Sveriges Volvoforum

ECM-950F

#Condition
Engine control module (ECM) receives information about the accelerator pedal's position via the accelerator pedal position sensor's two internal position sensors, where one generates an analogue signal and the other a pulse-width modulated signal (PWM). If Engine control module (ECM) registers that there is a difference of more than 5 % between the two sensors' signals for longer time than 0.4 seconds, then diagnostic trouble code ECM-950F, Faulty signal, is stored. At times when the analogue signal is in the process of changing, e.g., during acceleration, a greater deviation between both signals is allowed.

For model years 1999-2001, an engine speed higher than 700 rpm is required for the test to be active. For model year 2002-, the test is active when the ignition is on.
For upgraded software, released during year 2006 or later, the above detection time is increased from 0.4 to 0.7 seconds.


#Substitute value
Slow opening of throttle.
The throttle opens slower than during normal requested open because the system is regulated by only one of the pulse width modulated signals from the accelerator pedal position sensor. The driver may notice that the engine responds a bit slower compared to normal throttle application.
Closing of throttle during braking.
The accelerator pedal position is ignored when the brake pedal is depressed.

#Possible source
Loose connections or contact resistance in the terminals on the analogue signal cable
Open-circuit in the power supply for the accelerator pedal (AP) position sensor
Open-circuit in the ground lead for the accelerator pedal (AP) position sensor
Fault in the PWM signal between the engine control module (ECM) and the electronic throttle module (ETM)
Defective system relay
Defective accelerator pedal (AP) position sensor.

#Fault symptom[s]
Poor accelerator pedal (AP) response.


ECM-9520

#Condition
The accelerator pedal position sensor has two different internal sensors, where one generates an analogue signal and the other a pulse-width modulated (PWM) signal.
If Engine control module (ECM) detects any of the following faults on the pulse-width modulated (PWM) signal which comes from the accelerator pedal position sensor:
The frequency is lower than 100 Hz or higher than 300 Hz for longer time than 0.3 seconds, then diagnostic trouble code ECM-9520, Signal missing, is generated.
The pulse ratio is lower than 3 % for longer time than 0.3 seconds, then diagnostic trouble code ECM-9520, Signal missing, is generated.
The pulse ratio is higher than 97% for longer time than 0.3 seconds, then diagnostic trouble code ECM-9520, Faulty signal, is generated.

For model years 1999-2001, an engine speed higher than 700 rpm is required for the test to be active.
For model year 2002-, the test is active when the ignition is on.
For upgraded software, released during year 2006 or later, the above detection times are increased from 0.3 to 0.7 seconds.

#Substitute value
Slow opening of throttle.
The throttle opens slower than during normal requested open because the system is regulated by only one of the pulse width modulated signals from the accelerator pedal position sensor. The driver may notice that the engine responds a bit slower compared to normal throttle application.
Closing of throttle during braking.
The accelerator pedal position is ignored when the brake pedal is depressed.

#Possible source
Signal too high:
Damaged accelerator pedal (AP) position sensor.
Loose connections in leads.

Signal missing:
Open circuit on signal cable.
Loose connections or contact resistance in the terminals on the pulse width modulation (PWM) signal cable.
Damaged accelerator pedal (AP) position sensor.
Short-circuit to supply voltage in the signal cable.

Faulty signal:
The signal cable is short-circuited to ground.
Damaged accelerator pedal (AP) position sensor.

#Fault symptom[s]
the accelerator pedal (AP) is ignored when braking
slow response during acceleration
the ETS warning lamp lights (C70 and S/V70 -2000 only).