SureTrack Real Fix: Pedal Diagnostics

When a check engine light comes on and a code P2127 appears, it’s time to start the process of elimination using more diagnostic tests. Diagnosing this type of fault is made so much easier with Triton or the Zeus as the live data can be used to monitor the accelerator pedal position. The Scope enables you to check powers and grounds via the digital multi meter and the Lab scope shows a visual of the faulty accelerator pedal position sensor.

Vehicle
2012 Mercedes-Benz Sprinter 2.1L Diesel

Title
P2127, Replaced Accelerator Pedal

Complaint
The customer states the check engine light is on.

Cause
Connected a scan tool and found code P2127 – Throttle/Pedal Position Sensor/Switch “E” Circuit Low. Used the scan tool to monitor live data, performed a throttle sweep and observed the accelerator pedal position sensor parameter did not maintain the specified correlation as the throttle was swept. Visually inspected the accelerator pedal position sensor wiring harness and found no obvious signs of damage. Used a multi-meter to check for the presence of voltage and ground at the accelerator pedal position sensor and found both were present. Backprobed the accelerator pedal position sensor, monitored the sensor signal on a lab scope and found the accelerator pedal position sensor signals observed on the lab scope intermittently dropped out as the throttle was swept. These test results verified the accelerator pedal position sensor was faulty. The accelerator pedal position sensor is integrated into the accelerator pedal and is replaced as an entire unit.

Correction
Replaced the accelerator pedal, cleared codes, performed a road test and verified the vehicle operated properly. The check engine light did not illuminate and no fault codes returned.