Torque converter lock up / break switch?
Thread Starter
Racer
Joined: Nov 2013
Posts: 338
Likes: 8
From: South NewJersey
Torque converter lock up / break switch?
I've been having this problem since having my new trans installed , I thought they gave me the wrong torque converter. my car felt almost like it was starting in second gear. by the way I have a brand new moderately high HP carbureted engine. I asked the shop who built my trans if the lock up properly working since it was not activated by the computer anymore and they said yes they "checked it" so I thought the T/C must be too low of a rpm my engine builder suggested a 2800rpm T/C so I thought it must be a stock one the trans shop gave me and that's why the car feels like its not accelerating the way I thought it should.
Anyway today I do some break work and while Im under the dash I realize one of the two switches activated by the break pedal was not touching the break arm so I moved it so it was. When I took the car out to test the breaks my T/C problem is fixed and my car feels like its a beast. Was my T/C locked up the whole time (about 300 miles) could that have hurt something? I always thought a 700r4 could not be locked up in first gear, can it? I know this is long winded but I have been dealing with this for months.
Anyway today I do some break work and while Im under the dash I realize one of the two switches activated by the break pedal was not touching the break arm so I moved it so it was. When I took the car out to test the breaks my T/C problem is fixed and my car feels like its a beast. Was my T/C locked up the whole time (about 300 miles) could that have hurt something? I always thought a 700r4 could not be locked up in first gear, can it? I know this is long winded but I have been dealing with this for months.
Race Director
Joined: Apr 2002
Posts: 10,036
Likes: 346
From: Anaheim CA
I don't know what your setup is, but normally the ECM locks the torque converter. My car is stock and the torque converter will lock in all gears, including 1st. The lockup speed is set to 40 MPH in my ECM (stock) and it does lock at that speed. It doesn't matter what gear the trans is in.
Thread Starter
Racer
Joined: Nov 2013
Posts: 338
Likes: 8
From: South NewJersey
Is there a way to find out if the converter is locking up now ? I know I can purchase a switch from Summit or Jeggs . I have also read on here I can make one. I thought I had this issue taken care of by asking the shop who built and installed the trans..Guess not... hope the TV cable is right ? I left that to them also 
Melting Slicks
Joined: May 2014
Posts: 2,891
Likes: 591
From: New Port Richey FL
now if the switch was not making contact with brake pedal and the switch functions correctly it would treat it like the pedal was depressed and not allow the the lock up, so I suspect you have a intermittent working switch and someone pulled it away to free up the converter.
Safety Car
Joined: Aug 2009
Posts: 3,751
Likes: 275
From: Melbourne, Victoria, Australia
If your torque converter does not lock up you will notice the rpm a lot higher when going uphill, below is a pic from my shop manual (85)
The 84 should be similar. A faulty tcc switch will hold out the lock up, see the pic of what happened to my tcc switch.
Note the plug on the drivers side of trans may not be fully plugged in,
however that happened to me and only affected rpm.
Check your TV cable is adjusted correctly, that tells your trans what pressure to run. smooth early shifts at low rpm and firmer high rpm shifts at full throttle.
Thread Starter
Racer
Joined: Nov 2013
Posts: 338
Likes: 8
From: South NewJersey
I am pretty sure my T/V cable is correct , shifts feel firm on acceleration and if I open the throttle by hand the cable is really tight. Is there any way to check if that has been done properly?
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From: Freedom is never more than one generation away from extinction.
St. Jude '03 thru '24
The TC clutch is all steel. Low pressure will cause it to overheat thus burnt paint on the outside of the TC.
The thing that could be damaged is the clutches. Only time will tell.
I use a manual switch to control the TC connected via the ODB port.
Works great. No need for special switches and other stuff.
The thing that could be damaged is the clutches. Only time will tell.
I use a manual switch to control the TC connected via the ODB port.
Works great. No need for special switches and other stuff.
Safety Car
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From: Long Island, NY
Le Mans Master
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From: Australia
Race Director
Joined: Apr 2002
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From: Anaheim CA
You can tell if the torque converter is locked or not by connecting a test light from ALDL terminal F to terminal A. Note that the voltage is "backwards" and the light will be ON when the TCC is NOT locked and will go out when the ECC locks.
Instructor
Joined: Aug 2014
Posts: 144
Likes: 2
From: Ca
So when you step on the brake peddle shouldn't the light stay on? And if the light goes out when stepping on peddle could that mean bad solenoid? When I turn key on light on! Put foot on brake light out ! In drive light on! But when I get to 3/4 light stays off but TCC drops out engine idles and car coast or bring rpms up stall rpms car drives great while driving if I lightly push brake peddle tcc unlocks rpms come up let off peddle locks car drives fine! But don't like the coasting every time I come to a stop! Any ideas? Thanks for any input
Race Director
Joined: Apr 2002
Posts: 10,036
Likes: 346
From: Anaheim CA
So when you step on the brake peddle shouldn't the light stay on? And if the light goes out when stepping on peddle could that mean bad solenoid? When I turn key on light on! Put foot on brake light out ! In drive light on! But when I get to 3/4 light stays off but TCC drops out engine idles and car coast or bring rpms up stall rpms car drives great while driving if I lightly push brake peddle tcc unlocks rpms come up let off peddle locks car drives fine! But don't like the coasting every time I come to a stop! Any ideas? Thanks for any input