Hello all,
i have 1998 F-350 4x4 diesel with what transmission parts dealer says is a 4R100. has 20 bolts in trans pan. Trans shifts extremley hard when rpms are built up but ok when running low rpm. Truck doesn't seem to have a lot of power. Ces light came on when a hard shift happened (3-4 upshift). went to pull codes after shutdown and no codes detected. Started truck and light did not come back on. couldn't get the light to come back on driving it again. was still shifting hard. I think i may have a bad solenoid pack. Overdrive button in gear handle works correctly, does not flash. also thinking may have bad ecm since computer won't store codes. Any thoughts? Thanks

You could have a solenoid prob but wouldn't that produce a code. My trans is non- computer integrated & I haven't researched your in a while but, proper mechanical function requires a quality fluid in acceptable condition. Viscosity, contaminant particulate %, PH, ability to hold additives in suspension, ect... Condition &/or lack of tranny fluid is hands down the #1 cause of transmission malfunction & catastrophic failure. I'd P/U a can of "TransTune", use as directed & then flush & change filter/fluid. Then see what you have. Personally I switched to synthetic. If you research it, it's a no brainer! Note: When draining, avoid skin contact. The deluged waste fluid smells worse than something that died, came back to life and died again. There is no argument about it's carcinogenic properties. If your ECM is having a problem communicating, there's also a code for that. Check connections at the tranny selinoids. I believe the ECM communicates w/ sensors but only actuates selinoids. Please post when you find out wasup!

I had a 95 f-350 that was doing the same thing, shifting hard but had the overdrive light in the handle flashing. Put a new solenoid pack in and it didn't change anything. Put a new speed sensor in with no luck. the check engine light would come on but never leave any codes. I changed the pcm and all the problems went away. i hope that the solenoid pack in the 99 is the problem, because a pcm for this truck is 200-400 dollars. I 'll change the pack tonight and let you know where we stand.

Well, I got the solenoid pack changed out last night. First thing I noticed is that the trans is a Jasper rebuild. I dropped the pan and foung no metal except for the extemely fine metal on the magnet. Replaced the filter and the solenoid pack. Reconnected the batteries and serviced the trans. It started out still shifting a little firm but was much improved. after two stops though, the trans went back into safe mode, hard shifting again. I never got a check engine light and still did not have any codes after the test drive. Still think the ecm has some problem that it cant code faults let aline a code to say it(the ecm) is at fault. Going to try go get a used ecm and have it reflashed. Don't want to reflash the old ecm for fear it won't take and still malfunction. Timeto get calling! I'll keep you all posted!