Test K - Vehicle Speed Sensor
Be aware that the following pinpoint test is to be used only when codes 27, or 29 are received in QUICK TEST .
- Drive Cycle for Checking VSS. For automatic transmission equipped vehicles: record and clear EEC-IV SELF-TEST continuous codes. Warm engine to operating temperature. When in first gear accelerate moderately to 25 MPH and coast down to idle and stop. Shut off engine. Perform KEY OFF/ENGINE OFF test. Verify if code 29 is present. For manual transmission equipped vehicles: record and clear EEC-IV SELF-TEST continuous codes. Warm engine to operating temperature. Starting in first gear, shift to second gear and accelerate moderately to 40 MPH. Coast down to idle and stop. Shut off engine. Perform KEY OFF/ENGINE OFF SELF TEST. Verify if code 29 is present. If any other codes are present, return to QUICK TEST . If codes are not present, test is completed. If code 29 is present, go to next step.
- Sensor Check. Turn key off, wait 10 seconds. Disconnect vehicle speed sensor. Set DVOM on 200,000-ohm scale. Measure resistance across vehicle speed sensor. If resistance is not between 190-230 ohms, replace VSS sensor and repeat step 1). If resistance is between 190 and 230 ohms, go to next step.
- Turn key off, wait 10 seconds. Remove ECA pin connector and inspect for damaged pins, corrosion, or loose wires. Repair and replace as necessary. Install breakout box. With ECA and VSS disconnected, set DVOM on 200-ohm scale. Measure resistance between test pin No. 3 at breakout box and VSS at vehicle harness. Measure resistance between test pin No. 6 at breakout box and VSS vehicle harness connector. If both resistances are 5 ohms or more, service open circuit in VSS harness and repeat test K, step 1). If resistance is 5 ohms or less, go to next step.
- Turn key off and disconnect ECA. Set DVOM on 200,000-ohm scale. Measure resistance between pin No. 3 and pins No. 37, 40 and 6 at breakout box. Then measure resistance between pin No. 6 and pins No. 37 and 40 at breakout box. If readings are less than 10,000 ohms repair shorts and repeat step 1). If readings are greater than 10,000 ohms, go to next step.
- Substitute VSS with known good sensor. Connect ECA and VSS. Repeat step 1), then return to this step. If code 29 is present, replace ECA and repeat step 1). If no codes are present, the original code 29 was result of faulty original VSS malfunction. Service VSS as necessary.