I have a 1991 f150 4x4, 5.8 v8 with e4od transmission. It will not shift into drive but can put in 1,2 or reverse manually and it works fine. I did a dtc test and got codes 654 and 634, for the mlps and the vss. I replaced both sensors and adjusted the mlps to correct position. Then I checked codes again and got the same reading, even though both sensors are brand new. The truck still won't go into drive. Does anyone know why the pcm is still giving these codes even when both sensors have been replaced and adjusted correctly?

 

Check the wires to the sensors. I ''think'' you should have 10.5 volts to the vss. Replacing sensors don`t fix bad wires. I think you got more problems than just the sensors but check those first. And reset the computer.

 

I did check the connectors at the sensors and cleaned them, but of course it didn't help. I traced the wires down under the truck and all looks well. Do these sensor wires run up into the steering column and then to the pcm. Is it possible to have a broken wire in the steering column or maybe the pcm is just bad and can't read the sensors input even though they are new.

 

Thats why we test at the connection first than work back.

 

I checked for voltage at the vss and mlps. At the vss I get 5 volts and at the mlps I get 4.9 volts on one wire and 11.6 volts on another, but nothing on the other 6 wires. Do you know what the voltage is supposed to be at these sensors, or do you know how I can find out. I also took it up the road just to see if it did any different after I checked these sensors. I didn't realize it until I got back, but I had forgotten to plug the mlps back in, but while it was unplugged it shifted almost perfect, started in 1st then it shifted into 2nd and on in to Drive just like it is supposed to. I thought I had accidentally fixed it by fixing a bad connection or something, but when I stopped to turn around it started out in 2nd not 1st, but it still shifted into Drive just fine, so when I got back I remembered to connect the plug back to the mlps, then tried it again and back to the way it was before, got rev., 1st., 2nd. but no Drive again. Any help would be greatly appreciated! Thanks

 

is your MLPS adjusted right? im surprised your truck even shifted without it hooked up, didn't know it could do that lol. id guess your MLPS is bad.

 

I thought MLPS was bad too, so I buy a new one and hook it up, then adjust the marks to align together in Neutral, like it says, and still get codes 654 ane 634. It surprised me too that it shifted w/o MLPS hooked up but it did it for only about 10 minutes then it would take off in 2nd then shift into Drive. This tranny problem is really driving me crazy! I'm thinkin' maybe the EEC-IV is just burnt up.

 

634=manual position sensor voltage higher or lower than expected.
654=not in park during koeo self test.
This is what my book says your codes are. Not sure if this helps or fixes your problem.

 

Would anyone happen to know what voltages would be present when testing the MLP sensor connector with key on? Checking to see if power is going to the sensor at all.

 

They say to use a breakout box and measure between pin 46 and 30. Between the pins it should be 4.75-5.25. I don`t see a pin 30 in my info, must be on the breakout box. I do see a pin 46. Your mlp is tested in ohms in each gear.