Hey guys. Today after leaving the convenience store my transmission started acting funny. It doesn't want to shift out of first gear, I have to get the rpms over 2500 and basically leave it their for a while before it will finally shift. Once out of first it seems like it shifts fine. While in first gear I also notice some noise comming from underneath, almost like a pinging sound. Once out of first it goes away. My Excursion is a 2001 7.3 with 198k miles. 4" exhaust, and Predator Diablo tuner always set to 60hp economy. I reset the pcm back to stock to see if that would make a difference and it did not. I checked the fluid when I got home and it was normal. Please tell me my tranni isnt toast.

 

Might want to check your Output Speed Sensor on the back of the tranny?

 

Why the output speed sensor? I can't see how that could cause this problem. Why would the sensor only cause a 1-2 shift problem? If it were bad how does it fix itself after the 1-2?

The problem is a failed mechanical diode. That's a type of one way clutch inside the transmission. Unfortunately it means it is rebuild time.

 

I have an 01 myself and I have been waiting to see the same thing. If mine lasts till 198k I will be excited. There are plenty of guys around here that can point you in the right direction for a new one

 

So how many of these ticking time bombs are there out there?

Perry

 

Help me understand. If the problem is persistent in shifting in other gears and not just from 1-2, then this sensor could be the culprit? Thanks.

 

Unfortunately I'm thinking you are correct. I found other threads where people were having the exact same issues I'm having and it turned out to be the diode letting go. Apparently this is a common issue with these. I called my local transmission guy and gave him a description of whats going on and he told me the same thing about the diode. Looks like I'm rebuilding.

 

All the diesels from the start of 2001 production through March, 2001. I don't know the number that were built.

 

I have a 97 F150 5.4L AOD trans with the same 1-2 shift issue. It will shift to second if I let off accelerator a little. Is this also the internal diode or something else.

 

No, the F150 didn't have that problem. It's something else.

 

Thanks for the reply Mark, it acts like the throttle pressure rod is too short if it had one. Do you know what replaced that?

 

The computer replaced that. You need someone to do a computer/transmission diagnostic.

 

Curious what the fluid looks like and smells like?

 

Fluid looks and smells good.