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DTC P1501: VEHICLE SPEED SENSOR (VSS) Mazda 626 GF

Testing & Diagnostics ~318 words
  1. Check PCM VSS PID For Input Signal Ensure freeze frame data is recorded. DTC indicates VSS input signal is out of range. A DTC 1501 will be set and self-test will abort whenever PCM detects VSS input signal during KOER self-test. Possible causes for this code are: Noisy VSS input signal from RFI/EMI external source (ignition wires, charging circuits etc.). Turn ignition off. Connect scan tool to DLC. Start engine and allow to idle. Using scan tool, access VSS PID and observe vehicle speed input to PCM. While observing VSS PID, increase engine speed to 2000 RPM and decrease to idle several times. If VSS PID reading is less than 3 MPH, fault cannot be duplicated at this time. Testing is complete. If VSS PID reading is 3 MPH or more, go to next step.
  2. Visually Inspect VSS Wiring Harness Ensure wiring is not routed near ignition wires or generator wires. Verify VSS wiring harness is shielded and grounded (if applicable). Repeat step 1 to verify circuit continuity. If faults are found, repair or replace as necessary. Clear PCM memory and go to next step. If no faults are found, fault cannot be duplicated at this time. Testing is complete.
  3. VSS Drive Cycle Record and clear continuous memory codes. Warm engine to normal operating temperature. Perform appropriate drive cycle as follows: On models with A/T, place gear selector in Drive. Accelerate hard to 35 MPH and coast down to a stop. Repeat procedure 3 times. Shut off engine. Repeat «QUICK TEST»(ref-91102-S14663847332001030200000) . Service codes as necessary. If no codes are present, testing is complete. On models with M/T, start in first gear, shifting no higher than second gear. Accelerate moderately to 40 MPH. Coast down to idle, and stop. Repeat procedure 3 times. Shut engine off. Repeat «QUICK TEST»(ref-91102-S14663847332001030200000) . Service codes as necessary. If no codes are present, testing is complete.

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