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DTC P1595 & DTC P1683: Speed Control Solenoid Circuits/Speed Control Power Relay Or S/C 12V Driver

NOTE: DTC P1595 indicates speed control solenoid circuits. DTC P1683 indicates speed control power relay or s/c 12v driver.
NOTE: DTC may be caused by an improperly adjusted brake switch. For connector terminal ID, see CONNECTOR IDENTIFICATION  . For wiring diagram, see WIRING DIAGRAMS article.
NOTE: Speed Control (SC) solenoids circuits and speed control power relay or s/c 12v driver are monitored when speed control is on, vehicle speed is more than 25 MPH, engine speed is less than 5440 RPM, brakes are not applied and transaxle is in Drive. DTC may be stored in Powertrain Control Module (PCM) if PCM actuates vacuum and vent solenoids and solenoids do not operate. Possible causes are: improperly adjusted brake switch, defective brake switch, defective speed control servo, defective PCM, or defective connectors or wiring.
  1. To check brake switch adjustment, depress brake pedal. Ensure brakelights come on. Release brake pedal. Ensure brakelights go off. If brakelight operation is not as specified, go to next step. If brake switch is properly adjusted and brakelight operation is correct, go to step  4 .
  2. To adjust brake switch, hold brake pedal downward. Rotate brake switch counterclockwise approximately 30 degrees and pull brake switch rearward from mounting bracket. Brake switch is located near top of brake pedal.
  3. Pull plunger on brake switch outward to fully extended position. Depress brake pedal as far as possible. Install brake switch in mounting bracket. Ensure alignment tab on brake switch aligns with opening on mounting bracket. When brake switch is fully installed, rotate brake switch clockwise approximately 30 degrees. To ensure proper adjustment, gently pull brake pedal back toward brake switch as far as possible. DO NOT apply excessive pressure on brake pedal and brake switch. Once brake switch is properly adjusted, perform TEST VER-4A  .
  4. Disconnect speed control servo connector. Speed control servo is bolted to rear of battery tray and contains a 4-pin connector. See Fig 1 .
    Fig 1: Locating Speed Control Servo
    G98B00001Courtesy of DAIMLERCHRYSLER CORPORATION
  5. Turn ignition on with engine off. Turn speed control switch to ON position. Using voltmeter, check voltage at terminal No. 3 (Dark Blue/Red wire) on speed control servo connector. DO NOT depress brake pedal when checking voltage. If voltage is more than 10 volts, go to next step. If voltage is 10 volts or less, go to step  12 .
  6. Turn ignition off. Using ohmmeter, check resistance between ground and terminal No. 4 (Black wire) on speed control servo connector. If resistance is less than 5 ohms, go to next step. If resistance is 5 ohms or more, repair open on Black wire and ground connection. Ground connection is located near rear of cylinder head or cylinder block. Perform TEST VER-4A  .
  7. Ensure ignition is off. Disconnect PCM connectors. PCM is located between driver's side front fender and power distribution center, near battery.
  8. Reinstall speed control servo connector. Using ohmmeter, check resistance between terminal No. 5 (Yellow/Red wire) on Black PCM connector C1 and terminal No. 80 (Light Green/Red wire) on Gray PCM connector C2. DO NOT depress brake pedal when checking resistance. If resistance is 35-55 ohms, go to next step. If resistance is not 35-55 ohms, go to step  10 .
  9. Ensure PCM connectors are still disconnected. Using ohmmeter, check resistance between terminal No. 5 (Yellow/Red wire) on Black PCM connector C1 and terminal No. 56 (Tan/Red wire) on Gray PCM connector C2. DO NOT depress brake pedal when checking resistance. If resistance is not 35-55 ohms, go to next step. If resistance is 35-55 ohms, replace PCM. Perform TEST VER-4A  .
  10. Disconnect speed control servo connector. Ensure PCM connectors are still disconnected. Using ohmmeter, check resistance between terminal No. 1 (Tan/Red wire) on speed control servo connector and terminal No. 56 (Tan/Red wire) on Gray PCM connector C2. If resistance is less than 5 ohms, go to next step. If resistance is 5 ohms or more, repair open on Tan/Red wire between PCM and speed control servo. Perform TEST VER-4A  .
  11. Using ohmmeter, check resistance between terminal No. 2 (Light Green/Red wire) on speed control servo connector and terminal No. 80 (Light Green/Red wire) on Gray PCM connector C2. If resistance is less than 5 ohms, replace speed control servo. Perform TEST VER-4A  . If resistance is 5 ohms or more, repair open on Light Green/Red wire between PCM and speed control servo. Perform TEST VER-4A  .
  12. Ensure ignition is off. Disconnect brake switch connector. Brake switch is located near top of brake pedal. Turn ignition on with engine off. Turn speed control switch to ON position. Using voltmeter, check voltage at terminal No. 3 (Yellow/Red wire) on brake switch connector. If voltage is more than 10 volts, go to next step. If voltage is 10 volts or less, go to step  15 .
  13. Turn ignition off. Ensure brake switch connector and speed control servo connector are still disconnected. Using ohmmeter, check resistance between ground and terminal No. 3 (Dark Blue/Red wire) on speed control servo connector. If resistance is 5 ohms or more, go to next step. If resistance is less than 5 ohms, repair short to ground on Dark Blue/Red wire between speed control servo and brake switch. Perform TEST VER-4A  .
  14. Using ohmmeter, check resistance between terminal No. 4 (Dark Blue/Red wire) on brake switch connector and terminal No. 3 (Dark Blue/Red wire) on speed control servo connector. If resistance is less than 5 ohms, replace brake switch. Perform TEST VER-4A  . If resistance is 5 ohms or more, repair open on Dark Blue/Red wire between brake switch and speed control servo. Perform TEST VER-4A  .
  15. Turn ignition off. Ensure brake switch connector and speed control servo connector are still disconnected. Using ohmmeter, check resistance between ground and terminal No. 4 (Dark Blue/Red wire) on brake switch connector. If resistance is 5 ohms or more, go to next step. If resistance is less than 5 ohms, repair short to ground on Dark Blue/Red wire between speed control servo and brake switch. Perform TEST VER-4A  .
  16. Turn ignition off. Disconnect PCM connectors. PCM is located between driver's side front fender and power distribution center, near battery. Ensure brake switch connector is still disconnected.
  17. Using ohmmeter, check resistance between terminal No. 3 (Yellow/Red wire) on brake switch connector and terminal No. 5 (Yellow/Red wire) on Black PCM connector C1. If resistance is 5 ohms or more, repair open on Yellow/Red wire between PCM and brake switch. Perform TEST VER-4A  . If resistance is less than 5 ohms, replace PCM. Perform TEST VER-4A  .
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