Ok, I'm new to owning a Ford, and new to a diesel this new. I've searched the forum and found somewhat similar issues, but not exactly my truck's issue. First the rundown: now owner of a 1995 OBS F-250 CCLB, 7.3L Powerstroke. Automatic trans 4wd. Someone came to look at the truck before me and left the key on and totally wiped the batteries out. I mean dead-dead and it took jump packs and trickle chargers to get it back to life. (I am rebuilding a 1987 International s1700 with a DT366, which is all mechanical, so all these sensors and abbreviations are new to me.) Now for the issue, when we did get the truck started on a jumper pack it would die when shifting into Drive, however L, 2, & R all worked great. So I took it to my local shop for a good solid once-over and they said after trickle charging batteries it idled, ran and drove fine, even in Drive. So I get the list of work needed and bring it home in Drive, no problem. I shut it off fiddle with some lights and close it up for the night. I didn't leave anything on, but batteries were dead the next day. I trickle charged both batteries and truck starts no problem but it dies in Drive only again. But idle, L, 2, & R are no issue. I decide to take it for a spin just to see if maybe that will help. I start in L, step up to 2, then to Drive and all works great, until I stop at the first stop sign, truck lunges a little, then dies. Starts right back up, so I repeat, L, 2, & then D and all fine, shifts into 4th and goes until I hit the next stop, it surges and dies. So I tried down shifting easily, and it doesn't die in 1st when stopping. I brought it home and parked it, haven't touched it since, its been a busy past couple of days. I also see a "Hyper Diesel Power Hyper Brake Whoa!!" unit velcroed to the fuse lid under the hood. also does the 7.3 sort of shut off when you are coasting down a hill? I honestly think it sounds like a marble in a paint can when running, which I love, but coasting down hills, I can barely hear the thing running, it just goes quiet.. until I hit the throttle again. So aside from what I've seen here to check trans fluid, maybe the Hyper brake unit is locking up something? Anything else to look for, any other info to look needed?

 

The injectors quieting down is normal when coasting.

As for the truck stalling when in drive it could be low on trans fluid, a bad TC or PO might have a TC lock up switch somewhere in the truck, or the wiring for the TC lock up is grounded (staffed wiring touching ground.

 

I would try to unhook the hyper brake. It may have a lockup feature that is messed up.

 

Agreed. It is either low on trans fluid keeping the torque conver locked, or someone added a tq lockup switch and it is in on position.

 

Very odd. I started truck when I got home, batteries seemed to be ok, and truck shifted fine, no stall in Drive, not even a hiccup. So I backed up further, shifted into drive, no issues, and was even able to stop in Drive with no issues. I flipped no switches, changed nothing but lightbulbs and it seems to be ok. I'm racking my brain trying to think if I changed anything, maybe whatever was locking up just needed continuous battery power to release?

 

My 96 f250 had a BD engine brake unit wired up inside the dash where it couldn't be seen, PO had added an Edge CS on top of this. That BD unit got hot under the dash causing solder to flow down, shorting things out & causing a flashing OD light. Later on my E4OD lost L&R when the L&R sprag failed. Ended up having overhaul the trans completely. An expensive solder short.

 

So I drove the truck all weekend, Saturday made a few stops, and weather was mid 70s and low humidity. On Sunday it was hot and super humid, made no difference. However I got in truck this morning (nice & cool) and put it in Drive and it immediately died. I drove it to work by downshifting into L at all stops, then upshifting once moving. Let it sit at work all day, got in to go home, and same thing. Made a bunch of stops on the way home and no change. I haven't done anything different, I just don't get it. I tried to unplug the brake assist, but it's wired into the harness and doesn't seem to unplug at all... It was absolutely fine all weekend, nothing changed from when I shut it off yesterday and when I started it this morning.

 

I think we finally figured it out. Even after disconnecting the brake assist, it still did it. So I dug a bit deeper and it looks like it comes down to one of the batteries being bad. There was enough juice to start the truck, from one of the batteries, but the other one is cooked. Cheapo Amazon battery load tester says it's putting out 1/2 the cranking amps, and after charging, it will say it's fully charged, but it doesn't hold the charge overnight. I leave the trickle charger on it all night and truck shifts fine all day, but if I don't, the truck dies in drive the next time I go to drive it.

 

wow. something new learned to add to the list.

 

New issue started yesterday. The truck sat for about a month, it got really hot and muggy here and the A/C has a small leak somewhere (confirmed with gauges). It works for about two weeks, then no longer gets cold, So I haven't been driving it, but yesterday was a lot nicer so I took her for a nice long drive. When I first got out on the road it didn't want to shift into 3rd like normal it took a bit, and then hit 3rd. Then it couldn't decide if it wanted OD or not, then got it up to about 60 in OD and was fine however speedo was not working. It ran and shifted fine for about 20 minutes, speedo seemed to jump to life, then stop again, then it started to shift hard, and at a higher RPM than usual. Made it to work, but on the way home it was fine thru first, second, then hard shift into 3rd again, then OD (still no speedo). But this time the OD light on the column shifter started blinking. I stopped for fuel and light was out on restart, then shifted fine first, then second and again hard shift into 3rd and light started blinking again. Pushing button had no effect. So I got on my road and shut it off again, restarted but this time I shifted into 2nd instead of Drive, ran fine 1st into 2nd and no light blinking, easy shifts, no speedo tho, etc. Seems that whatever is causing the hard shifts is also flipping out the OD light, I read about people having speedo issues and fuse issues with he light blinking. I will look into those tonight...

 

When the OD light flashes, it's telling you that there are codes stored in the PCM. When codes are stored the trans goes to a failure mode to prevent further damage. This includes raising the line pressure to prevent slipping clutches. That causes hard shifts. You need to read the codes to fix this.

I recommend getting Forscan to read the codes. You can download it free at www.forscan.org.

 

If the speedometer is not operational then it will shift weird because it's trying to save its self and od light will flash. Fix the speedo,that will fix the shifting.