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SERVO VACUUM TEST (1) Turn ignition switch to the ON position with- out starting engine. Activate speed control ON (2) Disconnect the four-way electrical connector and the vacuum harness at the servo (Fig. 4). (3) Connect a jumper wire from Pin 3 of the servo to Pin 3 of the wire connector. (4) Ground Pins 2 and 4 in the servo. Do not con- nect pin 1. (5) Connect a hand held vacuum pump to the vac- uum nipple and apply 10 - 15 inches of vacuum. (6) If servo pulls cable, replace servo. as long as the vacuum pump is connected. After one (9) Disconnect jumper from pin 3. Cable should return to rest position. If not, replace servo. (10) Connect 4 way electrical connector and vac- uum harness to servo. STOP LAMP SWITCH TEST (1) Remove the stop lamp switch refer to Stop Switch Removal/Installation in this section. Discon- (2) With switch plunger released, there should be continuity between Pin 5 and Pin 6. (3) With switch plunger depressed, there should be continuity: • Between Pin 1 and Pin 2. • Between Pin 3 and Pin 4. (4) If the above results are not obtained, the stop lamp switch is defective or out of adjustment. (5) Stop lamp switch adjustment is detailed in Group 5, Brakes. VACUUM SUPPLY TEST (1) Disconnect vacuum hose at the servo and install a vacuum gauge in the hose (Fig. 6). (2) Start engine and observe gauge at idle. Vac- uum gauge should read at least ten inches of mer- (3) If vacuum does not meet this requirement, check and correct the following vacuum leaks in the Fig. 4 Servo Harness Connector Fig. 5 Stop Lamp Wiring Fig. 6 Vacuum Gauge Test—Typical 8H - 6 VEHICLE SPEED CONTROL SYSTEM 300M DIAGNOSIS AND TESTING (Continued) |