blue_74

The passing gear in my '74 Vette w/a TH400 doesn't work. When I stomp it, all it does is open the 4 barrel, but the tranny doesn't even offer to upshift. I know that the TH400 has an electronically-controlled passing gear with some sort of switch under the dash, but where is the switch and what should I be looking for? The carbeurator is a new Edelbrock Quadrajet, but passing gear never worked w/the original Quadrajet either. Thanks.


[Modified by blue_74, 1:48 AM 9/23/2003]

dman535

The switch is mounted to the gas pedal. With the ignition on , you should get 12v at one side of the switch. Make sure that the connection to the transmission itself is in good shape.

goinbroke

Follow your accelerater pedal rod up under the dash. You should find the dentent switch mounted to a bracket. It should have two wires plugged to it. The switch has a "peg".........when the acc. pedal is pushed down the rod pushes the peg back activating the switch. In MOST cases the rod is making little or no contact due to the rod straightening over the years. You can either try to re-bend the rod or slip a piece of thick walled rubber hose over the switch peg making it's diameter bigger. The slide needs to travel about half way to work right. With the engine off and the key on reach up under there and pull the peg back.......you should hear a click from the solenoid at the tranny.

Mystery Machine

I had the same problem but mine turned out to be a fuse, check all your fuses and the detent switch as mentioned already.

desi

I had the same problem a few months back.... Here is my post. Please read all responses, it's got some very good info and tips. Basically, start with the low cost / easy items first. Check the fuse, kick-down switch, etc...
http://forums.corvetteforum.com/zerothread?id=611475

Mine turned out to be a loose kick-down switch. Just had to wrap some tape on the switch for better contact.

Good luck. :cheers: