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Can you detail as to how you're making your resistance and voltage measurements (for example, where are you making your measurements). Also just making sure, you're making your resistance measurements with the truck off, correct?
Truck is off, although I have verified the same results yesterday while actually driving it and watching the volt/ohm meter. To simplify, red test lead is connected securely to the 5V in or MLPS wire from the PCM, while black test lead is connected securely to the signal return wire (verified by connecting directly to the neg battery terminal).
Resistance measurements cannot be made with the system energized or with the sensor in circuit (plugged in). You should also unplug the MLPS while making resistance measurements, since with it plugged in, you'll be measuring the resistance of the entire system.
Plug the sensor back in, and go for a drive with your meter hooked up:
- Hook your meter's red lead up to the 5v input at the sensor, and then hook the black lead up to chassis/block/battery ground. Monitor the voltage - it should be 5 volts at all time.
- Next, hook your meters red lead up to the signal return line, and the black lead up to chassis/battery ground. It should read close to 0 volts at all times.
Didn't have time to go for a drive, but the resistance values of the MLPS when unplugged are as follows...
P = no value
R = 1441
N = 730
D = 399
2 = 210
1 = 087
and obviously no voltage values.
So, apparently with regard to resistance values, my MLPS is good; near perfect? Also, one last check of error codes reveals only a code 67. So with a new solenoid pack, new harness connectors, etc. etc. I'm guessing the culprit MUST be...
I'm going to see if I can get these parts from Radio Shack or somewhere locally, if not I'll order them and try to do the repair myself. It looks like it would be an easy repair but even if I fail I think a new PCM is around $100. I have researched this problem on every Forum I could find for 6 months now and have found that although failure of the PCM is fairly common, it don't look like that has been the culprit in the majority of cases with the shifting issues I've had. I really appreciate your help in figuring this out and I will post results of the repair or PCM replacement to confirm. Something else that I have found very often to be true and has been very frustrating is that when people do figure out what the problem is they don't post what it was or how they fixed it and that leaves the other people needing help still in the dark!
If you find a radio shack that has the exact farad & volts, you've got a unique one. Everyone here (myself included) save somebody in FL, has bought them on ebay.
Like I said in post 4#, mine was a bad PSOM on top of leaking caps.
I appreciate the info and you are right, I called Radio Shack and they don't carry any 105 deg. capacitors but the guy was helpful and advised me that a lot of the ones you get off of Amazon or Ebay are counterfeit (lower temp) and won't last so I ordered what I needed from Mouser this evening.
I did read your thread and it seems like the psom is the main fix that you found but if I'm not mistaken my truck does not have that, being a little older than yours. I'm not 100% sure if that is correct but I do know there are no wires going to my speedometer at all other than to the lights.
Edit...
I actually have your thread confused with another one. I'm reading your thread now... looks like good info.
So I got my capacitors in today and replaced the two 47uf and since I was in there and had the extra capacitor, I went ahead and replaced the one 10uf, too. Shifts are smooth as a luxury car now and perfect. The truck has never shifted like this since I've had it. I've only went on one test drive so I hope it stays this way!
What I've learned...
1. You have to check resistance values of the MLPS (and any other sensor too probably) with it unplugged, voltage values with it plugged in
2. Make checking the PCM one of the first steps, NOT the last! It's super easy to just take it out and look at the board.
3. Safe mode on my e4od did not make the OD on/off light flash. Mine has apparently been in safe mode since I bought it but I didn't know. I just thought it shifted a little hard or maybe someone had put a shift kit in it.
So for anyone who may be looking for help with a similar issue and sees this, my truck is a 1990 (made in 1989, wire colors correspond to 1989 as well) F-150 XLT Lariet 5.8 with e4od 4x4.
Thanks for everyone's help and if it turns out that this did not fix it, I'll let you know.
UPDATE... Just for others reading that are having the same issues, the capacitors fixed my problem 100%. It's been five months now and the truck still shifts absolutely perfect with no new issues.
What's funny, is that it used to believed that the computer in these trucks was either something that worked, or it didn't work. However, these failing capacitors are introducing all kinds of weird, bizarre and explainable issues.
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