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Test TC-15A - Speed Control Power Relay Circuit & Speed Control Solenoid Circuits

NOTE: For connector terminal identification, see CONNECTOR IDENTIFICATION . For wiring diagram, see WIRING DIAGRAMS .
  1. Turn Speed Control (SC) on. Using scan tool, actuate Speed Control (SC) vent solenoid. If SC servo clicks, go to next step. If SC servo does not click, go to step 8).
  2. Wiggle wiring harness between SC servo, brake switch and Powertrain Control Module (PCM). If wiggling did not cause an interruption of SC servo actuation, go to next step. If wiggling caused an interruption of SC servo actuation, repair wiring harness as necessary where wiggling caused problem to appear. Perform TEST SC-VER .
  3. Using scan tool, actuate SC vacuum solenoid. If SC servo clicks, go to next step. If SC vacuum solenoid does not click, go to step 8).
  4. Wiggle wiring harness between SC servo and brake switch to PCM while scan tool is still actuating SC vacuum solenoid. If wiggling did not cause an interruption of SC servo actuation, go to next step. If wiggling caused an interruption of SC servo actuation, repair wiring harness as necessary where wiggling caused problem to appear. Perform TEST SC-VER .
  5. Condition to set trouble code is not present at this time. If SPEED CONTROL SOLENOID CIRCUITS DTC is being diagnosed, go to next step. SPEED CONTROL POWER RELAY CIRCUIT DTC sets when speed control power supply circuit is either open or shorted to ground. Possible causes are: open or shorted power supply circuit or failed SC vent solenoid. Go to step 7).
  6. SPEED CONTROL SOLENOID CIRCUITS DTC sets when PCM actuates vacuum and vent solenoids, but solenoids do not respond. Possible causes are: solenoid control circuit open or shorted, vacuum or vent solenoid open or shorted, open or shorted speed control power supply circuit or PCM failure. Go to next step.
  7. Inspect all related wiring and connectors and repair as necessary. If related wiring and connectors were repaired, perform TEST SC-VER . If no problems were found with wiring and connectors, test is complete. Perform TEST SC-VER .
  8. Disconnect speed control servo 4-pin connector. DO NOT  depress brake pedal during testing. Turn ignition on with engine off. Turn speed control switch on. Using a voltmeter, check voltage on speed control servo 4-pin connector Dark Blue/Red wire. If voltage is 10 volts or less, go to next step. If voltage is more than 10 volts, go to step 12).
  9. Turn ignition off. Using a ohmmeter, check resistance of speed control servo 4-pin connector Dark Blue/Red wire. If resistance is 5 ohms or more, go to next step. If resistance is less than 5 ohms, repair short to ground on appropriate wire. Perform TEST SC-VER .
  10. Disconnect brake switch connector. Brake switch connector is located near top of brake pedal. Turn ignition on with engine off. Using a voltmeter, check voltage on brake switch connector Yellow/Pink wire. If voltage is 10 volts or less, go to next step. If voltage is more than 10 volts, perform TEST TC-15B .
  11. Turn ignition off. Disconnect Powertrain Control Module (PCM) connector. Using a ohmmeter, check resistance of SC power supply circuit Yellow/Pink wire between PCM connector terminal No. 62 and brake switch connector. If resistance is less than 5 ohms, replace PCM. Perform TEST SC-VER . If resistance is 5 ohms or more, repair open SC power supply circuit. Perform TEST SC-VER .
  12. Using a ohmmeter, check resistance of SC servo connector Black wire. If resistance is less than 5 ohms, go to next step. If resistance is 5 ohms or more, repair open Black wire. Perform TEST SC-VER .
  13. Disconnect Powertrain Control Module (PCM) connectors. Using a ohmmeter, check resistance of SC vacuum solenoid control circuit Tan/Red wire between PCM connector terminal No. 78 and speed control servo 4-pin connector. If resistance is less than 5 ohms, go to next step. If resistance is 5 ohms or more, repair open SC vacuum solenoid control circuit. Perform TEST SC-VER .
  14. Using a ohmmeter, check resistance of SC vent solenoid control circuit Light Green/Red wire between PCM connector terminal No. 80 and speed control servo 4-pin connector. If resistance is less than 5 ohms, go to next step. If resistance is 5 ohms or more, repair open SC vent solenoid control circuit. Perform TEST SC-VER .
  15. Using a ohmmeter, check resistance of SC vacuum solenoid control circuit Tan/Red wire at speed control servo 4-pin connector. If resistance is 5 ohms or more, go to next step. If resistance is less than 5 ohms, repair short to ground on SC vacuum solenoid control circuit. Perform TEST SC-VER .
  16. Using a ohmmeter, check resistance of SC vent solenoid control circuit Light Green/Red wire at speed control servo 4-pin connector. If resistance is less than 5 ohms, repair short to ground on SC vent solenoid control circuit. Perform TEST SC-VER . If resistance is 5 ohms or more, replace speed control servo. Perform TEST SC-VER .
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