Service Procedure

Start by running speed control self test diagnostics. The self test diagnostics are a key tool in quickly and accurately diagnosing speed control system faults. Self test diagnostics are also the basis for starting speed control trouble shooting.

NOTE
DIAGNOSTIC FLASH CODES AND/OR DTCS ARE NOT AVAILABLE TO ASSIST WITH DIAGNOSIS OF THE 6-PIN SYSTEM. THE DYNAMIC THROTTLE PULL AT THE END OF THE SELF TEST IS THE ONLY CONFIRMATION AVAILABLE TO VERIFY IF THE SYSTEM IS OPERATING CORRECTLY AT THE TIME OF SERVICE.

WARNING
THIS TEST IS A KEY ON ENGINE OFF (KOEO) TEST THAT IS CONDUCTED ONLY WHILE PARKED WITH THE PARKING BRAKE FULLY ENGAGED. FAILURE TO FOLLOW THESE INSTRUCTIONS MAY RESULT IN PERSONAL INJURY.

NOTE
THE SELF-TEST IS COMPRISED OF TWO PARTS. THE FIRST PART IS A STATIC CHECK OF THE SPEED CONTROL ELECTRONICS MODULE AND SYSTEM. THE SECOND PART IS A DYNAMIC PULL-TEST TO CHECK THE ACTUATOR MOTOR AND GEAR MECHANISM.

NOTE
THE MODULE TIMES OUT IF EACH BUTTON IS NOT PRESSED WITHIN 1 SECOND OF THE PREVIOUS BUTTON. IF A MODULE TIME OUT OCCURS (SPEED CONTROL LAMP STOPS FLASHING PART WAY THROUGH THE TEST), THE PROCEDURE MUST BE RE-INITIATED.

NOTE
REVIEW THE FOLLOWING STEPS BEFORE CARRYING OUT THE SELF-TEST DIAGNOSTIC PROCEDURE.

1. Self Test Diagnostic Procedure - Static Test

NOTE
FOR 6-PIN SERVOS, THE LAMP FLASH IS TOO SLOW AND MUST BE IGNORED. SWITCHES MUST BE PRESSED WITHIN ONE SECOND OF EACH OTHER. WAITING FOR THE CLUSTER LAMP TO FLASH COULD RESULT IN A SELF TEST TIME OUT CONDITION. IGNORE CLUSTER LAMP FLASHES BUT OBSERVE DYNAMIC THROTTLE PULL WHICH OCCURS AT THE END OF THE BUTTON SEQUENCE.

a. Connect the diagnostic scan tool (DST) to a power source that is not interrupted when the ignition switch changes positions. With the ignition switch in the RUN position, set the DST to monitor the powerirain control module (PCM) throttle position PID while the speed control actuator carries out the self-test.

b. Enter self-test diagnostics by firmly pressing and holding the speed control OFF switch while quickly cycling the ignition switch from RUN-to-OFF-to-RUN, making sure the engine does not start and is not running.

c. The speed control indicator lamp on the instrument panel will flash once to indicate that the speed control module has entered the diagnostic mode. Release the OFF switch. If 5 flashes are displayed at this point, a speed control subsystem concern exists. Refer to the Symptom Chart in the vehicle WSM.





d. Then firmly press and release the remaining switches within 1 second of other following the sequence in Figure 1.

NOTE
MONITOR THE PCM THROTTLE POSITION PID AFTER THE LAST BUTTON IS PRESSED.

NOTE
IF THE SELF-TEST WILL NOT START OR CANNOT BE COMPLETED AFTER MULTIPLE ATTEMPTS, GO TO THE VEHICLE WSM SYMPTOM CHART.

2. Self Test Diagnostic Procedure - Dynamic Test

NOTE
THE DYNAMIC TEST OCCURS AUTOMATICALLY AFTER THE STATIC TEST COMPLETES. IF THE STATIC TEST FAILS, THERE WILL BE NO DYNAMIC PULL TEST.

a. Within .25 seconds after the static test has completed, the speed control actuator carries out a dynamic pull test. The actuator automatically pulls the speed control cable .04 to .39" (1 to 10 mm) to move the throttle from the idle position and then releases the speed control cable returning the throttle to the idle position. You should hear one sharp clicking sound which indicates the servo clutch engagement followed by a gear sound indicating the servo motor turning (try this on a known good unit for reference). If you have one sound without the other, it will help indicate which circuits are inoperative.

b. If the throttle position PID voltage value does not change during the dynamic throttle pull, GO to the WSM Symptom Chart Section for Dynamic pull test failure.