Cruise Control System Revisions/Testing/Repair (08-52-88)
Reference number: 08-52-88
CRUISE CONTROL SYSTEM REVISIONS/TESTING/REPAIR
TECHNICAL SERVICE BULLETIN
CRUISE CONTROL SYSTEM REVISIONS
Model(s): 1988 Eagle Premier
Bulletin No.: 08-52-88
Group: Accessories & Electrical
Date: June 18, 1988
Subject: Cruise Control System Revisions
SERVICE INFORMATION
This bulletin is intended to update the 1988 Premier cruise control system information.
GENERAL SYSTEM OPERATION
Cruise control operation is limited to speeds above 25 to 30 MPH. At any speed above 25 to 30 MPH the system will maintain a selected road speed within 3 MPH on a level road (grades.less than 3%). A change greater than 3 MPH may be experienced when driving on unusually hilly terrain, pulling a trailer, at high altitudes or if engine performance is poor. To activate the system press the ON switch. Depressing the ON switch will activate the speed control module but will not engage the speed control. Accelerate the vehicle to the desired speed above 25-30 MPH and press the SET/COAST or the RESUME/ACCEL switch. The speed control will be activated and vehicle speed will be maintained. If a lower speed is desired while cruising at a selected speed, depress and hold the SET/COAST switch until the automobile decelerates to the desired speed. When the switch is released, I the new selected speed will be maintained as long as that selected speed is above 25-30 MPH. If a higher speed is desired, accelerate to the desired speed and press (for less than .25 seconds) either the SET/COAST or the RESUME/ACCEL switch and release. Another way of achieving an increased cruising speed would be to press and hold the RESUME/ACCEL switch (for longer than .25 seconds) causing the vehicle to accelerate. When the RESUME/ACCEL switch is released a new vehicle speed will be set. A "Tap-up" feature to obtain small incremental increases in set speed does not exist. The driver may regain normal control by pressing the OFF switch, by pressing the brake pedal (for longer than 0.5 seconds) or by shifting to Neutral. If either the brake or shifting method is used to regain control, the previously selected road speed will be maintained in memory and may be regained by pressing (for less than .25 seconds) the RESUME/ACCEL switch. The memory may be erased by pressing the OFF switch or by turning the ignition off. Neither the SET or RESUME switches will activate the system after the OFF switch has been pressed. The cruise control system has several safety features in addition to the OFF switch and brake switch. The maximum acceleration rate during a RESUME or ACCEL command is 1.5 MPH per second. The system will disengage if the vehicle speed drops below 25-30 MPH. If the vehicle accelerates or decelerates more than 10 MPH per second, the speed stored in the memory will be reduced by 10 MPH and the system will remain inactive until the vehicle speed is within 4 MPH of the reduced set speed. This may happen as a result of driving on ice. Accelerating on the down slope of a steep hill or driving through a deep puddle of water. The cruise light will illuminate whenever the cruise control system is engaged and is controlling the vehicle speed. The light will turn off when; the OFF switch is pressed, the brake is pressed (for longer than 0.5 seconds), the transmission is shifted to Neutral, if the driver accelerates the vehicle more than 4 MPH above the set speed with the accelerator pedal, or if the vehicle speed drops more than 4 MPH below the set speed (climbing a hill). The cruise light will turn on when the vehicle speed returns to within 4 MPH of the set speed.
CRUISE CONTROL SYSTEM TEST & REPAIR
- Verify an adequate and consistent vacuum to the cruise control servo.
- Verify that the cruise control cable is attached to the throttle body.
- Verify that the cruise control cable is attached to the servo by measuring the free play (5/16" to 9/16") in the cable at the throttle body mounting bracket. If greater than 9/16", remove cable housing from servo and correct.
- Verify speed sensor module operation by observing proper speedometer operation.
- Proceed to circuit check. For cruise control circuit diagrams refer to Fig 1 and Fig 2 .
CRUISE CONTROL MODULE VOLTAGE TEST
- CIRCUIT CHECK: Disconnect C572 from Cruise Control Module, put ignition switch in on position.
| TEST | OK | NOT OK |
|---|---|---|
| Terminal 28 | Battery | Check /repair Fuse 10 and WHT/BLK wire for an open |
| Measure voltage at Terminal 26 | Battery | Check/repair bulb, PNK and WHT/BLK wire for an open |
| Measure voltage between Terminal 28 and 24 with gear selector in PARK and NEUTRAL | Battery. If OK, go to test 2 | Check/repair BLK/WHT, WHT/BLK, WHT, and DK GRN/WHT wire for an open |
CRUISE CONTROL MODULE RESISTANCE TEST
- CIRCUIT CHECK: Remove negative battery terminal
| TEST | OK | NOT OK |
|---|---|---|
| Measure resistance between Terminal 21 and ground | Zero ohms | Check/repair BLK and GRY/YEL wire for an open to G101 |
| Measure resistance between Terminal 2 of C574 to Terminal 34 | Zero ohms | Adjust/replace stop lamp switch |
| Measure resistance between Terminal 2 of C574 to terminal 34 | Infinite ohms - with brake depressed | Check/repair WHT, WHT/PNK, WHT/ORN wire and stop lamp switch for a short |
| Measure resistance between Terminal 1 of C645 (Speed Sensor Module) to Terminal 23 | Zero ohms | Check/repair DK BLU/ WHT, BLUE wire for an open |
| Measure resistance between Terminals 21 and 26. Turn steer- ing wheel slowly while measuring | Open circuit in all wheel positions | Check/repair GRN/RED, RED/WHT, GRY/YEL, WHT,BLK and DK BLU wires, outer and middle slip rings and brushes for an open. Replace switch if all are OK |
| Measure resistance between Terminals 21 and 26 with cruise control OFF switch depressed. Turn steer- ing wheel slowly while measuring | ZERO ohms | Check/repair GRN/RED, RED/WHT, GRY/YEL, WHT,BLK and DK BLU wires, outer and middle slip rings and brushes for a short. Replace switches if all are OK |
| Measure resistance between Terminals 21 and 26 with cruise control ON switch depressed | Approximately 680 K ohms | Replace switch |
| Measure resistance between Terminals 21 and 26 with cruise control RESUME/ACCEL switch depressed | Approximately 5.64 K ohms | Replace switch |
| Measure resistance between Terminals 21 and 26 with cruise control SET/COAST switch depressed | Approximately 2 K ohms | Replace switch |
| Check continuity of wires and Brake Switch from Connector C572 to CYYY Terminal 30 to Terminal 1, Terminal 31 to Terminal 2, Terminal 35 to Terminal 3. Connector CYYY Terminal 4 to ground. | Zero ohms Zero ohms Zero ohms Zero ohms | Repair wire and/or Brake Switch as need- ed. Wires and Brake Switch are good Replace the servo witha known good servo. If cruise control operates replace servo. If cruise con- trol does not operate replace cruise control module. |