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My torque convertor NEVER locks, PICS Page 2

badmix

badmix

1/2 ton status
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I think it locked once in the 8 years ive owned it. I had a drop in RPMs.

What would cause it not to lock?

1984 K5 w/ headers and holley carb and mallory dizzy .rest is stock

700r tranny, stock

4:10 gears with locker in back

33" tires
 
What happens to rpm when you cruise in 4th gear and lightly tap the brake pedal, without actually applying brakes?
 
that '84 should have a vacuum controlled little doo-hickey on the firewall that controls the lock-up on it.
 
yes I have a tach, seen it go from 2k rpm to 1800 once.

wasnt aware I need to install anything

Ive never hit the brake like described to check for TC lockup.
 
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I thought lock up was controlled by the computer. The computer gets it's input from the TPS on the carb. There are two pairs of wires going to the trans. If I remember right, they all come from the computer harness. One controls lock up and the other tells the computer when the trans is in 4th. This is how my 85 is.
 
badmix said:
Ive never hit the brake like described to check for TC lockup.
Click to expand...

Tapping the brake should cause the converter to unlock, and I find the resulting little increase in rpm easier to notice...

K85 Octane said:
I thought lock up was controlled by the computer. The computer gets it's input from the TPS on the carb. There are two pairs of wires going to the trans. If I remember right, they all come from the computer harness. One controls lock up and the other tells the computer when the trans is in 4th. This is how my 85 is.
Click to expand...

Not all 85's had the carb with a TPS, and I doubt an '84 came with that...
 
K85 Octane said:
I thought lock up was controlled by the computer. The computer gets it's input from the TPS on the carb. There are two pairs of wires going to the trans. If I remember right, they all come from the computer harness. One controls lock up and the other tells the computer when the trans is in 4th. This is how my 85 is.
Click to expand...


This is what my comment is based on.
 
Right b4 I got rained out, I briefly looked under the hood. On pass. side right next to the A/C evap box, there is a thingy on the firewall with a vacuum hose going in and elec wires coming out. Is this part of the TC Lock Up?

What all can I check for and/or replace? I keep reading how ill destroy my tranny if it never locks up going down the freeway. :confused: .

I know my TV cable is adjusted properly, Ill re-check it once this monsoon goes away.

I never got a chance to climb under the truck. Is it possible this switch on the fireway went bad? Easy to get a new one?

Thanks. :D
 
badmix said:
...I keep reading how I'll destroy my tranny if it never locks up going down the freeway...
Click to expand...

Shouldn't this have happened already - it's 8 years, after all?
 
jms said:
Shouldn't this have happened already - it's 8 years, after all?
Click to expand...

Yes in theory but its a heat thing. If you only drive an hour with a lock up converter not locking up and then the truck cools down nothing will happen. Jump on the freeway for 2-3 hours and you'll burn that bitch right up.
 
I dont drive the truck much but I have been doing 2 hour one way interstate ones once a month for a year now. So, its 2hours one way and then 2hours back later on in the weekend.

Like I said, ive only seen the RPMs drop 2-3 RPMs once, infact I think I made a post about it when it happened a year or so ago. lol.
 
I was just under my truck reinstalling my headers. There are two sets of wires hanging down. One is a 4 pin and one is 2 pin. Im guessing these went to either the old Quadrajet carb or the old Distributor. WOuld these have anything to do with Torque converter lock up.


Also. I seen the under the dash a white plunger type thing at the top of the brake peddle bracket. From my readings this has to do with the Brake light switch AND the TC lockup. Now it this is threaded, is it possible that it could be too close to the peddle plate and always putting a lil bit of pressure on that plunger thus keeping TC from locking up?
 
The 4 pin might be for the plug in on the trans just above the pan on the drivers side. Is the 4 pin shaped like a square with a "clip" on it?
 
yes, check your plunger on the brake pedal. Mine had two plungers actually, white one and black one.
 
well, one would be for the brake light switch, the other releases the torque convertor from lock-up,

it's suppose to lock up with that little vacuum switch under the hood when it senses a certain level of engine vacuum/rpm.

when you hit the brake, the switch under the dash overrides and releases the TC.

but if the little 4-prong plug on the drivers side of the trans is not plugged it, it'll never work,,, obviously
 
There is no computer control except for California trucks. But even then, I don't think the CCC computer controlled lockup. I thought that came with TBI. I've never seen a CCC truck, but I wouldn't be surprised if the lockup controls were exactly like the other carb trucks. Do you have a little vacuum switch near the brake booster?

Since the transmission hasn't burned up yet, my guess is that lockup is working. There are two brake switches - one for the brake lights and another for the lockup. Probably that switch is never breaking the circuit. So as soon as the tranny goes into 4th it locks up and doesn't unlock until it downshifts. Or somebody bypassed the brake switch? You could measure the voltages on the transmission connector.
 
I seen the two plungers under the dash. One has alot of wires and connections and one just has two wires , blue and brown I believe. Nothing looks tampered with.

I just drove truck, its either always locked or it never locks up, I tried the taping of the brakes while driving on freeway, nothing happened, no drop in RPMs.

I have a vaccum switch on passenger side of truck, right beside the A/C box on the firewall. Vacuum line goes in and the otherside has a couple wires that go thru the firewall.

Ive got a Trans temp gauge, its plugged into the drivers side of the tranny where there was an empty plug. My gauge reads 180*. so dont know that is good or not.

So I still not sure what to check for or test?

What do those plugs that are unplugged do? Both are FLAT plugs, one is 4 prong and the other 2 prong.
 
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Ok. poked around the truck some. The tranny switch is connected.

I did find that I have 2 vacuum switches. I have no idea where each of them go BUT I after moving some wires out of the way, I did find that the vacuum line going to the drivers side switch was missing. I just "T" into one of my other vacuum lines to this switch, I havent driven it yet, will do so tomorrow.

Drivers side.

driver.jpg


Pass. side.

pass.jpg
 
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