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Central Locking Switch Deterioration

bobxyz

bobxyz

Board Member
Joined
Aug 29, 2014
Location
Boulder CO
Since I'm posting pictures tonight, here's the central locking switch harness out of my '85 245 driver's door. The circular collar goes around the lock cylinder, and the black cylindrical one is part of the lock pull -- pull up extra and all doors (plus trunk/tailgate) unlock, push down extra and all lock.

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picture of installed collar (thanks volvogeek)
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and a picture from the web
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My central locking was originally inoperative due to the relay ground wires accidentally being left floating after a PO fan replacement. I re-grounded them but the locking was intermittent. The door lock and the pull-to-unlock were OK, but the push-to-lock caused both relays to click with no actual locking. Pulling the switches out of the door, I was amazed that they worked at all and weren't completely shorted out. The switches ground one of two relay wires (or two of two wires when shorted in my case).

I found a better lock harness at the salvage yard from a '93, but still needed to splice in good wires to the bare wires coming out of the lock collar. I was able to disassemble the lock collar and clean up the internals, but you'd probably do fine just spraying contact cleaner in through the gap and cycling the switch. The cylindrical lock pull switch seems glued together and I couldn't disassemble it.

The door harness goes through a 3-wire harness connector above the driver's left knee - red/green/black (Christmas sort of). If your locks are acting up, disconnect this harness or the relays/door solenoids may get stuck on and drain your battery.

If you replace your switches, look in the bottom of the door under the switches and you'll find a colorful collection of insulation crumbs.

-Bob
 
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Thanks, search failed me on this one. Central Locking vs. Auto Lock. Nice to have the repair pictures well documented.
 
Yep.
I've got the fuse (#8) for the central locking removed from the panel on my 92 240 right now.

There was a constant battery drain that was running the battery down.
I attached a DC amp meter in series with the positive battery cable and battery so that I could read the current being drained, I then starter removing fuses one at a time.

I had a constant 1 amp drain.

When I turned on the ignition switch the current climbed to about 8 amps that would slowly bleed down to about 1 amp constant....almost like the circuit was charging a leaky capacitor.
When I got to #8, I found the culprit.

While watching the amp meter, I started checking things that were powered thru fuse #8.....
When I got to the central locking, I found it.

The central locking works, except for the right front door. The lock button on the door itself is frozen, and can neither be pushed up or down.
When using the key to operate the system, the current draw would go to 8 amps and the other 3 doors would lock/unlock.
There is always a 1 amp current drain, even with the ignition switch turned off.
This drain is coming from the central locking system.

This is my next project on this car....repair the central locking.
I'm gonna start under the front passenger door panel.

That and install some Enviro-Safe refrigerant that was delivered yesterday.
3 cans for $19.95 delivered.
 
coalminer said:
When I turned on the ignition switch the current climbed to about 8 amps that would slowly bleed down to about 1 amp constant....almost like the circuit was charging a leaky capacitor.
Click to expand...

The reason it acts like that is there is a positive-temperature-coefficient thermistor disk in each of the lock actuator motors to protect it against extended locked rotor current. Looks like a small nickel sort-of. The thermistor heats up and the resistance rises to limit the current.

Now I wonder about your particular drain. Fuse 8 also supplies a thermal timer which allows you to have the courtesy lamp on for a half minute or so after you shut the doors. It is second in likelihood for the fuse 8 drain, but a close second in my experience. The thing that makes me wonder is you are able to use the central locking and still see the residual parasitic drain, where the problem causing it is the shorted wiring either enabling the lock or the unlock function. To fully rule that out (central locking) disconnect the door switches entirely by unplugging them just above your left knee.

keyless47.jpg
 
Thanks, I'll check that.

I assumed the problem was inside the right front door because the actuator doesn't move on that door when central locking is activated. That and the fact that the lock button on the door will not move either up or down. It seems like it is frozen in place or hung on something.

The delay on the interior light seems to function normally.
 
Thanks for the help, I am chasing a short coming from the fuse 8 circuit thats intermittent too and ill try looking into the door lock circuit.
 
coalminer said:
I assumed the problem was inside the right front door because the actuator doesn't move on that door when central locking is activated. That and the fact that the lock button on the door will not move either up or down. It seems like it is frozen in place or hung on something.
Click to expand...

That's a problem all right, and it is likely water got in the actuator, but not the cause of the battery drain. In other words, the passenger doors only receive the central locking commands and have no ability to control them or feed anything back.
 
cleanflametrap said:
That's a problem all right, and it is likely water got in the actuator, but not the cause of the battery drain. In other words, the passenger doors only receive the central locking commands and have no ability to control them or feed anything back.
Click to expand...


You are exactly right.
I removed the actuator from the right front door yesterday and the small operator motor inside the actuator was frozen. The rubber boot on top had a hole in it and water had been getting inside the actuator. The motor was rusty and frozen.

I've got a 91 model 240 parts car, and I'll get a actuator off of it.
I'll check it first before i remove the door panel.
I've also got a 85 245 parts car with central locking.
Are the actuators the same?

You are also correct about the current drain through fuse #8.
It is not caused by the central locking system.

The time delay works OK on the interior light.
Is it still possible for this timer to work and still be a drain on the battery?

I noticed that when I placed the fuse in #8 slot, I heard a low buzzing like a relay coil coming from behind the dash, slightly off center on the passenger side of the dash.
It shut off after a second or two.

Where do I need to look for this current drain?

Thanks a lot.
 
coalminer said:
The motor was rusty and frozen.
Click to expand...

lock6822.jpg


coalminer said:
Are the actuators the same?
Click to expand...

All are identical and reversible.

coalminer said:
Is it still possible for this timer to work and still be a drain on the battery?
Click to expand...

You have me there. This has never happened to any of my cars yet, and looking at the map I'm not sure how a heater could remain on in the timer and yet function to turn the light off after the delay. But it doesn't rule out intermittent short, perhaps between the wire in the heater wrapped around the bimetallic contact spring. All I know is when I suggest the delay relay is the trouble on the forums, the OP usually comes back and says replacing or removing the little delay unit -- looks like a fluorescent starter clipped to the brake pedal bracket on the right -- fixes the battery drain problem.

coalminer said:
Where do I need to look for this current drain?
Click to expand...

I think the green wire feeding the central locking is double-crimped with the one feeding the delay relay, so isolating it at the fuse panel is, well, invasive. I know someone who did it that way.

Might be easier to unplug the relay, meaning you have to pull the knee bolster and contort yourself under the dash. Or sit outside the car, and disconnect and separate all the wires on the door switch, insulate them from each other, and tie a piece of twine to the harness so you won't lose it in the pillar. Just a guess which is more appealing or effective.

lighting0832.jpg


lighting155.jpg



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Edit: Forgot to mention... I've only been talking the two heavy hitters on this symptom. Additional loads on fuse 8 are the trunk and glove box lamp, clock, and radio preset memory. And electric antenna. Some have said the trouble was an aftermarket radio. You can disconnect wires at fuse 8 until the drain disappears and see what remains working. Only problem is some loads are doubled-up on the terminals.
 
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stove said:
That works, but I just use like 5 coats of Liquid Electrical Tape.

Fixed dozens that way.
Click to expand...

Amazing. I see this posted often, and yet I've never purchased any of the stuff. My loss...

It really does seem like the obvious solution and effective on those silicone wires.
 
[Quote cleanflametrap] "Edit: Forgot to mention... I've only been talking the two heavy hitters on this symptom. Additional loads on fuse 8 are the trunk and glove box lamp, clock, and radio preset memory. And electric antenna. Some have said the trouble was an aftermarket radio. You can disconnect wires at fuse 8 until the drain disappears and see what remains working. Only problem is some loads are doubled-up on the terminals.[/QUOTE]

Fuse terminal #8 on my 92 model has only 1 Green Wire attached to the fuse secondary.
The wire must be paralled through all the components it powers.......Either that or there is a common splice terminal for the wires somewhere else.


I moved the radio to another fuse, The glove box light turns off properly when closed, the trunk light works properly, and the electric antenna is un-plugged at the motor.

I haven't had time to look at it today, but I'm gonna pull that door switch that you show and unplug the downstream tap, then check again for a current leak from the battery.
 
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