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Test DP: Vehicle Speed Sensor/Transfer Case Speed Sensor: Testing

    NOTE: For additional testing information, see DIAGNOSTIC AIDS .

  1. 1) Continuous Memory DTC P0500, P0501 Or P1502: Check VSS Circuits For Open In Harness (VRS Type)
    DTCs P0500, P0501 and P1502 indicate that PCM has detected an error in vehicle speed information received from Vehicle Speed Sensor (VSS), Transfer Case Speed Sensor (TCSS) or Anti-Lock Brake System (ABS) module. See VEHICLE SPEED CIRCUIT MODULE IDENTIFICATION  table. Possible causes for this fault are:
    • Open or short in VSS (+) or VSS (-) circuit.
    • Open in TCSS signal or TCSS signal return circuit.
    • Short to GND in VSS or TCSS circuit.
    • Short to PWR in VSS or TCSS circuit.
    • Open or short in VSC between PCM and appropriate control module.
    • Faulty wheel speed sensor(s).
    • Faulty wheel speed sensor(s) wiring harness.
    • Faulty module(s) connected to vehicle speed circuit.
    • Faulty transfer case, vehicle or wheel speed sensors.
    • Faulty drive mechanism for VSS or TCSS.

    Turn ignition switch to OFF position. Disconnect VSS connector. Disconnect PCM connector. Inspect connectors for loose, damaged or corroded terminals. Repair as necessary. Using a DVOM, measure resistance of VSS(+) and VSS (-) circuits between PCM harness connector and VSS harness connector. See Figure and Figure . If both resistance measurements are less than 5 ohms, go to next step. If either resistance measurement is 5 ohms or more, repair open in affected VSS(+) or (-) circuit.

  2. 2) Check VSS Circuits For Shorts To Ground Or Power In Harness

    Using a DVOM, measure resistance between VSS(+) circuit, and PWR GND, VPWR and VSS(-) circuits at PCM harness connector. See WIRING DIAGRAMS article. See Figure and Figure . If all resistance measurements are more than 5 ohms, go to next step. If any resistance measurement is 5 ohms or less, go to step  12).

  3. 3) Check VSS Resistance

    Using a DVOM, measure resistance between VSS terminals. If resistance is not 170-270 ohms, replace VSS. If resistance is 170-270 ohms, replace PCM.
    NOTE: A break in step numbering sequence occurs at this point. Procedure skips from step 3) to step 5). No test procedures have been omitted.
    4. NOTE: For additional testing information, see DIAGNOSTIC AIDS .
    Fig 1: Identifying VSS Circuits & Connector Terminals (Cougar - 2.0L M/T)
    G00013257Courtesy of FORD MOTOR CO.
    Fig 2: Identifying VSS Circuits & Connector Terminals (Cougar - 2.5L M/T)
    G99I02102Courtesy of FORD MOTOR CO.

  4. 5) Continuous Memory DTC P0500, P0501 Or P1502: Check VSS Signal Output To PCM (Hall Type)
    DTCs P0500, P0501 and P1502 indicate that PCM has detected an error in vehicle speed information received from Vehicle Speed Sensor (VSS), Transfer Case Speed Sensor (TCSS) or Anti-Lock Brake System (ABS) module. See VEHICLE SPEED CIRCUIT MODULE IDENTIFICATION  table. Possible causes for this fault are:
    • Open or short in VSS (+) or VSS (-) circuit.
    • Open in TCSS signal or TCSS signal return circuit.
    • Short to GND in VSS or TCSS circuit.
    • Short to PWR in VSS or TCSS circuit.
    • Open or short in VSC between PCM and appropriate control module.
    • Faulty wheel speed sensor(s).
    • Faulty wheel speed sensor(s) wiring harness.
    • Faulty module(s) connected to vehicle speed circuit.
    • Faulty transfer case, vehicle or wheel speed sensors.
    • Faulty drive mechanism for VSS or TCSS.

    Turn ignition switch to OFF position. Disconnect PCM connector. Inspect connector for loose, damaged or corroded terminals. Repair as necessary. Raise and support front of vehicle (to allow rotation of front drive wheel). Opposite front wheel must be held stationary. Turn ignition switch to ON position. Using a DVOM, measure voltage between VSS and PWR GND circuits at PCM harness connector while slowly rotating drive wheel. See Figure, and Fig 1 or Fig 2 . Several cycles should be observed of voltage rising to more than 5 volts and then falling to less than one volt in a regular cycle as drive wheel is rotated. If voltage cycles as specified, replace PCM. If voltage does not cycle as specified, go to next step.

  5. 6) Check Voltage Between VPWR & PWR GND Circuits At VSS

    Turn ignition switch to OFF position. Disconnect VSS connector. Turn ignition switch to ON position. Using a DVOM, measure voltage between VPWR and PWR GND circuits at VSS harness connector. See Fig 1 or Fig 2 . If voltage is more than 10.5 volts, go to next step. If voltage is 10.5 volts or less, go to step  10).

  6. 7) Check VSS Circuit For Short To Power In Harness

    Turn ignition switch to ON position. Using a DVOM, measure voltage between VSS(+) and PWR GND circuits at PCM harness connector. See Figure, and Fig 1 or Fig 2 . If voltage is less than one volt, go to next step. If voltage is one volt or more, go to step  12).

  7. 8) Check VSS Circuit For Short To Ground In Harness

    Turn ignition switch to OFF position. Using a DVOM, measure resistance between VSS(+) and PWR GND circuits at PCM harness connector. If resistance is more than 3000 ohms, go to next step. If resistance is 3000 ohms or less, go to step  12).

  8. 9) Check VSS Signal Circuit For Open In Harness

    Using a DVOM, measure resistance of VSS(+) circuit between PCM harness connector and VSS harness connector. If resistance is less than 5 ohms, replace VSS. If resistance is 5 ohms or more, repair open in VSS(+) circuit.

  9. 10) Check VSS Ground Circuit For Open In Harness

    Turn ignition switch to OFF position. Ensure PCM and VSS are disconnected. Using a DVOM, measure resistance of PWR GND circuit between chassis ground and VSS harness connector. See Fig 1 or Fig 2 . If resistance is less than 5 ohms, repair open in VPWR circuit to VSS. If resistance is 5 ohms or more, repair open in VSS PWR GND circuit.
    NOTE: A break in step numbering sequence occurs at this point. Procedure skips from step 10) to step 12). No test procedures have been omitted.

  10. 12) Verify If VSS Circuit Is Shorted In Wiring Harness Or Another Module

    Determine if any other modules are connected to VSS circuit. See WIRING DIAGRAMS article. If no other modules are connected to vehicle speed circuit, repair short in PWR GND, VPWR or VSS(-) circuit. If other modules are connected to vehicle speed circuit, disconnect each module that is associated with VSS circuit (one at a time). After disconnecting each module, check again for short circuit. Perform diagnostics in test step that directed you to this step. Repeat until each associated module has been disconnected or until short circuit has been eliminated. If short circuit no longer exists with associated module(s) disconnected, diagnose appropriate module and/or related system. See appropriate MODULE COMMUNICATIONS NETWORK article in ACCESSORIES & EQUIPMENT. If short circuit still exists with all associated modules disconnected, repair short in VSS circuit.
    NOTE: A break in step numbering sequence occurs at this point. Procedure skips from step 12) to step 15). No test procedures have been omitted.
    11. NOTE: For additional testing information, see DIAGNOSTIC AIDS .
    NOTE: A break in step numbering sequence occurs at this point. Procedure skips from step 15) to step 20). No test procedures have been omitted.

  11. 15) KOER DTC P1501: Check PCM VSS PID For Input Signal
    This DTC indicates VSS input signal was detected by PCM during self-test. A DTC P1501 will be stored and self-test will abort when this occurs. Noisy VSS input signal from Radio Frequency Interference (RFI) or Electromagnetic Interference (EMI) external source (i.e.; ignition wires, charging circuits, etc.) can be possible causes for this fault.

    Connect scan tool to Data Link Connector (DLC). Start engine and allow to idle. Using scan tool, access VSS PID from PID/DATA MONITOR & RECORD menu and observe vehicle speed input to PCM. While observing VSS PID, increase engine speed to 2000 RPM and return to idle several times. If VSS PID reading is 3 MPH or more, go to step  22). If VSS PID value is less than 3 MPH, fault cannot be duplicated at this time. Clear DTCs and repeat QUICK TEST . If DTC P1501 is still present, go to TEST Z, step 1) .

    12. NOTE: For additional testing information, see DIAGNOSTIC AIDS .

  12. 20) Continuous Memory DTC P0503: Check For Intermittent Fault
    This DTC indicates poor or noisy VSS performance. Possible causes for this fault are:
    • Noisy TCSS/VSS Input Signal From Radio Frequency Interference (RFI) or Electromagnetic Interference (EMI) (Ignition Wires, Charging Circuits, Etc.)
    • Faulty VSS Or Driven Gears
    • Faulty TCSS
    • Damaged Wiring Harness Or Connectors
    • Faulty Module Or Circuit Connected To TCSS/VSS
    • Aftermarket Add-On Accessories

    Turn ignition switch to OFF position. Disconnect VSS sensor. Visually inspect VSS and VSS circuits for potential faults as follows:

    • Loose VSS Circuit Connectors
    • Loose VSS Circuit Connector Terminals
    • Damaged VSS Wiring Harness Insulation
    • Incorrect VSS Circuit Routing
    • Incorrect VSS Installation

    If no faults are found, go to next step. If faults are found, repair as necessary.

  13. 21) Check PCM VSS PID For Input Signal

    Turn ignition switch to OFF position. Connect scan tool to Data Link Connector (DLC). Using scan tool, access VSS PID from PID/DATA MONITOR & RECORD menu. Test drive vehicle at several steady speeds at more than, and less than 30 MPH.
    NOTE: On scan tools with Data Record feature, record data for playback to help identify variations.

    During each steady state speed, check for VSS PID variations of plus or minus 5 MPH for more than 10 seconds. If any variations occur, go to next step. If variations do not occur, fault cannot be duplicated at this time. Testing is complete.

  14. 22) Check VSS Harness Routing

    Visually inspect VSS wiring harness. Ensure wiring is not routed near high current wires such as ignition wires or charging system wires. Verify VSS wiring harness is shielded and grounded (if applicable). Check VSS wiring harness resistance. Refer to Figure-Fig 4 to check VSS circuits. If faults are found, repair as necessary. If no faults are found, fault cannot be duplicated at this time. Go to TEST Z, step 1) and check for intermittents.
    NOTE: A break in step numbering sequence occurs at this point. Procedure skips from step 22) to step 25). No test procedures have been omitted.
    15. NOTE: For additional testing information, see DIAGNOSTIC AIDS .
    NOTE: A break in step numbering sequence occurs at this point. Procedure skips from step 25) to step 30). No test procedures have been omitted.

  15. 25) Continuous Memory DTC P1500: Visual Inspection
    This DTC indicates VSS input signal was intermittent. This DTC will be stored when a VSS fault interferes with other OBD-II tests, such as Catalyst Efficiency Monitor, EVAP Monitor, HO2S Monitor, etc. Possible causes for this fault are:
    • Intermittent Open Or Shorted Circuit
    • Faulty VSS
    • Faulty PCM

    Turn ignition switch to OFF position. Disconnect VSS sensor. Visually inspect VSS and VSS circuits for potential faults as follows:

    • Loose VSS Circuit Connectors
    • Loose VSS Circuit Connector Terminals
    • Damaged VSS Wiring Harness Insulation
    • Incorrect VSS Circuit Routing
    • Incorrect VSS Installation

    If no faults are found, go to TEST Z, step 1) . If faults are found, repair as necessary.

    16. NOTE: For additional testing information, see DIAGNOSTIC AIDS .

  16. 30) Continuous Memory DTC P0500 Or P1502: Visual Inspection
    Transfer Case Speed Sensor (TCSS) provides rotational speed of transfer case output shaft. PCM uses this signal to control powertrain behavior and on some models is used as source of vehicle speed information. Disconnect TCSS connector, located on left rear of transmission. Inspect connector for loose, damaged or corroded terminals. Repair as necessary. If connector terminals are okay, go to next step.

  17. 31) Check Resistance Of TCSS

    Using a DVOM, measure resistance between TCSS SIG and TCSS SIG RTN circuits at TCSS connector. See Fig 3 or Fig 4 . If resistance is 1000-1250 ohms, go to next step. If resistance is not 1000-1250 ohms, replace TCSS.
    Fig 3: Identifying TCSS Circuits & Connector Terminals (Pickup 4.2L 4WD With Manual Shift-On-The-Fly)
    G99C02104Courtesy of FORD MOTOR CO.
    Fig 4: Identifying TCSS Circuits & Connector Terminals (Pickup 4.6/5.4L 4WD With Manual Shift-On-The-Fly)
    G00035654Courtesy of FORD MOTOR CO.

  18. 32) TCSS Output Check

    Road test vehicle and measure frequency between TCSS SIG and TCSS SIG RTN circuits at TCSS connector. Drive vehicle between zero and 30 MPH. Compare TCSS frequency to the frequency listed in appropriate PIN VOLTAGE/PID VALUE - INPUTS table in PIN VOLTAGE/PID VALUE CHARTS - TRUCKS article. Ensure frequency increases and decreases with vehicle speed. If frequency is as specified, go to next step. If frequency is not as specified, remove TCSS from transfer case. Inspect TCSS target wheel and repair as necessary. If TCSS target wheel is okay, replace TCSS.

  19. 33) Check Harness For Short To VPWR

    Turn ignition switch to ON position. Disconnect TCSS connector. Using a DVOM, measure voltage between chassis ground and TCSS SIG circuit at TCSS harness connector. See Fig 3 or Fig 4 . If voltage is less than one volt, go to next step. If voltage is one volt or more, repair short to VPWR.

  20. 34) Check Harness For Open

    Turn ignition switch to OFF position. Disconnect PCM connector. Using a DVOM, measure resistance of TCSS SIG and TCSS SIG RTN circuits between TCSS harness connector and PCM harness connector. See Fig 3 or Fig 4 . If both resistance measurements are less than 5 ohms, go to next step. If either resistance measurement is 5 ohms or more, repair open in affected circuit.

  21. 35) Check Harness For Short To Ground

    Using a DVOM, measure resistance between TCSS SIG circuit, TCSS SIG RTN circuit and chassis ground at TCSS harness connector. See Fig 3 or Fig 4 . If both resistance measurements are more than 10 k/ohms, replace PCM. If either resistance measurement is 10 k/ohms or less, repair short to ground in TCSS SIG circuit.
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