torque converter keeps locking and unlocking at hiway speeds(65-75) need some sugestions on what would cause this to happen

 

There are a couple areas to check. I would probable check the Throttle Position Sensor first, then the Throttle Valve Cable.

The throttle position sensor on this year is responsible for determining throttle linkage angle, and creating the impedance necessary for the PCM to signal the torque converter solenoid to lock or unlock. The other item to check is the torque converter lockup solenoid, it is in the transmission and can lose connectivity - but check this last.

If the TPS is functioning properly, check the adjustment and condition of your Throttle Valve Cable that runs between the transmission and the injection pump throttle linkage. Generally you will find one end or the other cracked where it connects the inner cable to the linkage arm or bellcrank, or a bayonet clip on the outside housing on either end that has worked loose.

If neither the TPS or Throttle Valve Cable are the culprit, then look to the lockup solenoid and the wiring that connects to that.

 

One more thing to check for is brake switch adjustment... mine was set on a hair trigger and whenever I hit a bump, on came the brake light and the torque converter came unlocked.

 

Brake switch would be my fist check. You don`t drive two footed do you...
You know one on the gas and one on the brake.
If you active the brake switch while driving it kicks O/D lockup out.

 

what about line pressure in the trans?

 

thanks guys, don't know about line pressure but now i have somewhere to start with, I'll check it out and when i fix the problem i will let yall know what it was.

 

I know this is elementary , but make sure you're not low on trans fluid .

 

I don't think the ATF level would affect the electric lockup solenoid from functioning correctly.

 

I could be wrong , but it seemed to me it did on my 47RH

 

Low ATF level could certainly feel like the converter isn't locking, I was just pointing out that it shouldn't affect it electrically.

 

The TPS on my truck did the same thing. Shifted out of gear at hwy speeds. NAPA has the part and it takes about 5 minutes to replace it. There are all kinds of remedies, spraying the linkage with contact cleaner, adding a potentiometer, etc. The quickest and simplest is to replace the thing. They aren't cheap. About $180 at NAPA, $220 at dealer.

J

 

I'm having the same problem. I checked and cleaned everything replaced the tps, new brake switch, and today a new lockup soleniod. sometimes it works for the first 5 miles in the morning then it's done for the rest of the day. any ideas?

 

Clean all grounds (both batteries and the ecm). Make sure the wires running over the alternator are not rubbing on it.

I did that and eliminated this problem on my truck.

 

adjust ur brake pedal switch first...it costs nothing and takes 3 seconds....after that the number one reason for what u desrcibe is a bad tps sensor...they're not cheap so clean all ur connections...check for exposed wires and cables that may touch metal...and check that brake switch

 

First i fixed my TPS which was loose, and that reduced the incidence of the unlocking, THEN I found out the pedal switch was jaked. cost about 20, installed. 5 minutes.