Ok I'm at a loss. I've been trying to search for the answer for quite some time now and I am coming up empty.
Here is the situation. I have a 1993 Ford F-150 with a E4OD Tranny. The Overdrive switch doesn't light up at all. I have checked all the wires, they are all ok (I think, I tested continuity). The fuse is not blown, I have checked this aswell. The transmission acts like it is in fail safe mode from what I have read, but i dont know if there are any codes because the overdrive light doesnt work and the scanner I have doesn't (I'm assuming) retrieve Tranny codes. It Starts off in Third gear (in drive) and acts like it shifts to overdrive (cant be sure). I can manuelly shift from 1st to 2nd to drive, but that is all the shifting it does. When it was in getting the Emissions fixed the Mechanic said the computer thinks the tranny is in reverse (which doesnt sound quite right, but I could be wrong). I have replaced the MLPS (or Neutral Saftey Switch). I am at a loss. Please help. Thanks.
Edit: Forgot to mention that during the koeo test I get a code 522 Transmission not in park or neutral, which would go along with what the mechanic mentioned above said.
i cant help too much with the tranny problems.....but you can get a new OD switch and trim ring for about 8 bucks from LMC
lmctruck.com page 123 item #13 top center of page
my OD off light does not work either, and my tranny seems to shift and function fine except for hard shifts sometimes, hard down shift sometimes from OD to 3rd, prolonged shift points (sometimes close to 3k) depending on throttle position, and sometimes needing to "feather" the gas to get it to go into OD......
....ok, maybe its not working fine after all ....lol
but i did just order a new switch and cap for it
EDIT: the button works on mine, just the light is not working
As for the trans issues, when the MLPS is replaced, it needs to be in the correct position. I think yours may need adjusting. I did a quick search on here and didn't find the procedure, maybe someone else will have it and post it.
Thank you but the adjustment for the mlps is pretty straight forward line up too lines, tighten down, and your good. I have also made sure it was getting power. Ive done a lot of searching and have yet to come up with a solution. Google is my friend when it comes to finding something out. I do have a decent amount of mechanics experience although i am very far from being an expert mechanic.
Thanks. im going to look around and see if there is another way to adjust it cause when it gave that code thats what i was thinking too. I adjusted the old one and still same code so i bought a new one cause it was old, but still get the same code. Also when i was going throught the steps of testing the voltage all the voltage readings were out of tolerance on the high side. Could that have anything to do with it? Could my mlps be getting too much voltage?
Going from memory (and keep in mind I'm not a pro mechanic either), the MLPS works like a variable resistor. Each different position yields a different ohm reading, thus decreasing or increasing the voltage the PCM sees out of the switch.
So, yes, if the MLPS is putting out higher voltage than expected, it'll confuse the PCM.
That said, I'm not sure what the voltage should be that's fed to the MLPS. I'm guessing 5v like most other sensors, let's hope someone can come along and clear this up.
From what i have read it is 5v reference than as you said the sensor changes it as you change gears. I just thought of something i havent even checked the voltage on the new sensor. I will do that today and post my results.
So here are my voltage readings
P- 4.78 Tolerance 3.97-4.85
R- 4.39 Tolerance 3.25-3.96
N- 3.93 Tolerance 2.55-3.11
D- 3.33 Tolerance 1.88-2.30
2- 2.56 Tolerance 1.23-1.51
1- 1.50 Tolerance 0.61-0.75
As you can see way to much voltage. I took the switch off and tested the ohms and they are well with in the limits so the switch is good. That is probably my problem with the code 522, but why does my overdrive switch not work? And why would i be getting too much voltage? I do have a Haynes and I am thinking of getting a shop manual. If you have any sugestions let me know. I cant afford to take it in and have it diagnosed, but its starting to look that way. If the tranny needs rebuilt I will be doing it my self.
Would my switch not working and too high of voltage have to do with a bad ground? If so where and how would I find the bad ground? What would be the best way to find it?
Last edited by ngmead; 04-06-2010 at 10:24 PM.
Reason: Adding Info
Get a wiring diagrahm and find out wich one goes from the pcm to the over drive cylonoid. Take a test light and connect the clip to a positive lead. With the key in the on position, and the truck in the drive position, touch the wire with the test light, and it should alluminate. If it does not, than you are not getting a complete ground loop from the pcm. Three options, broken wire, bad pcm, bad cylonoid block.
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