Swap is a 05 5.3/4l60e in a foxbody
Using DBW tb and green/blue ecu

Cel code- p2125 throttle/pedal position sensor switch E circuit

Finished up the swap and then pedal quit working.

Pedal did work when I had just the key on and the motor not running.

Then started up the motor 2-3 times and pedal worked fine...l

Took the pedal down and cut a few inches out of it and welded it back up. Remounted the pedal, hooked up the batt and nothing worked with motor on or off.

Disconnected the batt, unmounted the pedal, hooked up batt again pedal worked. Unhooked batt mounted pedal put negative cable back on and nothing.

I unhook the neg batt cable between all of this because I had been pulling battery in and out of this car so battery doesn't stay hooked up.


With the pedal not mounted on the firewall I took the car to get exhaust made, brought her home out the battery in fired the car up. Hit the pedal and the throttle body responded, hit the pedal again and nothing. I've tried clearing the codes with scanner and leaving batt off for a period of time then starting again and still pedal does not respond.

This is the throttle body I'm using


The tac module


The plug inside the car that plugs into the pedal


And finally the pedal


Now when we welded the pedal we sprayed water out of a mister bottle to try and not let the heat travel to the sensor so it didn't get too hot sensor possibly got wet but we dried it up before plugging it in and testing.

The wire ps from the tac module to the pedal were cut and lengthened but I soldered/shrink tubed everything and the pedal worked fine this way.

90% of the time when the pedal worked the motor was not running key was just on the on position. Anyone have any idea what's going on here? Pedal just kneed to be calibrated? Friend that works at calspeed says he thinks it's going into limp mode and just needs tune/calibrated. In limp mode will a DBW pedal respond at all?

 

Do you have a brake signal hooked up to the tac module?

 

No at least I don't know.

I have a worked over harness from calspeed. There's a plug on the harness that goes to the tac module, kohen a different plug on the tac that goes to the pedal.

I do have the tcc wire hooked up along with the brake lamp wire on the harness. Are they tied into each other on the harness somewhere?

 

What I don't understand is the pedal worked this whole time, even after welding. Why would it do this all of a sudden? Would lengthening the wires between the tac and the pedal do anything? Because I cut and lengthened them about 3'

 

sounds like you have a short or something id just double check the wires i put a truck tb on my v6 and ran into a similar prob i mixed up the 2 tps sensor wires coming from the tb connector they were the same color.

 

The harness between the tac and pedal were the only wires I legend, everything else was stock or untouched. I used my multimeter and verified I did not mix up and wires and the pedal worked for over a month. It just recently quit working. It even was working after we cut and shortened and welded the pedal.mwe were sure to make sure the heat didn't get too hot and roast the sensor

 

This code p2125 what is it? What causes it and how do I fix it?

 

The code is for the APP 2 sensor. There are 2 position sensors in the pedal that work inverse of each other. Is that a stop bolt that you have on the pedal? That could be your problem.

 

Had a similar problem. Pedal gave no response after sitting in winter storage. Car would still idle. Repeated pumping the pedal, battery off, cleaned the contacts I'm guessing and it worked again. Bought a spare accelerator pedal position sensor just in case. They are under $40.
BTW, 05 5.3 accelerator pedal position sensor is listed on Rock Auto as one of their most popular parts. Guessing that means they go bad a lot.

 

I checked continuity again and my harness was good even though I lengthened it.

I checked the plug with a multi meter,
Got 5v on purple wire and white/blk wire but
Light blue wire got 1.7 volts on sweeping the pedal
Drk blue wire only gotm3.8 volts

Swapped the sensor on the pedal and got 4.8 on the dark blue wire
And unfortunately I don't remember about the light blue.

For the sensor to work you need 5v on the purple and white/blk

The light blue and dark blue wires sweep. One sweeps from 0-5 volts and the other is 5-0 voltage.

Replaced the sensor and worked perfect, I did notice the internals of the stock app sensor was loose feeling and didn't have tension where the slot of the pedal goes in.

I tested the new switch by plugging it in and turning it with a screw driver. Nothing happened, upon installing it on the pedal it lined up on the slot and had to turn slightly for the screw holes to line up. That was the key for the sensor to reading.

I read another thread where someone had a stock sensor that wouldn't work unless he slightly moved the pedal down then it would read while running, he had to make a sort of bump stop so the pedal wouldn't move so far.

Anyways replace the switch if your not getting the voltage you need at the plug :-) have a nice day

 

Nice diagnostics thats excellent info. as i am just about to put a 05 5.3 DBW,in my car and now i know what to check if i got issues. Thanks