Diagnostic trouble code (DTC) information ECM-950C

Condition

Fig 1: Identifying Accelerator Pedal (AP) Position Sensor

Courtesy of VOLVO CARS OF NORTH AMERICA.

The engine control module (ECM) checks the pulse width modulation (PWM) signal and the analog signal from the accelerator pedal (AP) position sensor.

Diagnostic trouble code (DTC) ECM-950C is stored in the engine control module (ECM) if the engine control module (ECM) registers a fault in the signals from the accelerator pedal (AP) position sensor.

Diagnostic trouble code (DTC) ECM-950C can be diagnosed when the ignition is on.

Substitute Value

Filtered accelerator pedal signal when accelerating
Acceleration is ignored when braking
In the event of a detected fault in one of the signals the other signal is used.

Possible Source

Analog signal too high:

Short-circuit to supply voltage in the analog signal cable
Defective accelerator pedal (AP) position sensor.

Analog signal too low:

Short-circuit to ground in the signal cable
Open-circuit in the signal cable
Open-circuit in analog ground
Open-circuit in the power supply
Defective accelerator pedal (AP) position sensor.

Pulse width modulation (PWM) signal too high:

Short-circuit to ground in the signal cable.

Pulse width modulation (PWM) signal too low:

Short-circuit to ground in the signal cable
Short-circuit to supply voltage in the signal cable
Open-circuit in the signal cable
Open-circuit in the power supply
Open-circuit in the ground lead
Defective accelerator pedal (AP) position sensor.

Faulty pulse width modulation (PWM) signal:

Loose connections or contact resistance in the terminals on the pulse width modulation (PWM) signal cable
Interference on the pulse width modulation (PWM) signal cable
Defective accelerator pedal (AP) position sensor.

Comparison fault:

Loose connections or contact resistance in the terminals on the analog signal cable
Fault in the power supply to the analog signal
Fault in analog ground
Fault in the pulse width modulated signal cable between the engine control module (ECM) and the accelerator pedal (AP) position sensor
Defective accelerator pedal (AP) position sensor.

Fault symptom[s]

Poor accelerator pedal (AP) response
The accelerator pedal (AP) is ignored when braking.