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decided to do some maintenance on my 1991 F350 4X4 7.3 diesel. drained and replaced oil and filter in tranny. about 4 days later having probs. slipping real bad in 1st and wont shift to 2nd and so on. it has reverse but it feels snatchy, like the feel of truck in 4 wheel low lock. noticed that when the truck is started it seems to slightly lunge forward. also my anti lock light is on in dash. i did not drain the torque converter. i replaced the vss sensor but anti lock light still on. i did get the old seal from filter out before putting in new on. any sugestions would be appretiated ty.
Did you put the right fluid in? It should take Dex3. Also is the tranny full? I wouldn't think not draining the torque convertor would affect anything. If this doesn't fix your tranny i'd say its either the MLPS or your PSOM. I had to change both of these in my truck, now it shifts like a champ. As far as electronics, You'll have to scan your truck to see why the abs light is on.
good luck dude
yeah i put in dex3. im new to the E4OD so im not sure what MLPS and PSOM is. i did have a guy try and scan my truck but he said there must be a ground somewhere loose because it wont read. ive had no probs w/ wiring so im not sure about his assessment. someone did tell me that u have to check level 3-4 times over a period of a couple days to make sure its full. i will check again.
You might want to look at the scanning again. If you can't get a response from the processor it may be a problem. You should get a pass code. If the electronics are not working the trans will be in limp mode, the OD light may flash or not. The shop manual has a troubleshooting chart for no codes. Hope this helps...Don
he has a newer model F250 (believe 96-97), when mine didnt read he went to his just to test the scanner and it wrked on his. my brother has a 1991 F250 same moter trans and the guys scanner wouldnt wrk on his either. is it possible that the scanner he had might not read the earlier models?
i find it hard to believe w/ 2 1991 trucks sittin there that it wouldnt wrk on ours but would on his (and theres nothin wrong w/ the F250 ). but...... if i did look for a ground any suggestions on where to start? there is many, any specific ones for the tranny or computer? thanks again.
The scan tool for a 96+ is different than for a 95 and prior (usually). Those that do have dual capavility require special cables as part of the arrangement.
Pre-95s can be scanned with nothing more thab a paperclip. Instructions are here, on this site.
1991 is pre OBD2. A newer reader might not work. The plugs are different. You can use a analouge voltmeter or test light and a jumper. You count sweeps to find what code it is. Should not be hard to find a procedure, you will also need some diagnostic charts.
Has the fluid ever been changed in the tranny before? If not when you added the new fluid and filter all it did was soften the seal again and make them brittle. If that is the case you are going to need to rebuild.