81 trans
Le Mans Master
Joined: Aug 2003
Posts: 7,720
Likes: 12
From: Chattanooga TN
Yep, the kit uses the brake switch and a vacuum switch to tell the converter to lock and unlock. You may also want to add an override switch so it doesn't continually lock and unlock under certain conditions.
Safety Car
Joined: Mar 2000
Posts: 4,077
Likes: 27
From: Northeast South Dakota
You can get a vacuum switch for an 80 Corvette and use that to make it work. You will have a 3rd gear pressure switch and a solenoid to lock the converter inside the transmission. If you add the vacuum switch you can wire a power circuit through the vacuum switch, then to the transmission and your lockup will work just fine. If you can find a wiring diagram for the lockup on an 80 vette you will see what I mean. The TH350C was used in the 1980 vette without the ECM. I copied this information years ago when I was doing a lot of work on the 81' ecm's for different people:
I have seen several threads asking how to wire up the lockup feature of the TH350C without having to purchase one of the expensive kits available from several sources.
The following are the AC Delco part numbers for the original components used for this transmission type.
Vacuum Switch - AC Delco # 212-331, GM # 14032087 ($35.31)
Brake Pedal Switch - AC Delco # D850A, GM # 25524845 ($11.32)
Vacuum Check Valve - AC Delco # 214-479, GM # 14020691 ($19.91)
The plug for wiring to the vacuum switch is not available new to my knowledge and I could not find one at the local salvage yard. To make the connection I soldered the wires directly to the connector lands on the switch using shrink tubing to provide some strain relief protection.
One of the wires from the vacumm switch goes to a keyed 12V source while the other wire goes to the brake switch.
The brake switch has four poles on it. Two are for the lockup function and the other two are for the tail light circuit. I had to figure out which was which was trial and error. Once you get that figured out and connect the switched 12v from the vacuum switch you will need to run aother wire from the other pole down to the solenoid switch on the transmission. The solenoid switch the rebuilder put in my trans only has one pole on it as the original is difficult to impossible to find. The replacement switch is from a later model GM lockup trans. It may be the 200R4 switch but not sure. If I get by the rebuilders shop again I will ask.
The other side of the vacuum switch consists of a male vacuum connection which I tubed to the intake manifold vacuum tree. The small check valve was inserted between the switch and the manifold.
That is it.
I tried sourcing these parts directly from the local Chevy dealer and was surprised at the high cost. I then call a local parts store call XL Parts. They were able to get the genuine AC Delco parts for LESS than half what the dealer wanted. Total parts cost was $66.54 plus tax. Your results may vary.
I mounted the vacuum switch on my firewall and to date the system has performed flawlessly.
I have seen several threads asking how to wire up the lockup feature of the TH350C without having to purchase one of the expensive kits available from several sources.
The following are the AC Delco part numbers for the original components used for this transmission type.
Vacuum Switch - AC Delco # 212-331, GM # 14032087 ($35.31)
Brake Pedal Switch - AC Delco # D850A, GM # 25524845 ($11.32)
Vacuum Check Valve - AC Delco # 214-479, GM # 14020691 ($19.91)
The plug for wiring to the vacuum switch is not available new to my knowledge and I could not find one at the local salvage yard. To make the connection I soldered the wires directly to the connector lands on the switch using shrink tubing to provide some strain relief protection.
One of the wires from the vacumm switch goes to a keyed 12V source while the other wire goes to the brake switch.
The brake switch has four poles on it. Two are for the lockup function and the other two are for the tail light circuit. I had to figure out which was which was trial and error. Once you get that figured out and connect the switched 12v from the vacuum switch you will need to run aother wire from the other pole down to the solenoid switch on the transmission. The solenoid switch the rebuilder put in my trans only has one pole on it as the original is difficult to impossible to find. The replacement switch is from a later model GM lockup trans. It may be the 200R4 switch but not sure. If I get by the rebuilders shop again I will ask.
The other side of the vacuum switch consists of a male vacuum connection which I tubed to the intake manifold vacuum tree. The small check valve was inserted between the switch and the manifold.
That is it.
I tried sourcing these parts directly from the local Chevy dealer and was surprised at the high cost. I then call a local parts store call XL Parts. They were able to get the genuine AC Delco parts for LESS than half what the dealer wanted. Total parts cost was $66.54 plus tax. Your results may vary.
I mounted the vacuum switch on my firewall and to date the system has performed flawlessly.
