73-454

The tranny upsifts ok, When I punch the throttle at 60-70 mph the trany stays in 3rd. The vacume hose ok from engine to trany. Should I be looking at something else.

Aaron-74

There's a switch behind the gas pedal. Replace that. That same thing happend in our 73' all we did was replace that switch. It's right behind the gas pedal and up a little bit.

Blake-73

Had the same problem on my 73. Switch worked fine, but seemed like it was
coming in too late, so I put some tape around the lever to build it up to a larger diameter and it worked fine. A friend of mine had the same problem.
He put a piece of fule hose on his and it worked. Of course, a new switch would work as well.

Blake-73

73-454

Where is the switch, is it under the dash or on the floor behind the carpet.

lars

Blake & 73 -
The switch can be re-set so you don't have to do the rubber hose trick to it.

First, the switch is located right at the gas pedal. Little plastic and sheet metal switch with a plunger sticking out of it and a 2-wire connector. First, verify that you have power on the one wire with ignition in the "on" position. Then, slowly depress the switch plunger with your finger while checking for power on the other wire. When the plunger approaches the bottom of its travel, the wire should go "hot."

The plunger is self adjusting: The first time the gas pedal is fully depressed, the plunger "ratchets" down to to correct setting and stays there. If something later pushes the plunger further down, it will remain out of adjustment. You can bring the plunger back up to its initial position by depressing the plunger and letting it "flick" off your finger nail to pop up against its spring pressure. A couple of flicks like this, and the plunger will suddenly pop all the way up. Once it's popped up, slowly and softly depress the gas pedal to the floor. This will put the switch plunger in the correct position for proper kickdown operation.

redwingvette

On the small block engines there are 4 wires that go to that switch, One set for the trans and one set for the cowl induction hood door. The orange wire goes to the trans. If you check the wire where it attaches to the trans and it has power there then you may need to change the silenoid in side the trans. to do this is as easy as changing the filter. After you drop the pan and filter you will see it, take it out and put the new one in and you should be good to go.


[Modified by redwingvette, 3:05 AM 12/31/2001]

Smokehouse69

On mine the orange wire was broken and shorting out on the case of the transmission. Transmisson wouldn't kick down and blew a fuse everytime I floored it.

Ron 75 L48

At what speeds should the tranny kick down when you stomp on the gas pedal? Mine will only kick down if I am around 40 mph. Is it suppose to kick down at any speed?

Ron 75 L48

ttt

:flag

andre77

Is it possible that I don't have a kickdown switch? I checked all over and still nothing. th350 :eek: :confused:

Chuck Gongloff

The THM 400 definitely has an electric "kickdown" while the THM 350 uses a mechanical rod like the old powerglide. The electric kickdown switch is located inside the car, above the gas pedal. The pedal linkage pivots in the middle. When you stomp the pedal to the floor the upper part of the linkage comes back...like a "see-saw". It is the upper part of the linkage that "hits" the lever on the switch when you punch the pedal to the floor. This is a fairly big switch, not easy to miss. Maybe yours is missing??? Lars is 100% on the money about re-adjusting the switch. As I recall, the vacuum modulator controls shifts during normal driving, while the electric kickdown is used at wide open throttle. Hope this helps. Chuck

lars

Andre -
Only the TH400 has a kickdown switch. The TH350 uses a kickdown cable attached to the throttle linkage. The cable is adjustable by releasing the adjustment tab, going to WOT, and then pushing the tabs back in.

andre77

Thanks, no wonder I could'nt find it. :crazy: