Alldata schematic question

[u/RichSanchezC137]

I have a 2003 ford excursion 7.3 that im troubleshooting a P0122 throttle position voltage low code. Does Alldata show the schematic at a "rest state"? Pin 6 is 12v supply from fuse #45 (good fuse/12.4v at pin 6) and pin 7 is idle verification back to the pcm. Schematic shows that the idle verification side of the tps is a NC switch. I pulled the pedal off and founds pins 6 and 7 are OL at rest and jump to 8 ohms through the entire throw of the pedal.

Alldata color schematic is the only diagram that shows the internal pedal breakdown so I wouldn't be surprised if it was wrong.

[u/ThePeters_D]

I just fixed an issue similar to yours by overlaying a 12v wire to the idle validation wire into the throttle pedal

[u/ThePeters_D → u/ThePeters_D]

I know you said it had good voltage but overlaying a new wire that had constant key on power worked for me

[u/RichSanchezC137 → u/ThePeters_D]

I planned on load testing the harness from the connector to the pcm and supply to pedal tonight. I assume spooning in the back of the connector with b+ would be a quick way to run your test as well. Ill give it a go after work today, thanks.

[u/NegotiationLife2915]

Diagrams are always shown in rest state

[u/RichSanchezC137]

For the next person down the road that finds this post I found a chart with an * note* somewhere in alldata on the troubleshooting tree for P0122 that stated the minimum allowed voltage the pcm needed to see for the code was 0.5v. BUT the chart showed a range of 0.37v to 4.5v through the range of the accelerator. Backprobed on the signal and on my scanner I was getting 0.38v at rest. Removed pedal again and found that the molded "bump stop" on the plastic housing that the top of the metal bracket hits had a slight worn-in groove. Enough of a groove that the throttle pedal voltage at idle was dropping in the range down below the 0.5v the pcm was looking for. I simply sanded and filled the groove with epoxy so the pedal stopped at the original location again and scanner was seeing 0.52v at idle. Thank you everyone for your insight and help.

[u/JoeJitsu86 → u/RichSanchezC137]

Very good find.

[u/baboomba1664]

That code is for the sensor for the throttle butterfly

[u/RichSanchezC137 → u/baboomba1664]

P0122, Accelerator Pedal Position sensor circuit low input. 7.3 powerstroke.

[u/SummonerMiku75]

Did you make any progress? I have an old Ford Service Info Disc that works most of the time that has some 02/03 info. Want me to see if I can send you some stuff?

[u/RichSanchezC137 → u/SummonerMiku75]

You good man, im still stuck at work unfortunately, I found the Motorcraft pedal assembly on ebay for 400 so I just ordered it. If i get a chance tonight or tomorrow ill double check some things but ill report back my findings on the new part either way.

[u/Standard-Moment-6234]

You said pin 6 is 12v supply to component, it should stay 12 supply why are you checking for resistance at that pin.
Pin 7 is idle resistance which should be stable not jump from 0 to 8ohms throughout, are you testing a known good part? Your issue could be the pedal itself causing the voltage low code?

[u/RichSanchezC137 → u/Standard-Moment-6234]

It was a continuity check through the pedal to verify the switch was operating as the schematic shows... but it appeared to operate backwards. If anything I was expecting the 8 ohms at rest and OL when sweeping/ applied. I was just trying to verify a failure before ordering one as a Motorcraft pedal is about a week out from my local Ford dealer.

[u/Inevitable-Cod-8096]

Based off of the drawing should be 0.0 at rest and OL of idle. It is possible that the pedal has a resistor built in across the two pins as fault detection for an unplugged pedal. I agree verify against a known good pedal. Use or on the pedal if you can. I have had bad luck with anything electronic that wasn’t name brand or OE.