’94 civic toad ai606 locking problem

I've recently been having issues with my passenger door not locking on my Honda Civic HB. My drivers door is working fine, upon locking the passenger door manually unlocking works as per normal! Just doesn't seem to want to lock via the 606.. It's been fitted to the standard honda central locking and the actuator for the 606 is on the drivers side. The passenger side normally locks as a result of the drivers ide locking?? It was professionally fitted although the fitter is 400miles away so looks like this will be a diy :( Any advice would be appreciated!!

Sounds like one of three things 1) Does the passenger dor lock motor still work? Check by closing both doors then pressing the lock button inside driver's door. If so, 2) make sure the added motor in the driver's door is pulling the rod all the way. 3) Factory relay inside driver's door has failed, check fuses first.

The passenger door does unlock automaticly if locked with a key but wont unlock with the other door. I've had the drivers door panel off today and can confirm the rod is being pulled back far as it'll go, is there anyway to test the drivers door relay other than getting a new one?? I've checked the main fuses and they all look okay, would the toad fuse be on the toad unit it's self?

Assume "with key" you meant from the driver's door in which case my guess is the unlock side of the factory relay in the driver's door,  first check the lock motor outputs by flipping the lock,  the motor wires should both sit on ground,  then the lock will go live on locking for just under 1 sec, flip unlock and the unlock  motor wire should do the same. I think lock colour is WHITE/ red, unlock WHITE/ green, I' assuming this is a 3 door coupe, Japanese build not 5 door  Swindon build.

I was referring to by locking the passenger door via the external lock using a key or via the manual lock inside.. I'll grab a multimeter and see what i can findout :), if theres no signal getting to the passenger door on locking i'm guessing that would be the relay? Should have checked that first really! It's a jdm 3 door hatch