E4od acting up

ok so here we go od light flashes and it has hard shifts , has a brand new transmission less than a month old. Changed vss and abs light still on and shifting bad , what else could this be. ? It’s a 1993 F350 factory turbo

Fipl, but check for any bad brake lights first.

Scan it for codes.

I think whatever is tripping off your ABS system is at the root of your problem.

Trace through the VSS loop very carefully.

It feeds both ABS and the PSOM, which tells the transmission control module how fast you are going. Without that signal, your transmission is gonna behave really bad.

Trace that VSS circuit from the differential to the ABS module and PSOM. Given what has been said so far, I can't help but point you there. My failure was an intermittent issue in my PSOM, and it drove me nuts. Ended up toting around a battery powered oscilloscope hooked to the PSOM output circuit to nail that little sucker in the act.

If your ABS light consistently lights up at 36mph then look at your brake lights/wiring like Wes suggested. Also if you by chance converted to LEDs at your brake lights then the system won't pull enough current and that's why your ABS light would come on at 36mph.

I chased this for a while, and I hope writing about this doesn't jinx it, but currently it seems to be fixed. Definitely scan the codes if you have not done so. Mine was 29 which is insufficient VSS signal. I replaced the rear end sensor immediately with no effect. After a wild goose chase trying other things I tried swapping the NAPA sensor with a Ford one, and for a few weeks now no more flashing OD light.

Same code I was getting... But the transmission computer never sees raw VSS.

What threw me for so long is that my speedometer needle was steady. Which led me to believe I had clean VSS signal.

It wasn't until I scoped the VSS signal that the PSOM was giving the PCM that let the proverbial cat out of the bag.

My PSOM output signal was available at a connector that was intended for cruise control. Which made it much easier for me to tap into.

I found this helpful.

http://www.atraonline.com/gears/2007/2007-01/2007_01_04.pdf

I had decent VSS going to the PSOM, but the signal leaving my PSOM would intermittently drop out. When I bought the beast, it did this rarely. Maybe a few times a month. But it slowly got worse.

My speedometer needle was steady. Fooling me to look elsewhere. I finally got so desperate as to buy a battery powered oscilloscope and start tapping into the control signals. VSS to PCM was first, because that was what the error code was pointing to. Yup, next time the transmission went amuck, there was no VSS signal either.

Yet, the speedometer was still showing proper speed. Looked like I was getting good signal to the PSOM. But not getting anything out.

So, l got another off of EBay, did a swap, and I have not had another episode since.

One thing I will leave with you. I discovered I could usually induce the gremlin by rapping on the speedometer reset or select buttons. Not consistently, but the probability of my little gremlin was quite correlated to my doing this.

Incidentally, if you have an audio frequency generator, its easy to bench test to verify your new PSOM works. I used a 600 ohm 1:1 audio line transformer to isolate the VSS input so as to make the PSOM think its seeing a coil of wire in a magnetic field.

There is an android app on F-droid that turns an android phone into an audio signal generator. I did not test this way, but it looks like that oughta work... I would still use a transformer for isolation though. I am talking those little audio transformers that were so common a few decades ago.