CCS-3 Test - Cruise Control Servo Ground Circuit Check
- Turn ignition off. Disconnect cruise control servo electrical connector. Connect an ohmmeter between Black wire in cruise control servo harness connector and ground. See Fig 1 . If ohmmeter is not showing continuity, repair Black wire (open circuit to wiring harness splice). If ohmmeter is showing continuity, reconnect electrical connector and go to next step.
- Connect diagnostic read-out box to diagnostic connector in engine compartment. Place system in Switch Test Mode. See ENTERING ON-BOARD DIAGNOSTICS under TESTING & DIAGNOSIS in this article. Press brake pedal down. If display on diagnostic read-out box changes as pedal is depressed (not important what the reading is, just that display changes), go to step 4). If display on diagnostic read-out box does not change as pedal is depressed, go to next step.
- Turn ignition switch off. Disconnect 60-pin connector from SMEC. Connect an ohmmeter between cavity No. 29 of 60-pin connector and ground. See Fig 3 . Depress brake pedal, and then release. If ohmmeter does not register continuity when brake pedal is depressed and does register continuity when pedal is released, replace SMEC (defective logic board). Ensure terminal in cavity No. 29 of 60-pin connector is not damaged, causing a poor connection, before replacing SMEC. If ohmmeter does not register as indicated, check wire at cavity No. 29 of 60-pin connector (open circuit to stoplight ground eyelet).
- With diagnostic read-out box connected to diagnostic connector in engine compartment, place system in Switch Test Mode. See ENTERING ON-BOARD DIAGNOSTICS under TESTING & DIAGNOSIS in this article. Place gear selector lever in Park, Reverse, Neutral, and Drive while observing diagnostic read-out box display. If display on diagnostic read-out box changes as gear selector lever is moved from Park to Reverse, Reverse to Neutral, Neutral to Drive, and Drive to Park (not important what the reading is, just that display changes), go to step 6). If display on diagnostic read-out box does not change when gear selector lever is moved, go to next step.
- Turn ignition off. Disconnect 60-pin connector from SMEC. Connect an ohmmeter between cavity No. 30 of 60-pin connector and ground. See Fig 4 . Disconnect battery quick disconnect. Turn ignition switch to "RUN" position. While observing ohmmeter, place gear selector in Park, Reverse, Neutral, and Drive. If ohmmeter shows continuity in all gear selector positions, check wire in cavity No. 30 (short to ground), and check for bad neutral safety switch. If ohmmeter shows no continuity in all gear selector positions, repair wire in cavity No. 30 (open circuit to neutral safety switch).
- Reconnect cruise control servo electrical connector. Connect diagnostic read-out box to diagnostic connector in engine compartment. Disconnect cruise control servo vacuum supply hose from power brake booster and connect an auxiliary vacuum supply. See Fig 5 . Place system in ATM Test Mode "08". See ENTERING ON-BOARD DIAGNOSTICS under TESTING & DIAGNOSIS in this article. Continuously apply vacuum to cruise control servo.
- If throttle is opening and closing as cruise control system is turning on and off (vacuum continuously applied), check vacuum supply to cruise control servo. Also check speed sensor operation by entering Engine Running Test Mode "71". See ENTERING ON-BOARD DIAGNOSTICS under TESTING & DIAGNOSIS in this article. MPH on diagnostic read-out box display must be stable at all times. If not, replace speed sensor. If throttle is not opening and closing as cruise control system is turning on and off (vacuum continuously applied), replace cruise control servo. Before replacing servo, ensure cruise control cable is properly adjusted, or is not broken. Also ensure there are no leaks or restrictions in vacuum supply hose to servo.