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Home >> Volvo >> 2000 >> S70 GLT SE >> Repair and Diagnosis >> Engine Performance >> System >> Engine Controls - Self-Diagnostics - Turbo >> Diagnostic Tests >> P1520/ECM-9180: Accelerator Pedal Position Sensor >> Diagnostic Procedure

Diagnostic Procedure

NOTE: If no fault is found in wiring between ECM and throttle unit, fault can be due to a defective accelerator pedal position sensor, defective electronic throttle module or defective ECM. Signal from throttle unit terminal No. 2 is a pulse width modulated voltage of approximately battery voltage and has a frequency of approximately 200 Hz.
  1. Check that connector terminals for accelerator pedal position sensor are OK. See CHECKING WIRING & CONNECTIONS  or COMPONENT LOCATIONS .
  2. Check that there is voltage to accelerator pedal position sensor from fuse located in relay/fuse box attached to left strut tower just behind air cleaner housing. See ENGINE PERFORMANCE WIRING DIAGRAMS article.
  3. Check DTC status to see if fault is intermittent or permanent. Connect a scan tool and start engine. Hold down brake pedal and press accelerator pedal down simultaneously. Fault is intermittent if RPM increases. Fault is permanent if RPM does not increase. Go to next step.
    NOTE: Switch off the engine. Repeat the start procedure three times (to attempt to induce a permanent fault).
  4. Read out DTCs in fault memory. If DTCs such as ECM-9520, ECM-958F, ECM-959F or ECM-917F are stored, wiring between accelerator pedal position sensor and ECM is faulty or accelerator pedal position sensor is defective. If any of these other DTCs are present, go to step  5. If none of these other DTCs are present, go to step  8.
  5. Connect breakout box. See CONNECTING & DISCONNECTING BREAKOUT BOX . Go to next step.
  6. Check cable between ECM terminal B25 (breakout box terminal B35) and accelerator pedal position sensor terminal No. 2 for an open circuit, short to supply voltage and a short to ground. See Figure. Repair as necessary and go to next step.
  7. Disconnect breakout box when wiring repair is complete. See CONNECTING & DISCONNECTING BREAKOUT BOX . Verify repair. Turn ignition OFF. Ensure connectors and components are installed correctly. Read out pulse modulated signal. Depress and release accelerator pedal. Value is approximately 7% when accelerator pedal is released and approximately 85% when accelerator pedal is fully depressed. If value correct, repair is complete. If fault remains, go to step  11.
  8. Connect breakout box. See CONNECTING & DISCONNECTING BREAKOUT BOX . Go to next step.
  9. Check cable between ECM terminal A56 and accelerator pedal position sensor terminal No. 1 for an open circuit, short to supply voltage and a short to ground. See Figure. Repair as necessary and go to next step.
  10. Disconnect breakout box when wiring repair is complete. See CONNECTING & DISCONNECTING BREAKOUT BOX . Verify repair. Ignition OFF. Ensure connectors and components are installed correctly. Read out pulse modulated signal. Depress and release accelerator pedal. Value is approximately 7% when accelerator pedal is unaffected and approximately 85% when accelerator pedal is fully depressed. If value correct, repair is complete. If fault remains, go to next step.
  11. Replace accelerator pedal position sensor with a known good unit. See REMOVAL, OVERHAUL & INSTALLATION - EXCEPT S40 & V40 article. Verify repair. Ignition OFF. Ensure connectors and components are installed correctly. Read out pulse modulated signal. Depress and release accelerator pedal. Value is approximately 7% when accelerator pedal is unaffected and approximately 85% when accelerator pedal is fully depressed. If value correct, repair is complete. If fault remains, go to next step.
  12. Replace electronic throttle module with a known good unit. See REMOVAL, OVERHAUL & INSTALLATION - EXCEPT S40 & V40 article. Verify repair. Ignition OFF. Ensure connectors and components are installed correctly. Read out pulse modulated signal. Depress and release accelerator pedal. Value is approximately 7% when accelerator pedal is unaffected and approximately 85% when accelerator pedal is fully depressed. If value correct, repair is complete. If fault remains, go to next step.
    NOTE: A new Electronic Throttle Module (ETM) is delivered without software. For the ETM to function after replacement, it must be programmed using Volvo factory scan tool, or equivalent aftermarket scan tool.
  13. Replace ECM with a known good unit. See REMOVAL, OVERHAUL & INSTALLATION - EXCEPT S40 & V40 article. Verify repair. Ignition OFF. Ensure connectors and components are installed correctly. Read out pulse modulated signal. Depress and release accelerator pedal. Value is approximately 7% when accelerator pedal is unaffected and approximately 85% when accelerator pedal is fully depressed. If value correct, repair is complete.
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