Faulty Signal
ECM-950F ACCELERATOR PEDAL (AP) POSITION SENSOR
FAULTY SIGNAL
Checking the status
Hint: If diagnostic trouble code (DTC) ECM-9520 or ECM-9530 is stored in the engine control module (ECM), these diagnostic trouble codes (DTCs) should be fault-traced first.
- Ignition on.
Check whether the fault is permanent or intermittent. Read off the analog signal and the pulse width modulation (PWM) signal from the accelerator pedal (AP) position sensor.
Check that the difference between the signals is not more than approximately 4%. Check that the value is between 6�9% with unaffected accelerator pedal (AP) and between 85�90% with the accelerator pedal (AP) fully depressed.
Check the signals throughout the measurement range of the accelerator pedal (AP) position sensor (from completely released to completely depressed). Make the check using slow movements of the accelerator pedal (AP).
The fault is intermittent if the signals are correct.
Hint: A defective accelerator pedal (AP) position sensor is indicated if any of the returned signals deviates at a specific accelerator pedal (AP) angle.
Checking the wiring and components
Hint: If diagnostic trouble code (DTC) ECM-9520 or ECM-9530 is stored in the engine control module (ECM), these diagnostic trouble codes (DTCs) should be fault-traced first.
Check the fuse for the cable between accelerator pedal (AP) position sensor terminal #1 and system relay terminal #3 (87). If the fuse is blown, check the cable for a short-circuit to ground.
Check the accelerator pedal (AP) position sensor connector. Check for contact resistance and oxidation. In particular check terminals #1 (power supply from the system relay) and #3 (ground).
Check the voltage cable between accelerator pedal (AP) position sensor terminal #1 and system relay terminal #3 (87). Check for an open-circuit.
Hint: With the ignition on, the voltage must be approximately battery voltage between accelerator pedal (AP) position sensor terminal #1 and ground.
Check the ground lead between accelerator pedal (AP) position sensor terminal #3 and ground. Check for an open-circuit.
Hint: The resistance must be approximately 0 ohm between accelerator pedal (AP) position sensor terminal #3 and ground.
Check the signal cable (pulse width modulation (PWM) signal) between engine control module (ECM) terminal #B25 (#B35) and accelerator pedal (AP) position sensor terminal #2. Check for an open-circuit. Check for a short-circuit to supply voltage. Check for a short-circuit to ground.
Check the signal cable (analog signal) between engine control module (ECM) terminal #B17 (#B27) and accelerator pedal (AP) position sensor terminal #5. Check for an open-circuit. Check for a short-circuit to supply voltage. Check for a short-circuit to ground.
If the fault is intermittent and no fault is detected in the above fault-tracing, the fault may be because there was a delay before the system relay switched on. This delay may be due to low battery voltage and/or a mechanical fault in the system relay.
Try a new accelerator pedal (AP) position sensor if no fault is found during the above fault-tracing.
Other information
- To access/replace the system relay, Locations
- To access/replace the accelerator pedal (AP) position sensor, Accelerator Pedal Module, Replacing
- Checking Wiring and Terminals
Verification
Hint: After carrying out the repair, check that the fault has been remedied.
- Ignition off
- Reinstall the connectors, components etc.
- Ignition on
- Check the function. Read off the analog and pulse width modulated signals from the accelerator pedal (AP).
Check that the difference between the signals is not more than 4%. The value is between 6�9% when the accelerator pedal (AP) is unaffected and 85�90% when the accelerator pedal (AP) is fully depressed.
Is the function correct?
Yes - Tesing Complete.
No - Continue below.
Fault-tracing information
The fault should have been detected and remedied. As this is not the case fault-tracing has failed. Exit fault-tracing for this diagnostic trouble code (DTC) or make another attempt.