Test DL: Vehicle Speed Sensor: Testing

WARNING: This page does not describe the selected car, but rather 10 other vehicles, including the 2002 Ford RV Cutaway, 2002 Ford Pickup, 2002 Ford F550 Super Duty, 2002 Ford F450 Super Duty, and 2002 Ford Excursion. However, it is still accessible from the selected car via links, so may be relevant.

NOTE: For additional testing information, see DIAGNOSTIC AIDS .

NOTE: Delayed engagement or no vehicle movement may be caused by a transmission concern. Harsh shifts and/or erratic speedometer may be caused by a failed speedometer or an open or intermittent ground within instrument panel on vehicles with electronic readout.

1) Continuous Memory DTC P0500: Check Continuity Of VSS Circuits
DTC P0500 indicates PCM detected a VSS circuit failure. Possible causes are:
- Open In VSS (+) Or VSS (-) Circuits
- Short To Ground Or SIG RTN In VSS (+) Or VSS (-) Circuits
- Short To PWR In VSS (+) Or VSS (-) Circuits
- Faulty VSS
- Faulty PCM
Turn ignition off. Disconnect PCM connector and inspect for damaged pins, corrosion and loose wires. PCM is located in left rear of engine compartment, near brake master cylinder. Repair connector as necessary. Install Rotunda Breakout Box (014-00950), leaving PCM disconnected. Disconnect VSS connector located on left side of transmission extension housing. Using DVOM, measure resistance of VSS (+) circuit (Gray/Black wire) between VSS harness connector and test pin No. 58 at breakout box. Using DVOM, measure resistance of VSS (-) circuit (Pink/Orange wire) between VSS harness connector and test pin No. 33 at breakout box. If both resistances are less than 5 ohms, go to next step. If either resistance is 5 ohms or more, repair open in appropriate wire between VSS and PCM. Clear DTCs and retest.

2) Check VSS Circuits For Short To Ground, SIG RTN & Power

Ensure ignition is off. Using DVOM, measure resistance between the following test pins at breakout box:
- Test pin No. 58 and test pins No. 51, 76, 77 and 103 (PWR GND) at breakout box.
- Test pin No. 58 and test pin No. 33 (VSS-) at breakout box.
- Test pin No. 58 and test pin No. 91 (SIG RTN) at breakout box.
- Test pin No. 58 and test pin No. 71 (VPWR) at breakout box.
- Test pin No. 33 and test pin No. 71 (VPWR) at breakout box.
If all resistances are more than 500 ohms, go to next step. If any resistance is 500 ohms or less, repair short circuit as necessary. See WIRING DIAGRAMS article. Restore vehicle. Clear DTCs and retest.

3) Check VSS Resistance

Ensure ignition is off. Using DVOM, measure resistance between VSS terminals. If resistance is not 190-250 ohms, replace VSS. Restore vehicle. Clear DTCs and retest. If resistance is 190-250 ohms, replace PCM. Restore vehicle. Clear DTCs and retest.
NOTE: A break in step numbering sequence occurs at this point. Procedure skips from step 3) to step 10). No test procedures have been omitted.

NOTE: For additional testing information, see DIAGNOSTIC AIDS .

NOTE: If PCM detects a VSS input signal any time during KOER ON DEMAND SELF-TEST, DTC P1501 will be set and testing will abort.

10) KOER DTC P1501: Check PCM VSS PID For Input Signal
DTC P1501 is set when PCM detects VSS input signal is out of self-test range during KOER ON-DEMAND SELF-TEST. Possible causes for this fault are:
- Noisy VSS input signal from Radio Frequency Interference (RFI).
- Noisy VSS input signal from Electromagnetic Interference (EMI) external source (ignition wires, charging circuits, etc.).
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 value is 3 MPH or more, go to step 13). If VSS PID value is less than 3 MPH, fault cannot be duplicated at this time. Clear DTCs and retest.

NOTE: For additional testing information, see DIAGNOSTIC AIDS .

11) Continuous Memory DTC P0503: Check VSS & VSS Circuit For Intermittent Fault
DTC P0503 indicates poor or noisy VSS performance. Possible causes for this fault are:
- Noisy VSS input signal from Radio Frequency Interference (RFI).
- Noisy VSS input signal from Electromagnetic Interference (EMI) external source (ignition wires, charging circuits, etc.).
- Faulty VSS Or Driven Gears
- Faulty Wiring Harness Or Connectors
Turn ignition switch to OFF position. Disconnect VSS connector located on left side of transmission extension housing. 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 any faults are found, repair as necessary. If no faults are found, go to next step.

12) Check PCM VSS PID For Input Signal

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 speed, check for VSS PID variations of plus or minus 5 MPH for 10 seconds or more. If any variations occur, go to next step. If no such variations occur, fault cannot be duplicated at this time. DTC P0503 may have been set from sources external of vehicle. Service any other DTCs. Clear DTCs and retest.

13) Check VSS Wiring Harness Routing

Visually inspect VSS wiring harness. Ensure wiring is not routed near high current wires (ignition wiring or alternator wiring). Verify VSS wiring harness is shielded and grounded (if applicable). Go to step 1) to check VSS circuit continuity. If any faults are found, service as necessary. Clear DTCs and retest. If no faults are found, fault cannot be duplicated at this time. Repeat QUICK TEST .