other input
doesn't have one either. Very early modules don't have them at all.

But the question is - how could that diode be destroyed like that ? This device only
sees a very small current of (if original) 12mA. It needs several amps or mechanical force to kill it like that !

You can install any diode you can find, 1N4002 or up to 1N4007 are OK, a 1N4148 will do it, too. if it fails like that again you know there is something bad.

Whily going to radioshack I suggest you get the parts to update that module, how to's are around. replace the relays ! these original suckers stick together and burn the solenoids ! I saw it a few weeks ago when I updated five modules and thought - hey these relays in this one module look like new, I leave them there. While testing it in the car I suddenly couldn't unlock the doors anymore and after a few seconds the 10A fuse burned and released me !
Replace those relays !!! and don't use the original ones anymore (I think they are BOSCH - they really don't like the application here !!! )

I highly recommend everybody to install that 10A fuse !!!!

And while in there, invest some more cents and do the current saving update.
I have like 10 years of positive experience with that so far.

instructions can be found on the DMCNEWS list.

Elvis & 6548

[Ron]

You think the fact that half of it is missing has anything to do with it? Yeah...it can't keep the smoke in it like that ;-)

Use one of the replacement diode(s) Elvis mentioned above.

[BigBenb84]

...and done. It WORKS! What else to do on Christmas morning. Replaced the two diodes with ones Elvis said from Radio Shack. My first soldering job..didn't do to bad.

7432 7433

And now I can fully enjoy my wings-a-loft.


http://www.youtube.com/watch?v=vuzHeDPBBVg

[Elvis]

Did you install the 10A fuse ?

No kidding the original relays will stick together and burn your solenoids - and lock you
inside the car !


and yes - good job, great so see it works :-)

[BigBenb84]

Did you install the 10A fuse ?

No I didn't, don't tell anyone.

[Ron]

...and done. It WORKS! ...
Good Job :thumbup2:

[sdg3205]

What is the value of the diode I'm missing here? I've got some 1N4007 on hand.

Doors lock but will not unlock. I've run the lock n latch procedure several times. Manually manipulating the relays will make the locks work perfectly. This was hidden by the wire loom but something is clearly burnt and gone.

http://img.tapatalk.com/d/14/02/02/yma9ete3.jpg

[jawn101]

What is the value of the diode I'm missing here? I've got some 1N4007 on hand.

Doors lock but will not unlock. I've run the lock n latch procedure several times. Manually manipulating the relays will make the locks work perfectly. This was hidden by the wire loom but something is clearly burnt and gone.

http://img.tapatalk.com/d/14/02/02/yma9ete3.jpg

Dave - that's so weird. That diode had broken off on my car too. What's the deal with that?

I don't remember what it was unfortunately. I replaced it when I rebuilt my lock module on someone's recommendation (likely Dave M or Elvis) but with what.... :dunno:

[sdg3205]

Yeah! It looks like it blew up and just disappeared!

This is off 3922, a local new owner. I'm going to take mine from 3205, put a 10 amp fuse in the power lead and see how it works.

There may be more wrong with 3922s DLM than just the one invisible diode.

Volker, the owner of the car found that the circuit plan says 1n8119. We'll solder it in and see what happens

[Elvis]

For the 25th time in this forum - DO NOT REPLACE THAT DIODE !!!


It's an overvoltage protection - that burns in almost every car !

Its function as overvoltage potection is useless, but it works fine
to eventually light up your cigarette !
I've seen some that burned the PCB almost thru !

50 modules later and not a single replaced over voltage protection
diode - all cars work fine and no risk of fire from that ECU anymore !

What should be updated in that ECU can be found here in the forum
many times.

[sdg3205]

Jesus man, it may be common knowledge for someone who's done 50 of these things, but for someone who's encountered this for the FIRST TIME it seemed obvious. Try to be a little more condescending next time.

I won't replace the damn diode.

[Elvis]

I know what you mean, but the knowledge has been posted so often... I use the search myself very often.


BTW :

25012

http://www.asos.com/Elvis-Jesus/Elvis-Jesus-Back-To-The-Future-T-Shirt/Prod/pgeproduct.aspx?iid=1672652&cid=0

:biggrin::biggrin::biggrin:

[sdg3205]

I know what you mean, but the knowledge has been posted so often... I use the search myself very often.


BTW :

25012

http://www.asos.com/Elvis-Jesus/Elvis-Jesus-Back-To-The-Future-T-Shirt/Prod/pgeproduct.aspx?iid=1672652&cid=0

:biggrin::biggrin::biggrin:

I did, which is how I found this thread and other threads. I've only been an owner for about 4 years but I've spent thousands of hours on this forum and this is the first I've heard of the explosive diode :)

At any rate, my question has been answered and I thank you.

Please tell me you wear that shirt!

[Elvis]

No but I keep it in my car :-P