Cruise Control - System Diagnosis Revision
86amcjeep02FEBRUARY 1986 000 902
1986 COMANCHE 60 SERIES
7E
ELECTRICAL Attention: Workshop, Parts Department
CRUISE CONTROL SYSTEM DIAGNOSIS
FIGURE 1 - CRUISE CONTROL TESTER:
A revised method of diagnosing the cruise control system using the AM PC-1-R Cruise Control Tester, (Fig. 1), has been developed. This will improve cruise control component diagnosis and repair.
The AM PC-1-R Cruise Control Tester will be required to perform these diagnostic tests. The chart must be used in conjunction with the Comanche Electrical Troubleshooting Manual and MR 277 workshop manual.
Also included in this I.S. Note is an easier procedure for performing cruise control module tests. Use this to verify that the module is functioning.
FIGURE 2 - WIRE HARNESSCONNECTOR:
PROCEDURE
1. Disconnect the wire harness connector from the cruise control module (Fig. 2).
CAUTION: When disconnecting the wire harness connectors, do not pull on the wires. Pull only on the connectors.
2. Disconnect and connect all wire harness connectors several times to remove terminal oxidation/corrosion.
3. Plug the tester connector into the cruise control module.
4. Conduct the following tests.
DIAGNOSTIC TESTS USING AM PC-1-R CRUISE CONTROL TESTER
LAMP ON
MINIMUM OPERATION
REQUIRED TO TURN ON LAMP 1 2 3 4 5 6
A. CRUISE SWITCH ON X
^ Set Switch Depressed
B. CRUISE SWITCH ON X
C. IGNITION SWITCH ON X X
^ Depress Brake or Clutch to Turn OFF
D. CRUISE SWITCH RESUME/ACCELERATE X X
CRUISE CONTROL SERVO CHECKS
E. CRUISE SWITCH RESUME/ACCELERATE X X
^ Engine Running
WARNING: Servo will pull throttle wide open. Keep RPM's at safe limit by releasing cruise switch.
If the tester lamp results are NOT as desired, make the following checks and either repair or replace as described.
NOTE: All voltages measured must be at battery potential, (voltage). If volt/ohm readings are incorrect, check that circuit for an open or short using the appropriate Electrical Troubleshooting Manual.
Lamp No. 1 OFF - Set Switch
^ Check voltage from HAZ/STOP and inline fuses at terminal 14 (DK GRN), (cruise switch ON) to ground terminal 1 (LT GRN).
Lamp No. 2 OFF - Cruise Switch/Speed Sensor
^ Check voltage from HAZ/STOP and inline fuses at terminal 5 (BRN), cruise switch ON, to ground 1 (LT GRN).
^ Check resistance between terminals 2 (GRY) and 3 (BLU), 15-50 ohms.
Lamp No. 3 OFF - Brake Bulb(s) Ground
^ With ignition ON, jumper terminals 7 (WHT W/TR) and 13 (LT BLU W/TR); if brake lights do not turn ON check gauges, fuses and brake switch connections.
Lamp No. 4 OFF - Throttle Position Feedback Sensor
^ Check voltage from gauges fuse (ignition ON) at terminal 7 (WHT W/TR) to ground terminal 1 (LT GRN).
^ Check resistance between terminal 2 (GRY) and 11 (TAN) 240-4K ohms. 280-430 ohms = idle. 4K (4000) ohms - wide open throttle.
Lamp No. 5 OFF - Resume/Accelerate/ Vent Valve
^ Check voltage from HAZ/STOP and inline fuses (cruise switch at R/A) at terminal 10 (YEL) to ground terminal 1 (LT GRN).
^ Check resistance between terminals 6 (WHT) and 12 (ORN), 30-50 ohms.
^ Terminals 6 (WHT) and 12 (ORN) to ground must have infinite resistance, (OPEN).
Lamp No. 6 OFF - Resume/Accelerate/ Charge Valve
^ Check voltage from HAZ/STOP and inline fuses (cruise switch at R/A) at terminal 10 (YEL) to ground terminal 1 (LT GRN).
^ Check resistance between terminals 4 (RED) and 12 (ORN), 30-50 ohms.
^ Terminals 4 (RED) and 12 (ORN) to ground must have infinite resistance, (OPEN).
Cruise Control Servo Checks
^ Check servo cable for breaks and hook-up.
^ Check engine vacuum can and hose connections (small hose).
^ Pinch brake vent (large hose) at servo and repeat test.
If servo operates, adjust brake vent hose valve (on brake sled).
If hose is kinked, check routing. If it is cut, replace with new harness.
Cruise Control Module Test
The cruise control module adjustments are preset by the manufacturer. If all other components of the system appear to be functioning normally and the cruise control remains inoperative, perform the following adjustments to determine if the module is functional.
CAUTION: The adjustments are extremely delicate. Insert the screwdriver into the slots VERY CAREFULLY. Do not push hard or turn hard against the stops. The arms have a maximum turning angle of 270 degrees (threequarter turn).
Verify if the cruise control module is defective by using the indicated settings:
FIGURE 3 - CRUISE CONTROL MODULES:
Turn the centering adjustment to the 10 o'clock position (Fig. 3).
Turn the low speed switch adjustment to the 10 o'clock position (Fig. 3).
Turn the sensitivity adjustment full clockwise (Fig. 3).
NOTE: The adjustments may not be precisely correct for the vehicle, but are acceptable to determine if the regulator module is functioning. The need for more precise adjustments can be determined by a road test.
If the adjustments have no effect on the cruise control operation, replace the cruise control module.
NOTE: The cruise control module is the only component of the system that cannot be isolated and tested separately. It must be tested while connected to the other components of the system.
TOOL ORDERING INFORMATION
DESCRIPTION QUANTITY PART NUMBER
*TESTER, AM PC-1-R CRUISE CONTROL 1 8981 320 815
*Available from your PDC
FILING INSTRUCTIONS
Record this information on page C-101 and file in the July 1985 edition of the MR 277 workshop manual.