Hi. Sometimes when I am going along my truck all of the sudden downshifts and then up shifts and does that over and over again. Is it something bad or easy fix?

 

I assume you are having this problem with your 1997 F350? What engine and transmission does it have?

Is the Check Engine Light on or the O/D button on the shifter (assuming you have an E4OD transmission) blinking?

 

I have 7.5 and I don't know what transmission it has. It's an automatic. And the check engine light is on but it's on before it happens

 

The computer is trying to tell you something.. .pull the codes.

 

It's not on all the time. It was on way before this happened? Where's the computer on the truck?

 

and a close-up:

courtesy of subford

Your truck could be using an OBD-II computer system or a OBD-I. If it is the former you will need a code reader. If it is the latter you can warm up the truck then do this: Fuel Injection Technical Library » How To Run a Self-Test

Check the emission label under the hood to see which version you have.

If you have an OD button on the end of the shifter then you have an E4OD transmission which is 100% electronic controlled. Any engine or transmission sensor malfunction can make the transmission shift abnormally.

 

Mine doesn't have one in the cab. It's supposed to.

 

Yours does not have what in the cab? Computer (PCM)? Or a diagnostic port?

If there is no diagnostic port in the cab then your truck is running the older OBD-I style computer system. Which has the diagnostic port under hood near the driver side hinge.

 

Ok so it's under the hood. And it's a electrical problem?

 

More than likely it is an electrical problem, but finding the root cause is the key here. More than once someone on this forum has had their E4OD replaced or rebuilt to find out the problem is still there. The only way to know for sure is to check for codes starting with the Key On Engine Off (KOEO) tests and Continuous Memory (CM) display.

Unless you want to start throwing away money I HIGHLY suggest you start by running the KOEO tests and CM display. Once any issues are found/resolve there then you can move onto the Key On Engine Running (KOER) tests.

 

how would you do those tests?

 

Fuel Injection Technical Library » How To Run a Self-Test

 

This or the same link I posted in Post# 6.....

 

Yep, I knew you had already posted the link, but since he seemed to miss it, and proceeded to ask again, I thought I would throw it out again....

 

At what speeds and what gears does it do this? Mine will do it in traffic at certain speeds (right when youre hovering around the point it wants to shift into 4th/OD) It will flip between 3/4 everytime you so much as touch the gas/ let off the gas.

I find in those odd conditions, just hit the OD OFF button, and I'm golden, when I get to a spped that it is comfortably able to stay in OD I turn it back on.

But if its doing it all the time, then yeah, run the codes and figure out whats up...