We installed a 400 turbo in a 67 442. We have 12 volts to the transmission when the gas pedal is floored but it won't down shift when driving the car. We tested the ohms on the kickdown terminal on the 400 tranny and it has continuity.
Any ideas?
Thanks

 

Do you have headers on the car?

 

No headers.. It has a 455 tri carb engine with factory manifolds.

 

In the early days when I bought my 442 I put headers on the 455. They had to disconnect the kickdown so the headers would fit. I thought that might be it.

 

Are you still running the factory transmission control switch? Just making sure you have it connected to the downshift solenoid terminals and not the converter switch...

Assuming it was a Jetaway car and the Jetaway downshift was working before?

This is aggravating, but try wiring up a temporary switch. Wire it up to 12v, thru the switch and to the solenoid connector. Have a helper operate this switch by hand when you road test and see if it will downshift with this switch. If it does, you know the trans is working and it's a switch or adjustment issue. If not, it has to be the detent solenoid in the trans case or something else internal.

 

I read up on the 67 kickdown device and it does have 3 terminals. We are using the terminals that make contact when the pedal is on the floor. I am 100 percent sure it has 12v to the transmission solenoid when the gas pedal is on the floor. We checked it twice. I'm not sure what I would gain by rigging up a hand held switch but I know cars pretty well and weird things happen so we'll give it a go to confirm a problem. If it fails to kickdown, it looks like a problem with the solenoid.

 

You can usually hear the transmission solenoid 'click' if you listen closely with the key on, engine off and pedal (or pedal switch) depressed. TH400 transmission solenoid failures are really common. I think I had to replace the trans downshift solenoid in every TH400 I've had at some point or another.

 

Thanks Mike, There's hope Without pulling the tranny? We'll listen for the click. Great tip!!

 

I have a 69 442 with 400 engine and th400 trans. I found my transmission downshift switch unplugged at the gas petal. My assembly manual has a note "on cars with 35M38, tape downshift leads and connector back on main wiring harness with (specified) tape".

What does 35M38 mean? I am thinking that maybe the downshift switch was not connected because there is no electric solenoid connected to it.

Anyone know what is going on?

 

35 is the 3500 series of cars, which is the Cutlass line in the assembly manual. M38 is the RPO code for the TH350 (M40 was the TH400), so the TH400 kickdown wire was in every harness built, but obviously not used on the TH350 cars.

 

The solenoid is very easy to replace once you drop the pan. Disconnect the wire from the plug on the trans case and remove one bolt and the solenoid comes off. I assume this trans that you added is NOT a switch pitch. The switch pitch transmissions use a second identical solenoid for the converter stator pitch control. Regular TH400s only use the one solenoid.

 

I once had one doing the same thing. When I pulled the trans pan found the wire inside the trans at the kick down connection was not connected. Plugged it back in and it worked great.

 

The Switch Pitch is also activated at WOT so it will show continuity also. Does the trans have a two prong plug or a one prong? The bottom one should be the downshift on a two prong.

I have a picture of the throttle assembly. Terminal 2 is the downshift connection

 

Trip is correct, you may be reading SP signal to the trans. Also as mentioned above, you can hear a click when activated.

 

Thanks, Joe. I think I will unplug the kickdown switch and leave it unplugged. I don't plan to be floor-boarding the accelerator on a 44 year old car any time soon. If I need to downshift, I can take my right hand and move the gear shift lever from D to S whenever I feel the urge.