A bit long winded, sorry.
Couple weeks ago I got a wrench light and an unresponsive throttle pedal leaving an intersection. I pulled over, shut off the engine and restarted and everything was normal again. This repeated at random throughout the remainder of my commute. Codes were P2104- Forced Idle, P2138 and P2140 which are both throttle position sensor errors. Since I have adjustable pedals I inspected the wiring loom to the throttle pedal and performed this test:

https://www.ford-trucks.com/forums/1...2140-help.html

Bear in mind, I used a multimeter for this test. You can find a schematic for the pedal wiring in your appropriate coffee table book here:

https://www.ford-trucks.com/forums/8...nuals-pdf.html

I found APP3 completely dead and APP1 and APP2 normal. Vref1 and Vref2 both @ 5.2 volts. I then replaced the throttle pedal assembly and had no trouble until a week later i went to the car wash. Wrench light and pedal sensor codes, but the truck drove normally this time. Also, it occurred to me that the first trouble happend when it was raining heavily. I had read elsewhere that there are other sensors that use vref and could be intermittently shorting out, including the map, baro, ebp, icp and egr.
Here's the kicker. While inspecting the map I spotted a box with a yellow wire running across the top of the engine bay. I remembered that it was for the boost fooler I installed years ago and had not been using it for a long time. I also remembered that yellow wire was spliced into the APP2 wire at the PCM. As it turns out it was pinched and partially shorted to ground between the cowl and firewall and my guess is that heavy moisture aggravated the symptoms.
So, there we have it. The very first mod i did to my truck finally came full circle and bit me. Talk about coincidence!


P.S. I don't post much but i spend alot of time reading in these forums. There is tons of good sound advice here and you don't even need to pay to view it. How rare is that! Just wanted to say thanks and give back a little. Keep up the good work.

 

sweet great info. ill have tp remeber this one.