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P1597: Speed Control Switch Always Low: Testing

  1. With the ignition on and the engine not running, read the DTCs and the S/C Switch volts status with the DRBIII®. Is the S/C Switch voltage below 1.0 volt? If yes, go to the next step. If no, refer to the INTERMITTENT CONDITION  under SELF-DIAGNOSTIC SYSTEM.
  2. Turn the ignition off and disconnect the S/C ON/OFF Switch harness connector. Turn ignition on, engine not running. With the DRBIII® in Sensors, read the S/C Switch volts. Did the S/C Switch volts change to 5.0 volts? If yes, replace the S/C ON/OFF Switch. If no, go to the next step.
  3. Turn the ignition off. Disconnect the S/C RESUME/ACCEL Switch harness connector. Turn the ignition on, engine not running. With the DRBIII® in Sensors, read the S/C Switch volts. Did the S/C Switch volts go above 4.0 volts? If yes, replace the Resume/Accel Switch. If no, go to the next step.
  4. Turn the ignition off. Disconnect the clockspring 6-way harness connector (instrument panel wiring side). Turn the ignition on, engine not running. With the DRBIII® in Sensors, read the S/C Switch voltage. Did the S/C Switch volt change to 5.0 volts? If yes, replace the clockspring. If no, go to the next step.
  5. Turn the ignition off. Connect the Clockspring harness connectors. Disconnect the PCM harness connectors. Measure the resistance between the (V37) S/C Switch Signal circuit and ground at S/C ON/OFF Switch harness connector. Is the resistance below 100 ohms? If yes, repair the short to ground in the (V37) S/C Switch Signal circuit. If no, go to the next step.
  6. Measure the resistance between the (V37) S/C Signal circuit and the (K4) Sensor ground circuit at the ON/OFF Switch harness connector. Is the resistance below 5.0 ohms? If yes, repair the short between the (K4) Sensor ground and the (V37) S/C Switch Signal circuit. If no, go to the next step.
    7. NOTE: Before continuing, check the PCM harness connector terminals for corrosion, damage, or terminal push out. Repair as necessary.
  7. 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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