1996 Civic Door Lock Failure

I have a 1996 Honda Civic EX Coupe.

Both automatic door locks stopped working.

There’s only one switch on the driver’s side to lock/unlock both doors.

I first checked the interior and exterior fuses which were all good.

I then took the door switch out and tested for power.

There are 3 wires going into the switch.

The center black wire has no power regardless of switch position.

Both outer wires have power while the switch is in the center position.

One outer wire is 10.4 – 11 volts depending on the car being started or not.

The other outer wire is 23-24 volts depending on the car being started or not.

When I move the switch up one of the outer wires is dead.

When I move the switch down the other outer wire is dead.

I removed the door panel and tested the harness going to the driver side actuator.

There are 4 wires in this harness.

Only 1 of the outermost wires has power at any time. The other 3 wires are always dead.

The one wire was reading about 4.2 volts and if I switched the switch up or down it would lower to about 4 volts each time.

Everything in the car is OEM from the factory except the alarm system. I’ve had the alarm for about 4 years without a problem. I could always lock/unlock the door with the remote.

Now, neither the remote nor the door switch will do anything with the locks.

The alarm still works fine otherwise.

The power windows work fine also.

At this time there’s no radio installed. It’s been out for awhile and everything was working fine.

I am not at all familiar with the wiring or how this system works. I assume since both doors are not working it’s not an actuator problem.

Does anyone have a diagram and/or voltages that I can check for at the switch and wires going to the door actuator?

If anyone has any ideas or opinions based on the information above I’ll greatly appreciate it. I don’t know if there are any relays I need to check/replace, maybe the alarm is screwing up the voltages to the door lock (it’s a cheap alarm), or maybe it’s the electronic box in the driver’s door?

I can provide pictures or diagrams if needed.

I guess I need to know the proper voltages I should be seeing at the switch and actuator harness before I can go any further.

Thanks

Sorry I'm new here and didn't know I couldn't paste from Word.

I have a 1996 Honda Civic EX Coupe.
Both automatic door locks stopped working.
There’s only one switch on the driver’s side to lock/unlock both doors.
I first checked the interior and exterior fuses which were all good.
I then took the door switch out and tested for power.
There are 3 wires going into the switch.
The center black wire has no power regardless of switch position.
Both outer wires have power while the switch is in the center position.
One outer wire is 10.4 – 11 volts depending on the car being started or not.
The other outer wire is 23-24 volts depending on the car being started or not.
When I move the switch up one of the outer wires is dead.
When I move the switch down the other outer wire is dead.

I removed the door panel and tested the harness going to the driver side actuator.
There are 4 wires in this harness.
Only 1 of the outermost wires has power at any time. The other 3 wires are always dead.
The one wire was reading about 4.2 volts and if I switched the switch up or down it would lower to about 4 volts each time.

Everything in the car is OEM from the factory except the alarm system. I’ve had the alarm for about 4 years without a problem. I could always lock/unlock the door with the remote.
Now, neither the remote nor the door switch will do anything with the locks.
The alarm still works fine otherwise.
The power windows work fine also.
At this time there’s no radio installed. It’s been out for awhile and everything was working fine.

I am not at all familiar with the wiring or how this system works. I assume since both doors are not working it’s not an actuator problem.

Does anyone have a diagram and/or voltages that I can check for at the switch and wires going to the door actuator?

If anyone has any ideas or opinions based on the information above I’ll greatly appreciate it. I don’t know if there are any relays I need to check/replace, maybe the alarm is screwing up the voltages to the door lock (it’s a cheap alarm), or maybe it’s the electronic box in the driver’s door?

I can provide pictures or diagrams if needed.

I guess I need to know the proper voltages I should be seeing at the switch and actuator harness before I can go any further.

Thanks

infinkc wrote:

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do you hear the relays clicking in the blue box in the door when you press the switch? those are the door lock relays in the 96

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No, I hear absolutely nothing.

Should it be obvious or do I need to put my ear to the box?

I am fairly positive there is no sound at all when I move the switch.

KarTuneMan wrote:

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If you can touch the relays and work the switch....you can "feel" them clicking

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Just put my hand on the blue box in the door?

and if they aren't clicking?

I can't check them right now because I am at work and the car's at home, but I don't think they are clicking.

Also, why would one wire on the switch read 23-24 volts? Is this normal or am I doing something wrong with the voltmeter? I grounded it to the door and touched each of the 3 wires on the switch to get the readings.

infinkc wrote:

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https://repo.jackmoves.com/albums/album206/Lock_wiring_3.png

here is a link to the schematic for the power locks, its a fairly easy diagram to follow. yes you should feel or hear the relays click, you might just disconnect it for a few minutes and replug it in, i had a problem with mine and it seemed to reset itself, was caused by the locks being constant locked. as for the 23-24 volts i have no clue why you are getting a reading that high

oh btw the blue box is easy to open, you can check the circuit board easily for burnt traces/caps

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Thanks for the diagram. I'll try unplugging it first to see if that works. Any chance that you know what the voltages should be to the wires on that diagram? I am definitely getting some very strange readings.

If unplugging it doesn't work I'll open it up and take a look.

Thanks

infinkc,

Thanks for all the valuable advice.

I unplugged the motor control unit for a few minute like you said and it works like a champ.

The voltages were screwed up because I had the voltmeter on the wrong setting. I changed and went off your wiring diagram and everything was 12 volts.

The strange thing is that my car was totalled and I covered it and let it sit for about 2 years. I had the entire back half of the car replaced and I'm now getting it all back together. I have pictures of the before and after if you care to see them. It was a pretty amazing body job.

Anyway, the power locks worked for a awhile after getting it back on the road and just stopped. It would have made more sense if they didn't work at all after the car was parked for 2 years.

It's working now and I'm very grateful for your advice. You saved me a lot of time.

I guess I spoke a little too soon.

After connecting it back it worked for a brief time and stopped. Each time I disconnect and reconnect it will work for a short time and quit. I took the circuit board out of the blue case and there is one resistor burnt. There is a small burn mark on the board around the resistor but the traces "appear" to be ok.

There's an electronic parts house around from my job. They have 100's of resistors and other parts. I'll try to replace it and see what happens.

In case that doesn't work does anyone know a good source to order a door lock control for a 1996 Civic EX?