My converter is unlocking, then locking back up, then unlock again (and again, and again) when I am at highway speed ( 50mph/60mph) and light load.

I've been serching similar issues but all I found was a ground problem on 2 gens 24 valves with 47RE, I believe I have a 47RH.

Is it same problem ?

 

Try using the search function and look for TPS (throttle position sensor). I think you will find tons of information to read. This is a VERY common issue. You can clean it or replace it.

 

Lots of things can cause this but the 2 most common are the tps (discussed already) and the little switch that causes your brakelights to go on when you hit the brakes. They wear out and activate the brakelight circuit, and kick it out of lockup.

Next time it kicks out of lockup, put your toes under the brake pedal and pull it up a little. If it locks up again, and you can control the lockup that way, there's your problem.

 

Excellent hints, thank you guys. I will follow them.

 

Let us know how you make out. The brake switch is about 10 or 20 bucks.

 

Start here> TPS Testing and Adjustment

 

TPS.. mine was the same way...I modded the TPS and now locked in 4th on the highway... I can get into the go pedal and roll on at 50 and she'll pull hard up till 75mph without disengageing. Huge improvement!

 

It is not the brake switch, I will try to adjust the TPS a little, if nothing change I will follow complete instructions by the weekend.

 

Stock gov springs or no?

 

Everything stock on this truck.

 

I gen no voltage from purple wire. I assume TPS is shot. They are $ 270 at NAPA

$ 175 at Autozone

Any place cheaper ?

 

Better news, I fixed the broken TPS.

I removed it and turned the rotating part several times (many dozens of times), putting a little pressure inward and outward. Since this is a rheostat based unit, it works just like the volume dial of a radio. Do you remember when every time you turn volume up it was scratchy ? Well to fix it you had to turn up/down many times, it would clean the contacts and eliminate any scratching noise.
Same concept here.

Now my transmission is like brand new, shifts fine, locks and unlocks with no problem, and I saved 200 bucks from buying a new one.

I will study how to open it without breaking it and clean contacts better.