Was driving my new to me 7.3 psd this morning and it hesitated on a downshift on highway, and OD light started flashing. Any ideas what this is before i spend the money to have codes pulled. 320k miles.paid 900$ for her. Got a heck of a deal.

 

 

There are about 50 different things that can cause the OD OFF light to flash. There are two ways to find out what's wrong.

First, you can get the codes read and that will tell you what the PCM saw that it didn't like. The second way is to change everything that could cause this and hope you find it. That would include several sensors, the whole transmission, the trans wiring harness, the computer, the rear axle, etc.

 

Were I you I would invest in a code reader (about 35$) rather than pay to have your codes read. I recently learned how to pull my own codes using the CEL and there is just some personal satisfaction in knowing that you did it yourself. Either way, getting the codes is the place to start. Good luck with your new truck!

 

Just throws the OD flash, no check engine. From my understanding places like autozone or badic scanners couldnt read that? Im thinking torque converter. If im getting into it to get on the highway or when its locked it seems to cause it. Happened when mashing it on the highway. Just drove 45 minutes from work to home easing into it and no OD light came on.

 

E4OD is controlled by the ECM, so any codes would be stored here. The check engine light only tells you about engine faults. The OD off light tells you there are transmission faults. Either way you have to check for codes to figure out what is wrong.

Go out and buy one of these, or one of the many like it.
Innova code scanner #3145

 

Pulled codes today, got a p1728

 

There is a good chance it is the torque converter.

Is the front face of the torque converter blued? It will get that way if the torque converter clutch is slipping, and that's the most common cause of a P1728 code.

 

Im going to pull my inspection cover later, but thats my guess too, cracked piston internal leak, because it just throws the code getting on it when locked. So it does make sense.

 

Always check your MLPS first with an E4OD.

Another quick test: Lockup should release if you tap the brake pedal. Try it pulling up a grade. Might have more than one brake switch.

Has the fluid ever been changed?

The flashing light is a code. There are flowcharts in manuals to troubleshoot the codes. Test after test in a specific order.

 

How did you get a 5-character code out of a 1993 computer?

I thought that vintage was 3-character numeric codes only?

 

out of a 1997 f250, havent added it to my account yet, bought another truck

 

Definitely torque converter. I can drive with OD off and cant slip it or get it to fault no matter how hard I drive.

 

That doesn't prove it's the torque converter. The code can only set when the trans is in fourth gear and the torque converter locked. No matter how much slip there is in third gear that code won't set.

 

your right its not definite, i did already order a converter, but with it only throwing one code. Its hard to diagnose​, and since you have to remove the TC anyway to pressure test it, so might as well sort of thing.