Replacing TPS on my F-350 - Diesel Forum

F350 · 11-01-2009, 12:30 PM

I'm being told that the TPS is causing the shifting in and out of OD in my 350,
I'm out of work, need my truck and can't really afford a dealer or mechanic right now! Where is it located and how hard is it to replace? Any tricks or reprogramming needed, or is it just a unplug and replace?? Thanks!

**bugman** · 11-01-2009, 12:52 PM

First off who was it that told you that it was the TPS? Also what are the symptems or what are you doing when it shifts out of OD or could it be the torque converter unlocking?

F350 · 11-01-2009, 06:03 PM

Just had complete tranny re-build, was having problems with the converter "locking up" when I shifted into reverse and then it would stall the engine,or take off while you scrambled to get it out of gear or shut down. Had also had trouble before and after rebuild with cruising about 60-65 on expressway and it would drop out and back in to OD. Using shop I trust for the trans repair, he was the first to suggest the TPS might be the overdrive problem before we ever got into the repair, but the locking problem was getting unsafe so I went ahead and had him replace the TC with a new, not re-man billet TC. While he had it out, I told him it was getting some age on it, so go ahead gut it and upgrade as much as possible. Truck is 15 years old, 145,000 miles, had done some reading this weekend and it seems 60+ is the normal life for these switches? Saw lots of the same symptoms listed here and other sites for the TPS. I know I 'm doing some guessing, but was trying to weed out some of the simple(and cheap) things first to keep from spending money I can avoid.
Am I heading in the wrong direction?

Now that you ask it, how can I tell the difference in the converter unlocking and it coming out of OD. When it happens tach jumps about 600 rpms, I just assumed (yea I know) it was coming out of OD

**bugman** · 11-01-2009, 09:07 PM

The next time that you are on the road and running up to speed see if it drops out when you use your turn signal. If it does you may want to check your lights and the third brake light on top of the cab. I know it sounds funny that they would cause a problem but they do. Another member had the same problem in this THREAD and came up with a burnt out bulb. As far as telling if the torque converter is unlocking or if it is just droping out of over drive try this. After the event happens press the OD off button. If you get another shift, then the first one was the torque converter unlocking. If you don't, then the first one was a downshift from overdrive to third gear. If you still have problems you may want to PM Mark Kovalsky. He is the automatic tranny expert on here.

F350 · 11-01-2009, 09:35 PM

thanks, I'll check bulbs in the morning, and give the other suggestions a try on the road

red166 · 11-07-2009, 06:47 PM

I had the exact same problem on my 95 ,,,,, replaced the burnt bulb on the cab and the problem disappeared,,,, still have the new TPS in my glove box,,,,, still waiting for it to happen again ,,,,that was 10000 kms ago..

FYI

F350 · 11-16-2009, 10:56 PM

Bugman, dead on!!!!!! Sir I thank you, brake bulb in the back of the cab was trash. Less than a $1 fix!!!! I love it. Thanks for saving the day. Only Ford could have a brake bulb screw up an entire truck.