Print Page | Close Window

1984 Chevrolet C10, Alarm Door Lock Not Working

Printed From:
Forum Name: Car Security and Convenience
Forum Discription: Car Alarms, Keyless Entries, Remote Starters, Immobilizer Bypasses, Sensors, Door Locks, Window Modules, Heated Mirrors, Heated Seats, etc.
Printed Date: September†29, 2022 at 3:06 PM

Topic: 1984 Chevrolet C10, Alarm Door Lock Not Working

Posted By: clarkchriston
Subject: 1984 Chevrolet C10, Alarm Door Lock Not Working
Date Posted: August†01, 2022 at 5:39 PM

I have a 1984 C10 that Iím helping my son build. We are not mechanics or electricians but we are making progress. We have gutted and re-wired the entire vehicle (except for the Stock Lock Relay) and everything works as it should. We are in the process of installing a Viper 3305V in the truck. Everything works great except the Door Lock function (Locks work great using the switches, just not from the remote). Iíve included a diagram of the Truck wiring and highlighted the routing for ease of following. From what Iíve seen the way I have it wired should workÖ..unless I need a relay (or 2) because the way the stock was ran back in 1984. Itís either I need relays, or possibly have a bad connection at the alarm system itself. As installed the alarm will arm and lock the door with the press of the remote but will only dis-arm and not unlock the door with the remote.

We double checked the door locks and they are negative pulse door locks. Both wires read 0, then 13.5 when the switch was depressed. We did this for the BLK/WHT, and LT Blue wires at both doors, and at our desired connection location behind the instrument cluster.

Again I suspect the issue is a need for adding relay, but Iíve also heard that some had issues with the connection location at the Alarm itself. Is there a way to check if the wires (from alarm) are receiving the signal from the remote to the brain and passing that along through the (blue and Green) wires to pulse at the connection point. Other people that have my same model year have wired exactly like I proposed and say they have no problems.

I also have a pretty good understanding of relays but with 2 locks connected together, and needing to add the wiring from the actuators I have a hard time figuring out the connections in my head. Iím also curious that if I add a relay or 2 do I then eliminate the single old (stock) relay I currently have. Any suggestions, diagram or schematic would be greatly appreciated.


Posted By: clarkchriston
Date Posted: August†01, 2022 at 5:43 PM
Vehicle is a 1984 Chevy C10. Alarm is pretty basic (Viper 3305V) with an added hood pin, no remote start.

Posted By: Ween
Date Posted: August†01, 2022 at 6:19 PM
The door locks are positive pulse. Orange/black is battery/constant power.
You'll need two relays to convert the negative door lock outputs of the Viper to positives.

Posted By: clarkchriston
Date Posted: August†01, 2022 at 6:43 PM
Thanks for the quick reply. Just after I posted this I realized (even tested as such) that it is a Positive Pulse System. I figured I needed the relays so thanks for confirming. One last I just leave the stock relay as is and tap into the switch Lock/Unlock wires (BLK/WHT, LT Blue) anywhere in line (to/from) the stock relay and leave the wiring for the actuators alone?

Posted By: Ween
Date Posted: August†01, 2022 at 7:13 PM
As long as the door locks are operating fine with the factory switches and relay, there would be no reason to change the system. And anywhere inline would be fine. Unless you are adding a priority/drivers door only unlock, the wiring from the relay to the actuators can remain intact.

Posted By: clarkchriston
Date Posted: August†03, 2022 at 10:49 PM
I wired the relays and still have the same issue. Alarm arms and unarms from the remote but only locks the door, the unlock does not work. The door locks work fine with the switches in the car. Switches, wires, and actuators are all brand new and working as they should. In hindsight it looks like the Viper 3305V works with Negative or positive pulse wiring so I probably didn't need the relays but it's still nice to take the load off of the old school factory relay.

The alarm arms and disarms from the remote so that tells me that the brain is receiving the signal from the remote controls. I know the locks are wired correctly. I decided to do a test on the 2 wires coming from the alarm brain. Blue wire is for unlock and green wire is lock. I hooked up my multi meter and set it to volts and put 1 probe on the green and 1 on the Blue. The other end of the wires are plugged into the alarm brain and nothing connected to vehicle lock wiring. Volts read about 3.2 I assume from circuitry in the alarm brain. When I hit the arm button on the remote the volts jump to 9.9. When I hit the unarm button on the remote the volts go to roughly 3.3, so basically the unarm is only sending a 0.1 volt pulse. I'm beginning to think maybe the viper alarm brain is bad or a connection inside is damaged. I can't think of any other reason I would get an increase of 9 volts when armed (and the doors lock) and only 0.10 volts (not enough) when unarmed and thus not triggering the actuator to unlock

Any other reason why the voltages would be so drastically different coming from alarm. Thanks in advance for any assistance.

Posted By: catback
Date Posted: August†04, 2022 at 11:04 AM
If you swap the Viper blue and green wires connected to the truck does the truck unlock when you press the lock button on the viper remote?

It does seem as though the viper module is not working. It's easy to damage the outputs by connecting them wrong (Shorting them to power/ground or connecting low current outputs to high current devices).

Posted By: clarkchriston
Date Posted: August†04, 2022 at 11:14 AM
Yes that's exactly what happens. Door will lock or unlock only from the lock button on the remote (nothing from the unlock). Switching the wires will still only send a pulse through the Green Wire (Alarm Lock Wire) from brain to which ever lock switch wires from truck (lock BLK/WHT, or unlock (LT Blue). Blue wire from alarm (Unlock wire) does not get a pulse at all regardless of which lock switch wire from truck it's hooked up to.

Print Page | Close Window