Hey everyone, so I've got an 83 pickup with CA emissions setup. On the vacuum diagram under the hood there is a part listed as VCS (vacuum control switch?) Does anyone know what this is and what it does. I don't seem to have it and while the truck runs I'd like to try and get it as close as possible to where everything should be. Any help is appreciated, thank you.

 

It likely stands for vacuum control switch. The years before and after yours show a similar part in the same location but label it a VCV (vacuum control valve). The 1980 year looks to not have it at all. '81 and '82 list it only for Cali 4x4 vehicles and it's completely gone by 1985, which has fewer valves and switches in general.

Whatever it was, don't worry about it. If an inspector ever notices it's gone, congratulate them on their obscure knowledge of Japanese emissions parts rendered obsolete 33 years ago.