2000 Toyota Hiace Van, Lock/Unlock Using Viper 3400v Keyless Entry

Hi, I have a 2000 model Toyota Hiace van with factory fitted key operated central locking.

I believe Toyotas use negative trigger outputs to operate the door locks so I have connected the green (lock) and blue (unlock) outputs from the Viper 3400v control module to the Toyota door lock control relay (D10) inputs (the same wires that provide the signal when the drivers door key is operated (green/black and green).

If I lock using the drivers door key then press the unlock on the Viper key fob the doors unlock.
If I then press the lock button on the key fob the Viper relay operates (one click from internal relay) but the doors do not lock (solenoids not operating).
If I manually lock a door by hand and press unlock on the key fob it unlocks again.

If I unlock using the drivers door key then press the lock on the key fob the doors lock.
If I then press the unlock button on the key fob the Viper relay operates twice but the doors stay locked (solenoids not operating).
If I manually unlock a door by hand and press lock on the key fob it locks again.

The installation manual isn't clear on when a 451M relay is required or how to wire it in if it is indeed required.

Any assistance would be very much appreciated.

Do you have a switch for the lock/unlock at the driver window controls?

The original key operated central locking still works, I didn't disconnect any of the original wiring. The van has manual windows so no switch where there would be on newer cars with power windows. I would have thought that the switch that operates when I use the key works the same as the switch that you are talking about. At this stage all I can assume is that there is something more technical happening inside the factory control relay module.

So a quick update. I spoke to an auto electrician and showed him what it was doing. He couldn't explain why it was doing it but said in his experience virtually all Viper units needed the separate relays. Initially I tried wiring the relay in so either the original drivers door key or the Viper key fob would lock/unlock all of the doors but whenever I pressed a button on the key fob it blew the fuse (something inside the Toyota module was causing a dead short). The end result was I have disconnected the original Toyota door lock control relay (D10) and am just using the Viper unit with the 451M relay. So using the Viper operates all doors and using the key just manually operates each door lock.

First off I'm glad you have it sorted.

I can't say I have had the same experience as that auto electrician with Viper units. I've installed Viper systems without the use of additional aftermarket relays where low current (<250ma) computer signaling or OEM relay control was all that was needed.

As for your central locking system, I believe the problem lies in the fact that that door lock switch isn't momentary. I suspect the factory locks operate whenever you manually move the door lock button and change the states of the switch from unlock to lock or vice-versa. Two ways to interface with the factory locks, without disabling the factory functionality, would be to either use an aftermarket power door lock actuator to move the drivers door lock for the Viper thus allowing indirect control of the factory central locks OR you can cut the factory switch wires and insert a relay that will make or break the connection upon command from the Viper unit (the relay will make the connection at all times except when the Viper is commanding the locks).

Thank you so much for this info. What you have said makes sense and I think I will go with your first option. Cheers.