tcc help needed !

[1quickfrc]

last fall at the dragstrip my transmission started doing a "stacked shift" if thats what you call it. At about 20mph or so it goes right through the gears and goes into lockup. I just replaced the tcc solenoid last week and it still goes into lockup at about 20mph. I unplugged the transmissions four prong plug and it shifts like it is supposed to now. I also checked my tv cable and plunger when I had the pan off none of that seemed to be faulty.

Since it is a new tcc solenoid what do I check now?
Bad/old wiring my problem or a junk tcc solenoid from advance auto the problem?

any ideas and tests that I can run would be appreciated thanks!

 

[Alky V6]

The fact that when you unplug the connector, the TCC is no longer engaging tells me you have an electrical problem.
The first thing to do is make sure the the ground circuit in the transmission is not grounding in the pan somewhere. If the new soleniod came with a complete internal harness, then I doubt that is the problem.
If that checks out OK, then the next thing to do is to check the grounding circuit external of the transmission.
The 'A' terminal on the trans connector should be hot all the time with the key on. The only exception would be if the brake pedal is depressed.
The 'D' terminal circuit is the grounding circuit for the TCC solenoid. It is the circuit that is commanded by the ECU to engage L/U. This is where I think your problem is going to be. When the computer is not commanding L/U, you should see 12V on this circuit. When the computer grounds this circuit to cause L/U, you should be low, or 0 volts.
If the 'D' circuit is low all the time, there is either a fault with the computer, or the 'D' circuit is shorted to ground.

 

[standupjskiguy]

tcc help

How does it shift when cold? If it shifts OK when cold you have another defective TCC.
What happens is they don't build enough clearance inside the coil core. The plastic is under pressure from the wire wound around the core. As it ages, it collapses onto the metal rod. When the trans heats up the plastic expands against the coil of wire and closes down on the rod holding it against the ball and keeping the passage closed. When the trans cools, the plastic shrinks and the rod releases.
I took my TCC apart and drilled out the plastic core just a bit, maybe .010 or so and I have since had no problem on my 85 and 87. The TCC is spot welded together but you can break those welds and you can either re-weld or just install carefully, the mounting screws will hold it together. If you have the shifting problem cold or hot, then yes you have an electrical problem.
I hope this helps.

 

[1quickfrc]

Ok thanks a bunch guys! hopefully tomorrow I can get some time to get things checked out and see if I can narrow it down and find the problem!

 

[1quickfrc]

ok so the car has been in storage for three years now and I finally got it out to check the tcc problem.

location A on the trans plug is 12v with the key on and when the brake is depressed it drops to zero so that's good.

location D is zero at all times.

looking further into the tan/black wire (location D) I found that on the aldl connector pin F had a suitcase clip on it going to a fan override switch. with the fan switch in one position it sends a ground signal to pin F. I'm no wiring guru but if that fan switch grounded out pin F when the computer was sending 12v to pin F wouldn't it short out the computer?

I'm assuming the previous owner was looking for 12v for the fan switch and saw with the key on pin F on the aldl had power and jumped it there. So as far as I can tell I need a new ecm unless I want to hook up a manual tcc switch.... which I would rather not.

 

[mikestertwo]

The computer doesn't send 12V to pin "F". Pin "F" gets the 12V through the lockup solenoid which comes though the brake switch. The computer grounds pin "F" to enable the lockup solenoid. If someone where to put 12V directly on pin "F" when the computer commanded lockup it will blow the driver in the computer.

 

[Alky V6]

The D terminal will show 12V when the computer is not grounding (commanding) lockup.
When the computer does command lockup and grounds D terminal, the voltage reading will drop to 0 since D terminal is the ground side of the load (the lockup solenoid). If someone spliced into that circuit to pickup 12Vs, well that isn't the circuit to be doing that.

 

[v6turbo87]

Grounding pin F of the ALDL will cause lock up as soon as the tranny shifts in to 2nd gear. It sounds like someone wired in a TCC LOCK UP switch not a fan override switch. What makes you think it is a fan override switch???

Posted from the TurboBuick.Com mobile app

 

[v6turbo87]

BTW to get the high speed fan to come on a ground signal is used also. Maybe somebody wired A double throw switch in with the common attached to ground. Flip it one way you get to convert a lockout in 2nd gear. Flip it the other way you get the high speed fan to come on. Back in the day this was a common set up for racing. Flip it to lock up to race then flip it the other way to cool it down the staging lanes.

Posted from the TurboBuick.Com mobile app

 

[1quickfrc]

I know its a fan override switch because when you flip the switch the fans come on....... It was on there when i bought the car and was told it was for the fans. I used it in the pits to cool the car down and it worked pretty good. after looking at the switch i would guess they used it to both control the fans and the lockup but i had no idea it was hooked into the tcc wire until just recently. i unhooked that jumper wire from the aldl and it shifts great now so a big thanks to everyone who contributed to this thread!