Some of you have found that your Manual Trans 03 or 04 trucks do not have the APPS assembly bolted to the side od the engine. Yours will be under the battery tray. You'll have to remove the drivers side inner fender well to access it.
I used to sell these sensors (OEM Mopar) but most every customer that purchased one, it did not solve there problem. There check engine light was still on and they felt the NEW sensor was defective. That lead to warranty requests, upset customers and a loss on my end.
If you are having an issue with yours and want to replace the sensor here is the Mopar part # 53032456AE if you do a google search just use the part # and you'll find one cheaper than your local dealer.
Here is technical info on how it works and how to test it. Below is a Youtube video
The under battery APPS consists of 2 variable voltage signals for acceleration. Below is a bench test using a 5V power supply and two voltmeters. The left meter is APPS signal #1. The right is APPS signal #2.
Notice that the APPS signal #1 is always double the voltage of APPS signal #2.
If want to test yours, get 2 voltmeters and back probe your ECM plug. APPS signal #1 is ECM pin #14. Signal #2 is ECM pin #16
NOTE!! Both of these are checked on the 60pin connector(the one closest to the front of the truck).
Your start and finsh voltage value may be slighly different. The important thing is ECM pin #14 is double the voltage of ECM pin #16, the entire travel of the accelerator pedal.