Preliminary Instructions (M/T)

Record and clear continuous memory codes. Warm engine to normal operating temperature. Accelerate moderately to 40 MPH. Start in first gear, shifting no higher than second gear. Coast down to idle, and stop. Shut off engine. Perform KOEO SELF-TEST, and record continuous memory codes. Go to step 1).

1) Continuous Memory Code 452  Code 452 indicates PCM detected incorrect output from VSS sometime during vehicle operation. Possible causes for this code are:

• Faulty VSS.
• Open or shorted circuit.
• Faulty PCM.

Perform appropriate drive cycle procedure. See PRELIMINARY INSTRUCTIONS (A/T) or PRELIMINARY INSTRUCTIONS (M/T) headings above. 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, the fault cannot be duplicated at this time. Clear codes, and refer to SYMPTOMS in the TESTS W/O CODES article in this section.

2) Check VSS Circuit Continuity  Turn ignition off. Disconnect VSS sensor. Remove PCM 60-pin connector. Inspect terminals, and repair if damaged. Install EEC-IV Breakout Box (T83L-50-EEC-IV). Measure resistance between VSS (+) terminal at VSS wiring harness connector and test pin No. 3 at breakout box. 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, service open circuit in VSS wiring harness and 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. Ensure PCM and VSS are 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 less than 500 ohms, repair short in VSS wiring harness and repeat step 1).

4) Check VSS Resistance  Leave ignition off. Disconnect VSS wiring harness connector. Measure resistance across VSS terminals. If reading is not 190-250 ohms, replace VSS and repeat step 1). If resistance is 190-250 ohms, replace PCM and repeat step 1).