[Berlaga1]

Hello! I have a 2014 ProMaster 2500. The Electronic Throttle Control warning light (red “lightning bolt” in parentheses, blinking) has been coming on and off for about a year. Last month I drove 1500 miles and it never came on, but this month it comes on every time I start driving, after a few minutes. Acceleration becomes irregular / weak. Two different DTC scanners show the same trouble code, P2122 (Accelerator pedal position sensor 1 circuit low). I replaced the pedal (which has these sensors built in it), with no result. An electrician tested all voltages from the pedal to the computer, and he also tested the wire harness and said it was fine. After that, he gave up and said he couldn’t find what triggers the code. (Of course he cleared the codes several times, after doing his tests and after I test-drove the van.) He suggests having the van's computer reprogrammed / software updated by a dealer. Before I go to the dealer, who will start with the same tests but will charge me much more, I thought I’d ask here - did anyone have this issue, and, if you finally could resolve it, what caused the problem? Thank you in advance for your feedback.

 

[el Jefe]

Theory of Operation

Accelerator Pedal Position (APP) Sensor applications today use Induction/Hall Sensors (non-contact).

The Electronic Throttle Control (ETC) system uses two Accelerator Pedal Position (APP) Sensors to monitor the accelerator pedal position. The APP Sensors 1 and 2 are integrated into one assembly located at the pedal assembly. Each sensor has a 5 volt reference circuit, a low reference circuit, and a signal circuit. The Powertrain Control Module (PCM) reads the two signals individually and then compares the two signals as a redundant check of the pedal position. The APP 1 signal will fluctuate somewhere between 0 volts and 5.0 volts. The APP 2 signal will fluctuate somewhere between 0 volts and 2.5 volts. The fluctuation of the two sensors should move proportionately. When operating properly, the voltage reading of the APP 2 will always be approximately half of the voltage reading of the APP 1.

The signal for APP 2 is also used by the PCM for an internal ground check. This test runs a couple of times per second and is the reason why the APP 2 signal spikes to ground regularly during normal operation. If graphing the APP 1 and APP 2 signals for diagnostic purposes, view the figure below to see how the signals will look on a normally functioning APP system."

This is only part of what is in the service manual. There is a very lengthy troubleshooting procedure which requires a nifty $900 tool:
"
CAUTION:
Do not probe the PCM harness connectors. Probing the PCM harness connectors will damage the PCM terminals resulting in poor terminal to pin connection. Install the GPEC Diagnostic Adaptor to perform the diagnosis."

 

[Berlaga1]

Thank you for your reply. I actually have the complete service manual. I know that the troubleshooting procedure is long and complicated. That's why I hope someone had this problem, had it fixed and knows a solution.