I've got a '99 Ram with a 5.9, 46RE trans. A couple of months ago at a speed range of between 55-60 mph in overdrive, the torque converter began to unlock and lock intermittently. It results in a blip of about 300 rpms for a couple of seconds and then locks again. I've changed trans fluid with ATF+4 and checked level in neutral. I've had the codes read and was told that the only code was for a bad O2 sensor. The truck has 125,000 miles on it and has been pretty much flawless up to this point. Are the two things related?

 

Probably not. TCC problem is probably throttle position sensor. Did you replace to O2 sensor? It's prolly past its useful life span.

 

I'll probably replace both TPS and O2 sensor just to be safe. Thanks for the help.

 

I replaced my tps and fixed mine

 

I replaced the TPS this weekend. The first time I started the engine after replacing, it revved to 2000 rpm and then slowly came down to 1000 after a minute or so. I took it for a drive and everything seemed to be fine. The torque converter problem was intermittent before, so I'm not sure if it "fixed" that problem yet. As soon as I got home and put it in park, it went back up to 1000-1100 RPM and that's where it seems to stay.

 

I hope you disconnected the battery before changing the TPS if not go ahead and do it and reset the PCM. Otherwise you may/will end up with similar throttle issues again.

 

That did the trick. Thanks for all of the help.

 

Just wanted to post what finally cured the problem I had with my torque converter locking and unlocking in drive and overdrive between 45-60 mph...

Based on advice from this forum, I replaced both the throttle position sensor and the transmission speed sensor. Unfortunately, neither helped. After taking the truck to Sam Leman Dodge in Peoria, IL, I was pleased that the great guys there were able (and honest enough) to tell me that the problem was a $17 brake light switch. Total bill after 2 days of diagnosis: $170. I'll take that and run!

 

How in the world was it a brake light switch?

 

Glad you got it firgured out. If that stupid little switch goes bad it will def do it. It's the same switch that cancels cruise control and unlock torque converter if you tap the brake pedal.