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DTC P1595: Speed Control Solenoid Circuits

NOTE: For connector terminal ID, see CONNECTOR IDENTIFICATION  . For wiring diagram, see WIRING DIAGRAMS article.
NOTE: Speed control solenoids circuits are monitored when ignition is on, speed control is on and vehicle speed is more than 35 MPH. DTC may be stored in Powertrain Control Module (PCM) if PCM actuates speed control 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. Turn ignition on with engine off. Using scan tool, actuate speed control vent solenoid and listen for operating sound (click) at speed control servo. Speed control servo is at passenger's side rear corner of engine compartment on the firewall. See Fig 1 . If operating sound is heard at speed control servo, go to next step. If operating sound is not heard at speed control servo, go to step  10 .
    Fig 1: Locating Speed Control Servo
    G00014910Courtesy of DAIMLERCHRYSLER CORPORATION
  2. Ensure ignition is on with engine off. Using scan tool, actuate speed control vacuum solenoid and listen for operating sound (click) at speed control servo. If operating sound is heard at speed control servo, go to next step. If operating sound is not heard at speed control servo, go to step  6 .
  3. Ensure ignition is on with engine off. Using scan tool, actuate speed control vent solenoid. Wiggle wiring harness and connectors between speed control servo, brake switch and PCM while checking for interruption of speed control vent solenoid actuation. Brake switch is located near top of brake pedal. PCM is located at passenger's side front corner of engine compartment on inner fender panel. If speed control vent solenoid actuation was not interrupted while wiggling wiring harness and connectors, stop actuation of speed control vent solenoid. Go to next step. If speed control vent solenoid actuation was interrupted while wiggling wiring harness and connectors, stop actuation of speed control vent solenoid. Repair wiring or connectors as necessary. Perform TEST VER-4  .
  4. Turn ignition off. Inspect wiring harness and connectors between speed control servo, brake switch and PCM. If no problems exist, go to next step. If any problems exist, repair wiring or connectors as necessary. Perform TEST VER-4  .
  5. Turn ignition on with engine off. Using scan tool, actuate speed control vacuum solenoid. Wiggle wiring harness and connectors between speed control servo, brake switch and PCM while checking for interruption of speed control vacuum solenoid actuation. If speed control vacuum solenoid actuation was not interrupted while wiggling wiring harness and connectors, stop actuation of speed control vacuum solenoid. Test is complete. If speed control vacuum solenoid actuation was interrupted while wiggling wiring harness and connectors, stop actuation of speed control vacuum solenoid. Repair wiring or connectors as necessary. Perform TEST VER-4  .
  6. Turn ignition off. Disconnect speed control servo connector. Turn ignition on with engine off. Turn speed control on/off switch to ON position. Using scan tool, actuate speed control vacuum solenoid. Using 12-volt test light, check for voltage at terminal No. 3 (Dark Blue/Red wire) on speed control servo connector. DO NOT depress brake pedal when checking voltage. If test light illuminates brightly, go to next step. If test light does not illuminate brightly, go to step  14 .
  7. Turn ignition off. Ensure speed control servo connector is still disconnected. Using 12-volt test light connected to battery voltage, check for voltage at terminal No. 4 (Black wire) on speed control servo connector. If test light illuminates, go to next step. If test light does not illuminate, repair open on Black wire between speed control servo and ground connection. Ground connection is located on inside of passenger's side front fender. Perform TEST VER-4  .
  8. Ensure ignition is off and speed control servo connector is still disconnected. Disconnect PCM connectors. PCM is located at passenger's side front corner of engine compartment on inner fender panel. Using ohmmeter, check resistance between terminal No. 1 (Tan/Red wire) on speed control servo connector and terminal No. 4 (Tan/Red wire) on PCM connector C3. If resistance is less than 5 ohms, go to next step. If resistance 5 ohms or more, repair open on Tan/Red wire between speed control servo and PCM. Perform TEST VER-4  .
  9. Ensure speed control servo connector and PCM connectors are still disconnected. Using ohmmeter, check resistance between ground and terminal No. 1 (Tan/Red wire) on speed control servo connector. If resistance is 5 ohms or more, replace speed control servo. Perform TEST VER-4  . If resistance is less than 5 ohms, repair short to ground on Tan/Red wire between speed control servo and PCM. Perform TEST VER-4  .
  10. Turn ignition off. Disconnect speed control servo connector. Turn ignition on with engine off. Turn speed control on/off switch to ON position. Using scan tool, actuate speed control vent solenoid. Using 12-volt test light, check for voltage at terminal No. 3 (Dark Blue/Red wire) on speed control servo connector. DO NOT depress brake pedal when checking voltage. If test light illuminates brightly, go to next step. If test light does not illuminate brightly, go to step  14 .
  11. Turn ignition off. Ensure speed control servo connector is still disconnected. Using 12-volt test light connected to battery voltage, check for voltage at terminal No. 4 (Black wire) on speed control servo connector. If test light illuminates, go to next step. If test light does not illuminate, repair open on Black wire between speed control servo and ground connection. Ground connection is located on inside of passenger's side front fender. Perform TEST VER-4  .
  12. Ensure ignition is off and speed control servo connector is still disconnected. Disconnect PCM connectors. PCM is located at passenger's side front corner of engine compartment on inner fender panel. Using ohmmeter, check resistance between terminal No. 2 (Light Green/Red wire) on speed control servo connector and terminal No. 5 (Light Green/Red wire) on PCM connector C3. If resistance is less than 5 ohms, go to next step. If resistance 5 ohms or more, repair open on Light Green/Red wire between speed control servo and PCM. Perform TEST VER-4  .
  13. Ensure speed control servo connector and PCM connectors are still disconnected. Using ohmmeter, check resistance between ground and terminal No. 2 (Light Green/Red wire) on speed control servo connector. If resistance is 5 ohms or more, replace speed control servo. Perform TEST VER-4  . If resistance is less than 5 ohms, repair short to ground on Light Green/Red wire between speed control servo and PCM. Perform TEST VER-4  .
  14. Brake switch adjustment should be checked. Ensure brake switch connector is installed. To check brake switch adjustment, depress brake pedal. Ensure brakelights come on. Release brake pedal. Ensure brakelights go off. If brake switch is properly adjusted and brakelight operation is as specified, go to next step. If brakelight operation is not as specified, replace brake switch, as brake switch is nonadjustable and can only be adjusted when NEW brake switch is installed. Perform TEST VER-4  .
  15. Ensure ignition is off. Disconnect brake switch connector. Using ohmmeter, check resistance between terminals on brake switch that correspond with terminals No. 3 (Dark Blue/Red wire) and No. 4 (Yellow/Red wire) on brake switch connector. DO NOT depress brake pedal when checking resistance. If resistance is less than 5 ohms, go to next step. If resistance is 5 ohms or more, replace brake switch. Perform TEST VER-4  .
  16. Ensure ignition is off and brake switch connector is still disconnected. Disconnect PCM connectors. PCM is located at passenger's side front corner of engine compartment on inner fender panel. Using ohmmeter, check resistance between ground and terminal No. 4 (Yellow/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 Yellow/Red wire between brake switch and PCM. Perform TEST VER-4  .
  17. Ensure brake switch connector and PCM connectors are still disconnected. Using ohmmeter, check resistance between terminal No. 4 (Yellow/Red wire) on brake switch connector and terminal No. 11 (Yellow/Red wire) on PCM connector C3. If resistance is less than 5 ohms, go to next step. If resistance 5 ohms or more, repair open on Yellow/Red wire between brake switch and PCM. Perform TEST VER-4  .
  18. Ensure brake switch connector is still disconnected. Disconnect speed control servo connector. 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 between brake switch and speed control servo. Perform TEST VER-4  .
  19. Ensure brake switch connector and speed control servo connectors are still disconnected. Using ohmmeter, check resistance between terminal No. 3 (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 PCM. Perform TEST VER-4  . If resistance 5 ohms or more, repair open on Dark Blue/Red wire between brake switch and speed control servo. Perform TEST VER-4  .
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