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HOMESERVICE MANUALSFORD1999MUSTANG GT, 2D CONVERTIBLE, STANDARDREPAIR AND DIAGNOSIS (SINGLE PAGE)EXTERNAL PAGESDIFFERENT CARSECTION 2556 (ENGINE CONTROLS - PINPOINT TEST A: NO START THROUGH PINPOINT TEST DK: ACCELERATOR PEDAL POSITION (APP) SENSOR - (EXCEPT DIESEL & HYBRID))PINPOINT TEST DF: VEHICLE SPEED CIRCUIT (VSC) CHECKTEST PROCEDURE
1999 Ford Mustang GT, 2D Convertible, Standard

Test Procedure

1999 Ford Mustang GT, 2D Convertible, StandardSECTION Test Procedure
WARNING: This page does not describe the selected car, but rather 31 other vehicles, including the 2008 Mercury Sable, 2008 Mercury Mountaineer, 2008 Mercury Milan, 2008 Mercury Mariner, and 2008 Mercury Grand Marquis. However, it is still accessible from the selected car via links, so may be relevant.
  1. DF1 DTCS P0500, P0503, P1500, P1501 AND P1502: CHECK THE VEHICLE SPEED CIRCUIT FOR INTERMITTENT CONCERNS 
    NOTE: The PCM detected an error in the vehicle speed information received from the ABS control module. This test step checks for the recurrence of this vehicle speed error.
    • Key ON, engine OFF.
    • Clear the DTCs.
    • Gradually increase the vehicle speed to 80 km/h (50 mph).
    • Coast to an idle and stop the vehicle.
    • Key in OFF position.
    • Key ON, engine OFF.
    • Retrieve the continuous memory DTCs.
    • Are DTCs P0500, P0503, P1500, P1501 or P1502 present? 
    Yes No
    The vehicle speed input is incorrect.
    GO to  DF2.    		 The vehicle speed input is correct. The concern that produced the original DTC may be intermittent.
    GO to  DF5.
  2. DF2 CHECK THE VSC CIRCUIT FOR A SHORT TO VOLTAGE IN THE HARNESS 
    • Key in OFF position.
    • PCM connector disconnected.
    • Anti-lock Brake System (ABS) Module connector disconnected.
    • Key ON, engine OFF.
    • Measure the voltage between:
      ( + ) PCM Connector, Harness Side ( - )
      VSC - Pin B29 Ground
    • Is the voltage less than 1 V? 
    Yes No
    GO to  DF3. GO to  DF6.
  3. DF3 CHECK FOR AN OPEN VSC BETWEEN THE PCM AND THE ABS CONTROL MODULE 
    • Measure the resistance between:
      ( + ) PCM Connector, Harness Side ( - ) Anti-lock Brake System (ABS) Module Connector, Harness Side
      VSC - Pin B29 VSC - Pin 21
    • Is the resistance less than 5 ohms? 
    Yes No
    GO to  DF4. REPAIR the open circuit. CLEAR the DTCs. REPEAT the self-test.
    GO to  DF7.
  4. DF4 CHECK THE VSC CIRCUIT FOR A SHORT TO GROUND IN THE HARNESS 
    • Measure the resistance between:
      ( + ) PCM Connector, Harness Side ( - )
      VSC - Pin B29 Ground
    • Is the resistance greater than 10K ohms? 
    Yes No
    REFER to the VEHICLE DYNAMIC SYSTEMS articles to continue diagnosis of the ABS control module, speed sensors and wheel speed sensor harness circuits. If these components are working properly,
    GO to  DF8.    		 GO to  DF6.
  5. DF5 VISUAL INSPECTION 
    NOTE: Refer to the Wiring Diagrams article for harness, module, and connector locations.
    • Key in OFF position.
    • Visually inspect the VSC circuit harness and connectors at the PCM, ABS, and other VSC user modules for damage, loose connections, loose grounds, or incorrect routing.
    • Does the visual inspection reveal a concern? 
    Yes No
    REPAIR as necessary. CLEAR the DTCs. REPEAT the self-test.
    GO to  DF7.    		 Unable to duplicate or identify the concern at this time. REFER to the VEHICLE DYNAMIC SYSTEMS articles to continue diagnosis of the ABS control module, speed sensors and wheel speed sensor harness circuits.
  6. DF6 VERIFY IF THE VSC IS SHORTED IN THE HARNESS OR ANOTHER MODULE 
    • Key in OFF position.
    • Determine which, if any, modules are connected to the VSC. Refer to the Wiring Diagrams article. If no other modules are connected to the VSC, go to the YES Action To Take.
    • One at a time, disconnect the modules associated with the VSC. After disconnecting each module, test again for a short circuit. (Refer to test step that sent you here). Repeat until each associated module is disconnected or the short circuit is eliminated.
    • Does the short circuit remain after all associated modules are disconnected? 
    Yes No
    REPAIR the short circuit. CLEAR the DTCs. REPEAT the self-test.
    GO to  DF7.    		 REFER to the Workshop article for further diagnosis of the appropriate module.
    GO to  DF7.
  7. DF7 VSC REPAIR VERIFICATION DRIVE CYCLE 
    NOTE: Warm the engine to a normal operating temperature before continuing.
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When to See a Mechanic

Stop DIY work and contact a certified mechanic immediately if any of the following apply:

  • • You smell fuel, burning insulation, or see smoke.
  • • Brakes feel soft, pull hard to one side, or make grinding noises.
  • • The engine overheats, stalls repeatedly, or misfires under load.
  • • You are missing required tools, torque specs, or safe lifting equipment.
  • • You are not confident in the next step or safety outcome.