I used these instructions to pull the trouble codes myself on my 1993 Ford F350 crewcab idi diesel with 82K miles on it.
backstory: Bought the truck as former city of Los Angeles truck. Low mileage ex railroad truck. Picked it up and no codes but could have been because batteries disconnected by seller to reset. Don't know.
Drove truck 60 miles RT and after getting off of freeway and when truck downshifted while going up short, steep hill the OD light started flashing. I disconnected batteries, reset light. Next time I drove it, OD light started to flash when it downshifted while climbing hill on freeway (was towing about 3000lbs at the time).
Had trouble codes read at shop who said it "might" be fipl but they need to replace @ $200 and retest to be sure. Unable to wait for parts/repair, I had tranny fluid flush and gasket replaced and drove it 600 miles towing 3000 lbs and OD light started flashing about 150 miles into the trip while going downhill foot nearly off throttle.
At turnaround point I replaced FIPL myself but it may have been too low in adjustment range at .9 @ idle. Drove 600 miles back towing 3000 lbs and OD light started flashing 20 miles into the trip.
Now home: adjusted fipl to 1.2 at idle, 3.8 at WOT. disconnected neg. terminal to reset. Went for short drive and all was good until I went up that same, short steep hill from that first error: as I was lifting throttle while cresting hill, light started to flash (and there were no downshifts at all).
Looks like code 23 is fipl again and code 62 is converter clutch error.
Is this likely terminal? Tranny shifted fine in safe mode the entire trip. Suggestions on what I should check and/or be prepared to replace?
The FIPL should be set at 1.1 to 1.4 volts at idle and 4.1 to 4.5 volts at WOT. Check your ground wire to make sure it is good. If it isn't, or you just want to make sure it stays good, splice into it and run a wire to your passenger side battery ground.
Thanks for the advice-- I really outta get a manual for this thing so I can find things like the tach sensor.
The tach has been functioning just fine, though. I did a sniff test of the fluid and even though it was flushed before this last trip it smells a little less than fresh and does has some grey to it when I dab the dipstick on a shop towel...
noticed when I adjusted the fipl for the 3rd time (engine cold) that it give me a low reading, say 1.2 when I first do the probing but after I do a sweep to WOT it returns to 1.3? or so and won't five me the lower reading again unless I turn ignition off and back on to start the process over again. So what I did was set it for 1.4x and it is now giving 4.1 at WOT. I went and did a test drive-- same loop as I did for the last test drive-- and it shifts a lot later (higher revs) almost like it did in the safe mode, but did NOT start the od light blinking again. (I do toggle off the OD in town or when I'm towing--revs are at 2500 or so on the freeway with it off).
BTW: That .zip file sounds like it might give me some fuel to do some additional diagnostics of the sensors/plugs. Please fwd it my way if it's still available. Thanks!
Yea, so I ended up taking it to a few transmission shops who all told me it needed a transmission rebuild... except for one guy. He said I had a bad torque converter, but because of the amount of work to replace the converter he said most would rebuild the transmission as well. He said I might get another 30k out of the transmission if I just replaced the torque converter.
So that's what I did. I replaced the converter with an upgraded unit, but not the full blown billet one. I also had him install a shift kit, on his recommendation because all I was planning on doing with my truck was towing with it.
The reason it went out? He said probably bad wiring on the trailer lights or the trailer connection. Even dirty connectors can cause it supposedly. He said the torque converter lockup is controlled by the same circuit as the brake lights, so there could be a fluctuation in the current due to a bad ground or something in the trailer and it's not enough to cause a blinking of the brake lights but it's enough to disturb the signal that locks up the torque converter. So I'd been driving without converter lockup while towing.
Later, I did find that the wiring T stub that is sold by Uhaul that fits into the stock wiring harness had a bad crimp/connection. Not sure if this was the cause, but it did involve the brake light on the right side and caused intermittent brake light function.
While all of what you wrote about your failure is true, the majority of pre-1995 diesel torque converters failed and set a 62 code because the lockup piston inside the converter wasn't strong enough. It would crack, which would cause apply pressure to leak. Now there isn't enough clamping force on the lockup clutch and it slips and fails.