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2004 Ford Expedition 4r70w

Just Try It1 Just Try It1
Moderator | Posts: 2796 | Joined: 08/14
Posted: 02/10/19
12:54 AM

without the VSS signal the computer does NOT know how to handle the shift points..

there are 2 speed sensors plugged into the side of the transmission..

one is closer to the middle of the transmission case and one is near the back of the main case..

the rear most one is the output speed sensor.. i don't think this is on the rear end but it could be . it was on earlier models.

you will want to clean the area.. disconnect the bolt holding the bracket and the speed sensor in.. you will want to pull the speed sensor and examine the tip for impact damage ..

 you will want to verify that one of the 2 wires has probably 5 volts on it with it unplugged.. that will be the Dark blue and yellow striped wire..

the other wire should be grounded thru the PCM this will be a Brown and LIGHT GREEN stripe wire..

if you had a way to backprobe the connector with it hooked up.. you could do that to the Dark blue and yellow wire and slowly rotate the drive shaft in neutral with the key on and a volt meter hooked up measuring the voltage to ground.. as you rotate the voltage should go up to 5 volts and then back down to 2 volts and back to 5 volts and back to 2 volts.

inside the transmission are either notches on a gear or gear teeth.. as the output speed sensor core aligns with the gear teeth in the transmission the voltage drops below 2 volts usually.. when the gap between the gears lines up .. the voltage comes back up to 5 volts ..

these wires take a lot of abuse down in the wind rain and slush.. plus they can be exposed to rodents who are hungry..

you are really going to need a scan tool to read the codes.. and to look at the speed sensor signals..  

Just Try It1 Just Try It1
Moderator | Posts: 2796 | Joined: 08/14
Posted: 02/13/19
08:15 PM

SPLICE S138  on CIRCUIT 359 which is a GROUND circuit thru the PCM..

these are Grey and red wires.  check your resistance to the number 2 terminal Grey and red wire on the manual lever position sensor/neutral safety switch..  its also connected to both the rear oxygen sensors.. grey and red wire.. for the sensor ground

the splice continues to the PCM on connector C175T  cavity 27...

circuit 1202 is a Brown and Light green wire to the Output speed sensor pin 1... this is also on the circuit described above..

the positive side would be a Dark BLUE and yellow wire into Connector C175T  Cavity 25.

that connects to the Output speed sensor cavity 2..

i would love for you do to a voltage drop test.. to the output speed sensor Brown and light green wire to the transmission case with the engine running..  you should have less than 0.04 volts.  if you flip over to resistance you should have less than 1 ohm..  

the Dark blue and yellow wire should have variable voltage up and down when you rotate the drive shaft by hand with the key on..  by back probing the output speed sensor connector..  

Just Try It1 Just Try It1
Moderator | Posts: 2796 | Joined: 08/14
Posted: 02/14/19
06:29 AM

lol.. i completely understand you..  this is not a circuit that most non professions will mess with..

you may still want to do some research on or  those are subcription services that have the professional info for a fee..  

i can't afford to subscribe for each question.. as i don't charge nor do i get paid by this site. i just moderate it like its my own.  its made me a better mechanic over the past 11 years i have been on it ..

images to help.. edited by me myself and I..  hopefully these will help..



these are linked directly above and when you click on them there they will open full screen i hope..  

Just Try It1 Just Try It1
Moderator | Posts: 2796 | Joined: 08/14
Posted: 02/14/19
03:01 PM

you can only run ONE... the dark blue and yellow..

the brown and light green when it becomes grey with a red stripe feed a lot of things..

i would highly advice spending the 30 bucks on a subcription to eautorepair and getting access to the full service info.  

Just Try It1 Just Try It1
Moderator | Posts: 2796 | Joined: 08/14
Posted: 02/15/19
03:52 PM

good luck.. post what you find if you can.  

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