Door Lock Problems

Created: 8/14/03

Last updated: 

Author/source: DML

There is a simple fix for this problem, simply completely remove the front
lock rod (parts man. #43). In some cars there is a very narrow adjustment
tolerance that will allow both latch mechanisms to operate simultaneously.
The door lock system will work perfectly with just one rod. As long as the
rear latch is locked there is no way to open the door without unlocking the
door. I have used this procedure for the past 17 years with no ill effects.

DeLorean Help

----- Original Message -----
From: "Travis Goodwin" <>
To: <>
Sent: Wednesday, February 13, 2002 12:07 PM
Subject: [DML] Driver's side door lock

> I've got a problem. My passenger door lock sticks when I try to unlock the
> door. It happens most often when I lock and unlock the door from the
> with the key. The problem lies in the front right door lock. When I go to
> unlock the door, the lock mechanism sticks a little before releasing.
> Sometimes it will let go, but most often it will not. I have already
> replaced the RH front lock mechanism and the RH door lock rod.
> I'm wondering if anyone has had this problem before and if someone has a
> possible solution. I'm hoping to fix it for good and never have to get
> that door again.

From: "checksix3" <>
To: <>
Sent: Saturday, June 29, 2002 11:14 PM
Subject: Door Lock Module

The stock lock module can be made very reliable with a few simple
mods, all of which Martin has mentioned. The switches and linkages in
the doors must also be adjusted properly if you want total confidence
in the system. (Btw, Martin is right about the wiring, the red wire
only powers the solenoids and not the module.)

If you're still concerned about burned out solenoids, here is a
simple and effective fix that I implemented when I rewound my
solenoids and modified the module: Change the CB to a manual
resettable one of a much lower rating.

The solenoids pull 10 amps per coil (either locking or unlocking)
for a total of 20 amps. This happens for less than 1 second during
operation. Since the solenoids are intermitant duty, they will fry
in a certain time. (say 30 seconds for the sake of this explaination.)

Use a thermal CB of 5 to 7 amps. (I like the Potter & Brumfield
W58 series or the Texas Instrument "klixon" series, both readily
available.) Since these are thermal CBs, the specs are something
like: "trip at 150% in 30 minutes or trip at 400% in 15 seconds."
(examples only, you get the idea.)

We can use this hysteresis to our advantage by using a much lower
rated 5 or 7 amp CB to replace the stock breaker. You will be able to
cycle the locks normally without nusiance tripping. If you continue
to repeatable cycle the locks in a short time period (why would you
do this?), the CB will trip after 10 cyles or so and must be manually
reset. If your solenoids remain energized due to a fult in the lock
module, this CB will take them off line in 15 seconds or so. (You can
still open the car with the key or the handle if this happens.)

 In testing, my 5 amp P & B CB tolerates appox 10 rapid cycles before
heating to the point of tripping, yet I have never had a single trip
during "normal" lock/unlock operations. The CB rating can be played
with as long as you don't exceed the time for solenoid burn up. I
used 30 seconds for this, which I think is generous. (I would not go
above a 10 amp CB.) Since bimetallic thermal CBs are pretty much
immune to transients, thats not an issue here.

This way you will never burn up your solenoids or drain your battery 
if the module fails, which it should never do if you accomplish the
other simple mods Martin mentioned.

Lockzilla? Its OK, but why do many assume what you can do yourself is
inferior? This ain't rocket science folks. But its your choice and
your money, I don't care either way.

From: "checksix3" <>
To: <>
Sent: Sunday, June 30, 2002 11:41 AM
Subject: Lock module

>>A failure mode (not sure how common) of the lock module (in
addition to the relays welding themselves together and burning up the
solenoids)are the 1000uF electrolytic capacitors inside the module.
If either of these fail short the locks actually still work pretty
well, but the steady-state current draw of the module goes up enough
to draw the battery down in a day or so, but NOT enough to blow any

Right you are Dave. The caps should be replaced as part of the
upgrade, as electrolytics are prone to failure with age and heat due
to their construction technique. Btw, if they truely short they will
blow something (either themselves or something else), the problem you
describe is probally leakage. As for blowing fuses, that feed doesn't
even seem to be on one, at least from my initial inspection.

>>Disconnecting the large red wire won't help, you would have to
unplug the multi-conductor plug to avoid this issue.<<

Right again, although DMC Joe can be excused for believing otherwise
because the schematic shows what he stated. (Btw, even the Zilla
schematic is rife with errors.) The print shows the violet wire
(brown on the car side of the connector) feeding from the load side
of the solenoid breaker. This is incorrect, at least on my car. 

From where it gets its feed is unknown to me at this time (its not on
*any* of the fuses in my car) but you can bet any direct short in the
module will quickly fry it or the wiring. This should be addressed as
it could be a fire hazard and is another example of just how poorly
the car is wired.

Another advantage of using a lower rated CB to feed the lock
solenoids is that the violet (brown) wire can be fed from this
breaker also. This would provide overcurrent protection for the
module and wiring where none seems to exists now. Another advantage
is that installing a pullable CB like the P & B series W31 toggle or
W23 pull type (instead of the W58 I mentioned) one can easily switch
off all the power to the locking system for storage. If not this, the
violet wire feeding the module needs to be put on a small fuse

There are many things that need to be done to the car's electrical
system (things that go beyond the well known fixes) to make it less
of a toaster in the making. For example, adding a fusable link as
close to the main source as possible was one of the first things
I did.

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