Uh oh! You got a code for a ECU malfunction; that could get expensive. But it’s not always that simple. Follow this Real Fix to see how this code was caused by another component on this GMC Envoy.
Vehicle
2004 GMC Envoy 4.2L
Title
P1680, Replaced Accelerator Pedal Position Sensor
Complaint
The customer states the check engine light is on.
Cause
Connected a scan tool and found code P1680 – ECU Malfunction. With the key on, engine off, used the scan tool to monitor live data and found the accelerator pedal position sensor 2 signal parameter was not present. Disconnected the accelerator pedal position sensor connector, visually inspected the connector and terminals and found no obvious signs of damage. With the accelerator pedal in the rest position, used a multi-meter to measure the resistance of the accelerator pedal position sensor 2 between the 5 volt reference circuit and the accelerator pedal sensor 2 signal circuit and found the measured resistance was above the maximum specification of 450 Ohms. These test results verified the accelerator pedal position sensor was faulty.
Correction
Replaced the accelerator pedal position sensor, cleared codes, performed a road test and verified the vehicle operated properly. The check engine light did not illuminate and no fault codes returned.