Howdy Subford and fellow enthusiasts, I finally got my hands on 2 PSOM's from the salvage yard. With already having replaced the VSS and the rear diff fluid/inspection of the speed gear it shifted pretty decent for the few miles I drove it but the speedo was all over the place. So, I replaced the PSOM with 1 of the 2, I drove it about 20 miles and shifted great. Speedo was working and all seemed good. I then replaced the PSOM with the 2nd one I got and it did even better, had lower mileage also. I took it on numerous test drives and did terrific every time. Today I took it to work (45 min) one way, and I noticed small hesitations and semi hard shifts. I drove it around at lunch and it performed great with 1 semi rough shift. On the way home I got up to about 60mph and it clutched itself, hesitated and slammed back into gear. It drove kinda funky like that the rest of the way. Almost home I experienced an insanely hard shift from 2nd to 3rd... Do any of you knowledgeable Ford Gods have any idea what I'm up against??

 

Sounds like the transmission lost the information signals from the PCM and defaulted to limp mode.

I would take a look at the plug on the passenger side of the transmission. Check the wires going into the plug as they brake loose there sometimes.

If ever thing looks OK with that plug the TR sensor may be bad on the drivers side of the transmission.

If that is OK I would open up the PCM and see what the caps in it look like. The PCM might be bad in other words.

 

Thanks for the quick reply man. I appreciate that I can rely on an answer to come back before too long. I'll try to tear into it tomorrow and see what I find.

 

As far as I can tell, the transmission wires look fine. All is in it's stock wire casing. The two connection points on the driver side are connected and have no broken wires. The passenger side connection looks good and can't see any broken wires there either. I followed the wiring from the trans back to the rear end and beyond to the bumper. The wires along the frame between the trans and rear end have been spliced into in two different spots. The first is spliced with quick connectors to power some tacky undercarriage lights that I disconnected (they didn't touch the twisted VSS wires) and again to power some very large 7 prong outlet in the side of the bed (also not touching the VSS wires and used quick connectors - some wire exposed). Further behind the rear end just before the bumper a 6 prong outlet is spliced in also using quick connectors and looking pretty shabby. The driver side rear brake/turn signal wires have been tapped into also, looks to be powering a trailer light connector. A license plate light is also spliced into some wires behind the spare tire close to the bumper.

 

1.Is the only way to test the TR sensor replacing it?

2.What is the PCM and what does it do? Where is it located?

Don't know if it makes a difference but I've noticed that the ignition somewhat free spins. It will turn backwards further than it should and it can miss align so that the key will not go in without spinning the outside piece to re-align the holes. Its also somewhat protruding from the column in a weird fashion... Seems loose..

 

1. Use an Ohm meter and check the resistance in each position of the stalk.
Start at the bottom left of the page posted below.

2. The PCM shifts the transmission and regulates the oil pressure in it.
The PCM is located at location A-8 in the image in post #58 above.




Use the top image below, check between pin 7 & 6:

/

 

Thanks for the walk-thru's. I'll have to wait until tuesday to get my multi-meter from work to test it. As soon as I get that info I'll post it.

 

Okay, not too sure if I'm doing this right but.....
I connected my multimeter up to the harness and set it to ohms first with the positive lead in the #7 and the negative lead in the #6 and I got a reading of 1387 in park. I then turned the key forward enough to change the gear and got the same reading of 1387 in every gear. When I turned the key one more click forward so that the accessories had power the reading went to 1 in every gear. I then turned the key off and changed the leades around to positive in #6 and negative in #7. Using the same method as before, all gears showed 379.

I'm not sure what the "jacks" are that are referenced in the instructions above. It said to connect one lead to the TR jack and the other to the return jack... I'm confused.

 

It sounds like you were testing the harness and not the MLPS.

Ray

 

Well then in that case, how the hell does one go about testing the sensor while in the transmission?? There is no physical way to see the top of the sensor to even start to tell what the leads are touching??

 

You should not have turn the key to on as that would send voltage to the meter and ohm meters do not like that.
You should have had the wiring to the computer disconnected during the test.

 

You can disconnect C103 under the hood and do the ohm reading there.

Location of C103:


C103 pinout:


/

 

Well crap..... Wish it said something about all that in the instructions from earlier. I am good at most mechanical repairs but when it comes to electrical I'm not exactly knowledgeable.

By looking at the diagram you just posted, where am I connecting leads and what is the process in which I should be doing this? Also what kind of reading am I looking for to determine that the sensor is good/bad?

 

You connect to pins #5 & #6 of connector C103.

TP or MLPS testing.

 

This evening I plugged my multimeter into the #5&6 position of the female connector under the hood. When first connected (P) was reading 1 until I turned the meter to the 200k position then it varied from 23-29. (R) read 1453 steady. (N) read 753 steady. (D) read from high 400's all the way passed 2000. (2) read 212 steady. (1) read 87 steady. I went back to (P) and it bounced around in the high 70's while in the 200k setting. Then I went back to (D) a couple more times getting a reading of 410 then 424.

So, what I saw was a major inconsistency both in (P) and (D) even tho (D) eventually ended up in a good range.

Any thoughts??
Once again subford, thanks for the diagrams!