torque converter lockup not working

[guitarfreak235]

Hello all, I've had trouble with torque converter lockup for some time now. I've gotten it to work again in the past, but never seemed to be functioning right. When it locked up, it wouldn't unlock unless I got the trans to downshift. In 4th gear it would be locked no matter what, and the engine would kinda lug under higher load.

Anyways, it stopped working and now I can't get it to work no matter what I've tried. I replaced the vaccum switch for lockup with an adjustable aftermarket relay, and no matter what setting I have tried (normally open or normally closed, high vaccum or low) I can't get it to work. I checked my haynes manual and it offers no help.

Im at a loss now, and would love to get lockup working. Does anyone have any info on how this system works, and how to diagnose issues? I believe I've asked this a long time ago, but can't seem to find any old threads I started


...should I try connecting the 2 wires to see if lockup occurs? any info is appreciated

 

[crpntr78]

I'm assuming this is on a 700r4. Connect the two wires and test with a test light. If no power, probably the solenoid has failed and will have to the pan to replace. One other thing to check is the power connection in the fuse block., that's assuming it's still the factory set up.

 

[74 Shortbed]

Also check the switches on the valve body..

 

[guitarfreak235]

I'm assuming this is on a 700r4. Connect the two wires and test with a test light. If no power, probably the solenoid has failed and will have to the pan to replace. One other thing to check is the power connection in the fuse block., that's assuming it's still the factory set up.

Ah yes forgot to specify, but yes its a 700r4. So the wires will always be hot when the ignition is on?

Also which fuse would that be? I checked the fuses and none of them seemed to make sense by name, I figured it might not be fused..

 

[guitarfreak235]

Also check the switches on the valve body..

I don't think I was aware of these

 

[74 Shortbed]

I don't think I was aware of these

Here ya go.

You must be registered for see images attach

 

[guitarfreak235]

Here ya go.

You must be registered for see images attach

oh right on the inside of the transmission. Yea i was hoping to check all external possibilities first before I go tearing apart my tranny.

is the vacuum switch the only external component that might be faulty?

Also, this tranny is the stock one in my 86. It was the year that the carb had electric choke and the computer could retard the ignition timing. is there a posibility that the tcc function was somehow electronically controlled too? I read how they were on f bodies, but not sure about my setup. If so, Id like it to only be vacuum controlled. (I've disconnected the ecm completely, I have no emissions controls or anything anymore, running a 73 350) I could live with a manual switch, but if i did that I'd want to have off,auto,and on options. I've seen a couple diagrams where people have set it up that way

 

[74 Shortbed]

oh right on the inside of the transmission. Yea i was hoping to check all external possibilities first before I go tearing apart my tranny.

is the vacuum switch the only external component that might be faulty?

Also, this tranny is the stock one in my 86. It was the year that the carb had electric choke and the computer could retard the ignition timing. is there a posibility that the tcc function was somehow electronically controlled too? I read how they were on f bodies, but not sure about my setup. If so, Id like it to only be vacuum controlled. (I've disconnected the ecm completely, I have no emissions controls or anything anymore, running a 73 350) I could live with a manual switch, but if i did that I'd want to have off,auto,and on options. I've seen a couple diagrams where people have set it up that way

Vacuum switch and all your connections, don't know how the computer thing works but if all that stuff is disconnected you still need a complete circuit. you don't need to take the tranny apart just drop the pan and it's all there, you don't need to go any further.

 

[guitarfreak235]

Vacuum switch and all your connections, don't know how the computer thing works but if all that stuff is disconnected you still need a complete circuit. you don't need to take the tranny apart just drop the pan and it's all there, you don't need to go any further.

OK. do you know what fuse the system might be using? also, should directly conecting the leads at the vacuum switch reveal if the problem lies in the transmission? (neglecting the fuse and connections themselves as sources of the problem)

maybe Im overthinking it, but I've been a bit confused about this for a while. I'll double check everything externally, but im beginning to think the problem might be internal..

 

[74 Shortbed]

OK. do you know what fuse the system might be using? also, should directly conecting the leads at the vacuum switch reveal if the problem lies in the transmission? (neglecting the fuse and connections themselves as sources of the problem)

maybe Im overthinking it, but I've been a bit confused about this for a while. I'll double check everything externally, but im beginning to think the problem might be internal..

Sorry that I wouldn't know but you should be able to trace it, if you're vacuum switch is working and activated you should have power at the plug on the case, if not then you would have to trace it to the source, if you have power then it would be time to drop the pan.

 

[guitarfreak235]

Sorry that I wouldn't know but you should be able to trace it, if you're vacuum switch is working and activated you should have power at the plug on the case, if not then you would have to trace it to the source, if you have power then it would be time to drop the pan.

ok, thanks for the help!

 

[crpntr78]

It's not actually fused. Should be a single wire plugged into a port near the top of the fuse block. They are colored up there but can't remember which color. Brown? or Orange. Also don't forget the TCC lock up control goes through the brake switch as wel.

 

[Boone83K10]

Do you have cruise? The 700r4 lockup is hooked to the cruise vacuum switch located on the brake pedal. The black one is for brake and the white is cruise/lockup. Mine wouldn't fully close so no lockup. Take it off and take it apart, clean it up and bend the taps slightly. Mine has worked fine ever since.

 

[guitarfreak235]

It's not actually fused. Should be a single wire plugged into a port near the top of the fuse block. They are colored up there but can't remember which color. Brown? or Orange. Also don't forget the TCC lock up control goes through the brake switch as wel.

Yea, this is the sort of thing i was looking for. I believe ive heard that before but had forgotten...

Does anyone have a diagram of the whole system? not inside the trans but the external parts? is it just the brake switch and vacuum switch? ...or is there more? Heck I don't even need a diagram, just a run through on the external components so I can check those individually and diagnose the problem. In all the research I've done, I've yet to find any complete info on the external componentry

 

[guitarfreak235]

Do you have cruise? The 700r4 lockup is hooked to the cruise vacuum switch located on the brake pedal. The black one is for brake and the white is cruise/lockup. Mine wouldn't fully close so no lockup. Take it off and take it apart, clean it up and bend the taps slightly. Mine has worked fine ever since.

good to know! yes i have cruise. its not working now cuz i dont have all the vacuum hoses connected, but was fully functional before. If cruise control works, then this would not be the problem correct? All I need to do is put a hose to the vacuum reservior to test, the rest is still there. stupid hose split and just haven't spent the time to fix.