Doors will lock, but won't unlock with switch or key fob ?

David Neibert

SCCoA Admin
Drove my 91 today and made a stop on the way to work, when I tried getting back into the car using the aftermarket alarm key fob it chirped and flashed the lights, but didn't unlock the car. I tried it a few times with no luck then used the key to get in. The arm and disarm function of the alarm is working. The switch on the DS door and the key fob will lock the doors, but neither will unlock them.

I don't know enough about how the aftermarket alarm system activates the solenoid or whatever is used to lock and unlock the door, to determine if the problem is with the door switch or with the solenoid that moves the locking mechanism. Which one do you guys think is causing the problem ?

David
 
There is likely a relay attached to the alarm system that triggers the door lock solenoids. My guess is either the relay failed, or a fuse for the relay has failed, or the alarm system control signal has an issue.

Could just be a connector fell off. Though where it would be I'm not sure.
 
There is likely a relay attached to the alarm system that triggers the door lock solenoids. My guess is either the relay failed, or a fuse for the relay has failed, or the alarm system control signal has an issue.

Could just be a connector fell off. Though where it would be I'm not sure.

If it was the relay, wouldn't the door switch still work ? If it was a fuse for the relay I wouldn't expect the fob to be able to lock the doors.

David
 
Most aftermaket units have a internal relay in the module that sends a trigger signal to the stock lock wire and another to the unlock wire.

Mike is on the right track..Try unlocking the door with the switch on your doors to eliminate the possibility of the cars mechanism and narrowing it down to the aftermaket alarm.
 
Most aftermaket units have a internal relay in the module that sends a trigger signal to the stock lock wire and another to the unlock wire.

Mike is on the right track..Try unlocking the door with the switch on your doors to eliminate the possibility of the cars mechanism and narrowing it down to the aftermaket alarm.

Ricardo,

I did try unlocking them using the door switch...NO GO. The DS door switch will lock them and so will the key fob, but neither will unlock them. I have to use the key if outside and the door handle if inside to unlock them. Just went out and tryed the PS side door lock switch and it will lock and unlock both sides, so I guess that eliminates the solenoid.

Is it possible that a bad door switch on the DS side could, prevent the remote from working too ?

David
 
o.k.. you had too many words.

you have an aftermarket alarm with aftermarket keyless entry. Door switch will lock the door but not unlock the door. Aftermarket keyless entry will lock the door but not unlock the door.

That points to a failure in the power door lock actuator for the factory, as the key fob probably is just energizing the factory electric lock mechanism (via a relay) You could test by sending power to actuate the unlock at the switch. From the diagrams I could find, it appears the actuator grounds to the chassis, and has two wires feeding it. One is power to lock, one is power to unlock.

The switch has a center power feed, and at the top and bottom corners is either the lock/unlock or ground.

Actuators are available aftermarket, but they are pricey. Considering how rare they fail, a used one may be a better deal.
 
Ricardo,

I did try unlocking them using the door switch...NO GO. The DS door switch will lock them and so will the key fob, but neither will unlock them. I have to use the key if outside and the door handle if inside to unlock them. Just went out and tryed the PS side door lock switch and it will lock and unlock both sides, so I guess that eliminates the solenoid.

Is it possible that a bad door switch on the DS side could, prevent the remote from working too ?

David

Your problem is in the car components not the aftermaket alarm. I assume your alarm or keyless entry is wired to the drivers side switch.
 
o.k.. you had too many words.

you have an aftermarket alarm with aftermarket keyless entry. Door switch will lock the door but not unlock the door. Aftermarket keyless entry will lock the door but not unlock the door.

That points to a failure in the power door lock actuator for the factory, as the key fob probably is just energizing the factory electric lock mechanism (via a relay) You could test by sending power to actuate the unlock at the switch. From the diagrams I could find, it appears the actuator grounds to the chassis, and has two wires feeding it. One is power to lock, one is power to unlock.

The switch has a center power feed, and at the top and bottom corners is either the lock/unlock or ground.

Actuators are available aftermarket, but they are pricey. Considering how rare they fail, a used one may be a better deal.

Mike,

I just went out and tried the passenger side door mounted switch, and it will lock and unlock both sides, so I don't think it's the acuator. From what you and Ricardo have described it almost sounds like it has to be a problem with the driver's side unlock power wire between the relay and the acuator/solenoid. This assumes that the unlock power wire from the passenger side switch is differnt, because it is working.

Can a bad driver's side switch prevent the key fob from unlocking it ?

David
 
o.k.. you had too many words.

you have an aftermarket alarm with aftermarket keyless entry. Door switch will lock the door but not unlock the door. Aftermarket keyless entry will lock the door but not unlock the door.

That points to a failure in the power door lock actuator for the factory, as the key fob probably is just energizing the factory electric lock mechanism (via a relay) You could test by sending power to actuate the unlock at the switch. From the diagrams I could find, it appears the actuator grounds to the chassis, and has two wires feeding it. One is power to lock, one is power to unlock.

The switch has a center power feed, and at the top and bottom corners is either the lock/unlock or ground.

Actuators are available aftermarket, but they are pricey. Considering how rare they fail, a used one may be a better deal.

Mike he mentions that the passenger switch unlocks the car so i think the actuator is ok. The problem must be with the unlock ground on the drivers door....same wire that the alarm taps into.
 
Your problem is in the car components not the aftermaket alarm. I assume your alarm or keyless entry is wired to the drivers side switch.

I think you are correct. Since I don't have a clue how the alarm system was wired in, I'm going to try changing the driver's side switch and go from there.

David
 
Mike he mentions that the passenger switch unlocks the car so i think the actuator is ok. The problem must be with the unlock ground on the drivers door....same wire that the alarm taps into.

Any idea what color the DS unlock ground wire is, or where on the car they would have tapped into the wire ?
 
The wire runs down into the kick panel. If you remove it you might be able to see where the guys who wired the alarm tapped into it with some vampire taps. I have not seen anyone run the alarm wires up thru the door into behind the door panel. They take the shortcut and tap at the kick panel where your hood latch lever is. I dont know the color sorry.
 
It pretty much has to be a bad switch on the driver's side because the system is a simple reversing polarity. The alarm relays are inserted between the driver's switch and the actuator. When the relays are not in use they rest at continuity which is what allows the passenger side switch to work. When the relays activate they send alternately power and ground to the actuator, power via the alarm fuse, and ground via the switch. Since the alarm will lock the doors, it can't be an alarm fuse. Since the drivers side actuator actually works when fed from the passenger switch, the only part remaining in the circuit is the driver's side switch and the ground that is on the other side of the switch. However, since the driver side switch will lock the doors that means the ground is good and subsequently it can only mean that the driver side switch is bad.

Either that or I forgot everything I learned about door lock systems. :)
 
It pretty much has to be a bad switch on the driver's side because the system is a simple reversing polarity. The alarm relays are inserted between the driver's switch and the actuator. When the relays are not in use they rest at continuity which is what allows the passenger side switch to work. When the relays activate they send alternately power and ground to the actuator, power via the alarm fuse, and ground via the switch. Since the alarm will lock the doors, it can't be an alarm fuse. Since the drivers side actuator actually works when fed from the passenger switch, the only part remaining in the circuit is the driver's side switch and the ground that is on the other side of the switch. However, since the driver side switch will lock the doors that means the ground is good and subsequently it can only mean that the driver side switch is bad.

Either that or I forgot everything I learned about door lock systems. :)

Sounds pretty convincing to me...I'll change the switch.

David
 
Can a bad driver's side switch prevent the key fob from unlocking it ?

perhaps, as Dave D described. You can test the wires pretty easy. pull the switch off the plug. The center connector on the plug should be 12v and hot with key off. One of the bottom two and one of the top to will be common to ground, the other two open. Jumper the center to the non-ground pins and the actuator should pop. If it does... then your switch is bad.

I can't recall if you can just take the passenger switch and swap it with the drivers side. Also, you can get at all this without removing the door panel. just pop up the panel over the switches.
 
perhaps, as Dave D described. You can test the wires pretty easy. pull the switch off the plug. The center connector on the plug should be 12v and hot with key off. One of the bottom two and one of the top to will be common to ground, the other two open. Jumper the center to the non-ground pins and the actuator should pop. If it does... then your switch is bad.

I can't recall if you can just take the passenger switch and swap it with the drivers side. Also, you can get at all this without removing the door panel. just pop up the panel over the switches.

Thanks for the info.

David
 
I have seen the wiring at the door A pillar cause issues like this from all the bending and folding over the years.... But it is likely the switch...
 
Sounds like the car I unsafe and shouldn't be on any public streets again, brin it to me and Tony and I will dispose of it properly.



:)


In my limited electrical experience I'd have to agree with Dave change the switch and it should be good.
 
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