??? Try to hang in there with me. I've posted on the help forum about the TPS location and have previously searched the forums. I have a '96, 2500, 4x4, 8880#, 4:11 rear, auto transmission. The Problem.. When starting the truck and heading out, the od unit will not work-most of the time. While going down the road, I shift into neutral, turn the key off-then back on and then it will shift into od. [Note: I installed the NAPA choke cable fix for the faulty fuel solenoid, thanks to the help I got here. So turning the key off is not interupting fuel flow.] I've replaced the auto trans icecube relay in the the relay panel, I think that this helped-but it did not totally fix it. Occasionally while going slow in traffic the same problem happens, try to accelerate and it will not go into od, even though it has been working. Looking at other post's, the TPS could be the problem-BUT- would the TPS cause the od lockout not to work? When all is working as designed, the od lockout will work (lite comes on) but lock out (and lite) will not work when the problem is present. I believe that it is an electrical problem. Are there any other relays, that are accessable, in this circuit loop. I've got a long road trip in front of me and I'd like to get this fixed (without the help of my friendly dealer) before I head out. Thanks in advance, all input is welcome. <br>warden

 

Warden are you the one in the same warden from ford diesel.com. The tps Is on the outside of the injection pump right near were the throttle cable hooks on. Look on the tech facs and ther is instruction on how to check it. It can do funny things with overdrive. Matt

 

I know there are many things that affect OD lockup and shift. one is engine temp on a cold truck they either will not OD or lockup so the engine keeps rpm's up for faster warm up. So check ur temp sensor. TPS also control tranyy function as far as shift points go and line presure, but a bad tps may also give u a hesitation cause it works with the injection depending on vehicle year. The speed distance sensor will also keep ur OD from coming in ot sure about lock up. To check ur converter lock up drive down the road and tap ur brake pedal if the rpm's jump up alittle then ur lock up is working. When u loose od try ur cruise control if that doesnt work when OD is not working loose at the VSS. The VSS may also affect ABS. Its alot of stuff but unfortunately evrthing is tied together. U may also want to check the voltage and grounds. Especially on the low temp tranny realy u replaced it could be a low voltage not pulling the realy in. Good luck<br>Dan

 

Hey Matt, Not the same warden from the Ford forum. Thank you both for the feed back and keep the replies coming. I learn from each one. Thanks, warden

 

Warden<br>I was having some symptoms VERY similar to yours and figured out that MY problem was self induced. At one time I was going to hook up a &quot;mystery switch&quot; but for reasons I won't say here I never did complete the job. The wire that was tapped into the pcm wire eventually worked its way down to where it was touching the painted inner fender. I would have to shut the key off to get O/D to work, then do it again to get O/D off. I found it kinda by mistake when I was adjusting my tps. I don't know if you are the original owner or if you have a lock-up switch, but, it sure sounds like the same thing. Look behind your air box and you will see the plug for the pcm. to see if MAYBE there is any wires that might be rubbing and worn through to the point of shorting. Seems to me that there is a seam just under the plug for the pcm (too dang cold for me to look) that might be the culprit. If you can't find anything try going to DTT's website: www.dieseltrans.com and you can either post a message for Bill K. or get the phone number and call him. He will do his best to try to talk you through it. I know. He tried his darndest to help me.<br>Tom