Preliminary Instructions

WARNING: This page is about a different car, the 1995 Mazda MX-6 and 1995 Mazda 626. However, it is still accessible from the selected car via links, so may be relevant.

Record and clear continuous memory codes. Warm engine to normal operating temperature. Place gear selector in Drive position. Accelerate hard to 35 MPH and coast down to a stop. Shut off engine. Perform KOEO SELF-TEST. Go to next step.

1) Continuous Memory Code 452: Verify Code Or Complaint Code 452 indicates PCM detected incorrect output signal from VSS sometime during the last 40 or 80 warm-up cycles. Possible causes for this code are:

Faulty VSS.
Open or shorted circuit.
Faulty PCM.

Perform appropriate drive cycle procedure. See PRELIMINARY INSTRUCTIONS. Ensure driveability complaint can be verified. If Code 452 is still present or driveability complaint can be verified, go to next step. If code is not present or complaint cannot be verified, fault cannot be duplicated at this time. Clear codes and see SYMPTOMS in TESTS W/O CODES article.

2) Check VSS Circuit Continuity Turn ignition off. Disconnect VSS. Disconnect PCM 60-pin connector and inspect for damaged pins, corrosion and loose wires. Repair as necessary. Install Breakout Box (49-UN01-058), leaving PCM disconnected. Measure resistance between VSS (+) terminal at VSS wiring harness connector and test pin No. 3 at breakout box. Also, measure resistance between VSS (-) terminal at VSS wiring harness connector and test pin No. 6 at breakout box. If any resistance reading is more than 5 ohms, repair open circuit in VSS wiring harness. Remove breakout box reconnect all components. Repeat step 1). If both resistance readings are 5 ohms or less, go to next step.

3) Check VSS Circuits For Shorts To Power Or Ground Turn ignition off. Disconnect VSS. With breakout box installed and PCM disconnected, measure resistance between test pin No. 3 and test pins No. 6, 37 and 40 at breakout box. If all readings are more than 500 ohms, go to next step. If any reading is 500 ohms or less, repair shorts in VSS wiring harness and repeat step 1).

4) Check VSS Resistance Turn ignition off. Disconnect VSS. Measure resistance between VSS terminals. If resistance is not 190-250 ohms, replace VSS and repeat step 1). If resistance is 190-250 ohms, replace PCM and repeat step 1).