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P1596: Speed Control Switch Always High: Testing

  1. Engine Running. With the DRBIII®, read DTCs and record the related Freeze Frame data. With the DRBIII® in Sensors, read the Speed Control inputs state. While monitoring the DRBIII®, push the Speed Control On/Off Switch several times, then leave it on. Did the DRBIII® show Speed Control Switching off and on? If yes, refer to the INTERMITTENT CONDITION  under SELF-DIAGNOSTIC SYSTEM. If no, go to the next step.
  2. Turn the ignition off. Disconnect the S/C On/Off Switch 2-way harness connector only. Measure the resistance across the S/C On/Off Switch. Is the resistance between 20.3-20.7 k/ohms? If yes, go to the next step. If no, replace the On/Off Switch.
  3. Disconnect the upper and lower 6-way clockspring harness connectors. Measure the resistance of the (K4) Sensor ground circuit between the upper and lower 6-way clockspring harness connectors. Measure the resistance of the (V37) S/C Switch Signal circuit between the upper and lower 6-way clockspring harness connectors. Was the resistance above 5.0 ohms for either circuit? If yes, replace the clockspring. If no, go to the next step.
  4. Connect the Clockspring harness connectors. Disconnect the Speed Control On/Off Switch 2-way harness connector only. Ignition on, engine not running. Measure the voltage on the (V37) S/C Switch Signal circuit in the On/Off Switch 2-way connector. Is the voltage above 5.2 volts? If yes, repair the short to voltage in the (V37) S/C Switch Signal circuit. If no, go to the next step.
  5. Turn the ignition off. Disconnect the lower Clockspring 6-way harness connector. Disconnect the PCM harness connectors. Measure the resistance of the (V37) S/C Switch Signal circuit from the PCM harness connector to the lower Clockspring harness connector. Is the resistance below 5.0 ohms? If yes, go to the next step. If no, repair the open in the (V37) S/C Switch Signal circuit between the PCM and Clockspring.
  6. Measure the resistance of the (K4) Sensor ground circuit from the PCM harness connector to the lower Clockspring harness connector. Is the resistance below 5.0 ohms? If yes, go to the next step. If no, repair the open (K4) Sensor ground circuit between the PCM and Clockspring.
  7. Disconnect the upper clockspring harness connector. Measure the resistance of the (V37) S/C Switch Signal circuit from the upper Clockspring harness connector to the On/Off switch harness connector. Is the resistance below 5.0 ohms? If yes, go to the next step. If no, repair the open in the (V37) S/C Switch Signal circuit, Clockspring to S/C Switch.
  8. Measure the resistance of the (K4) Sensor ground circuit from the On/Off Switch 2-way harness connector to the upper Clockspring harness connector. Is the resistance below 5.0 ohms? If yes, go to the next step. If no, repair the open in the (K4) Sensor ground circuit between the Clockspring and S/C Switch.
    9. NOTE: Before continuing, check the PCM harness connector terminals for corrosion, damage, or terminal push out. Repair as necessary.
  9. Using the wiring diagram as a guide, inspect the wire harness and connectors. Pay particular attention to all power and ground circuits. If the there are no possible causes remaining, replace the Powertrain Control Module. Program the new PCM. See PROGRAMMING .
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