I just installed a new MLPS on my 1990 F150 4.9L 2 W/D with the E4OD Trans.
Now the problem is it will start in Neutral but not in park...I adj. it so that the marks line up and now I'm not sure if I replaced the wires correctly when I swaped them over to the new connector....Does any one have a wiring diagram for it to tell me what color wire goes to which pin??? Or can someone just tell me what the colors should be and in what place on the new connector...

Thank you for any help....I have searched all over the post's and had seen a Diagram for it somewhere but now I cannot find it...

 

I also drove the truck and I must say the shifting in gear is a lot firmer....

It still wont start in Park but hopefully someone has some insight....

 

If the truck starts in neutral, your wiring (for the start circuit) is probably fine and the MLPS neutral/drive switch is fine. You just need to fix the adjustment.

Step one is to adjust the shift linkage. Shut the engine off. Jack the truck up. Crawl under and loosen the shift linkage bolt that secures the slotted arm to the bellcrank (just in front of the trans). Put the shifter in "Drive" (OK, it is technically "Overdrive" for this trans).. Hang a weight or get a helper to put a downward bias on the shifter so it is held firmly in the down position in the "Drive" detent.

Crawl back under the truck. Move the trans shift arm all the way to the back (the "1" position). Now move it forward two clicks. Double check that the lever in the cab is still in "Drive". If it all looks good, tighten the bolt in the shift linkage. Put the shifter lever back in "Park".

Step 2 is to adjust the MLPS. You are supposed to use a special tool, but it isn't that critical. Look closely at the side of the MLPS (take it off the trans if you have to). There is a small notch in the metal case about 1/4 inch below the top of the MLPS, roughly right in the center front-to-back. I believe this is the notch for locating the special tool.

Loosen the two capscrews that secure the MLPS. Rotate it about the transmission operating shaft until the small notch at the top is centered on the shaft. (The transmission operating shaft has two parallel flattened sides on it. Sight along the two flattened sides. The small notch should be centered right in between the parallel extension of these two sides.)

If your MLPS is like mine, the correct positioning is near the limit of the slotted mounting holes. If you can't figure out the above, try loosening the MLPS retaining capscrews and rotating it (gently) as far as it will go in each direction. Try it both ways, one of them should work. (I believe you will want it fully counterclockwise, but I'm not sure.)

The wire coming into the MLPS from the start switch should be white with a pink tracer. The wire going from the MLPS to the start solenoid should be red with a light blue tracer. The two wires should be in the same row of 4 pins of the connector, at opposite ends of the row. I think it is the right hand row, looking in to the harness connector with the pointy end of the connector up. (But I may have this mirror-imaged).

If you have doubts about the wiring, you should run a KOEO and KOER test, as well as drive the vehicle around and check for memory codes later. Usually the PCM will make the trans shift harder, not softer, if it does not like the info it is getting from the MLPS.

 

I do have the correct adj. on the sensor marks but I didn't relize that I had to adj. the
linkage...I will try and hopefully it will solve my problem...

 

I adj. the linkage and still have the same problem.....It will only starts in neutral....The marks on the sensor are lined up in the correct position.....Mine is the same as your turned all of the way counterclockwise....Is there any where that has the diagram of the wiring and color codes....?????????

 

I added a picture of the connector pinout to my gallery. Be advised that this is from the data for a 1991 F150 5.0, and may not correspond to the retrofit kit from the later years. Circuits 32 and 33 are shorted together by this switch in the drive and neutral positions. You can pull the MLPS off and probe the pins on the sensor with an ohmeter. Turn the center of the MLPS to the park position. Two pins should show a near zero resistance to each other -- those are the ones that need to be connected to circuit 32 and circuit 33. I believe all of the other pin combinations will have a higher resistance than these two.

Update: I added the MLPS from a 1996 Explorer to my gallery. It is fairly likely this is the same as the retrofit, but not certain.

I have photos of the original MLPS in my truck, and may add them later it it will help.

 

I seen the pic. and will be checking it in the mourning .....I believe that is how it is hooked up now....If it is differant I will change the wiring if it is the same I will be returning the part for a new .....Thank you for all of your help.....

I will post on the outcome of what I find....

 

I added some more pictures to my gallery. They show the MLPS installed on the side of the trans, and adjusted so that it works OK for me. The trans operating shaft is in "park" in these pictures.

 

The diagrams worked....I had one of the wires in the wrong terminal....Thank you for your help.....

 

I wouldn't have guessed that it was possible to mis-wire the MLPS to get the result you did. The park/neutral portion of the switch appears to be the only pathway with a low enough resistance to allow the start circuit to be completed well enough to energize the solenoid. So I figured that if neutral works, park should work also.

I see from your experience that I was mistaken. Glad to hear that it works now; I may puzzle for a while over how this could happen...

 

Does all the great information on this MLPS subject apply to my E150? Thanks.