Component Tests and General Diagnostics

Fig. 7 Test E.7.5: ECM/PCM Input Test.:

Fig. 8 Test E.7.6: ECM/PCM Input Test.:

Fig. 9 Test E.7.7: ECM/PCM Input Test.:

To perform the switch test series, the engine must be running and the diagnostic trouble code .7.0 must be displayed on the data center panel. To begin the test sequence, depress and release the brake pedal, and the test will begin as soon as the display changes from diagnostic trouble code .7.0 to E.7.1. If the diagnostic trouble code does not change, check brake switch feed to the ECM/PCM and check for defective ECM/PCM.

The ECM/PCM will display a diagnostic trouble code for each switch, in sequence, and if the switch does not operate properly, the ECM/PCM will store the code as a diagnostic trouble code. In addition, the appropriate switch must be cycled within ten seconds after its diagnostic trouble code is displayed or the ECM/PCM will store a diagnostic trouble code associated with that switch. When performing the following test, refer to Connector Views. Under Diagrams. Connector Views

1. With diagnostic trouble code E.7.1 displayed, depress and release brake pedal again to test cruise control brake switch circuit.
2. With code diagnostic trouble E.7.2 displayed, depress accelerator pedal from idle position to open throttle, then slowly release pedal. As throttle is moved the ECM tests throttle switch for proper operation.
3. With code diagnostic trouble E.7.5 displayed, turn cruise control switch from off to on, then back to off to test operation of switch. Refer to Fig. 7 for further testing procedure. For intermittent diagnostic trouble codes proceed as follows:
a. The amber cruise-on indicator can be used to monitor the cruise dash switch status. Turn dash switch on and wiggle wiring and connectors. If switch or circuit from the fuse to switch are open, the amber light will blink out.
b. If cruise fuse blows intermittently, turn switch on, then wiggle wiring, connectors and cruise steering column switch. If circuit becomes grounded, fuse will blow.
4. With diagnostic trouble code E.7.6 displayed and with instrument panel cruise control switch on, depress and release Set/Coast button to test Set/Coast button operation. Refer to Fig. 8 for further testing procedure. For intermittent codes proceed as follows:
a. Turn cruise dash switch to on and backprobe ECM B4 with a voltmeter to ground. B4 should show 12 volts with Set/Coast depressed and 0 volts with switch released. While observing meter, cycle switch and wiggle wiring and connectors.
5. With diagnostic trouble code E.7.7 displayed and with instrument panel cruise control switch on, depress and release Resume/Acceleration switch to test operation of switch. Refer to Fig. 9 for further testing procedure. For intermittent diagnostic trouble codes proceed as follows:
a. Turn cruise dash switch to on and backprobe ECM B6 with a voltmeter to ground. B6 should show 12 volts with resume/acceleration switch depressed and 0 volts with switch released. While observing meter, cycle switch and wiggle wiring and connectors.
6. With diagnostic trouble code E.7.8 displayed, turn steering wheel to full lock in both directions, then return wheel to straight ahead position to test power steering pressure switch operation.
7. When the switch tests are completed, the ECM will go back and display diagnostic trouble codes for switches which did not test properly.
8. Check circuit between each switch that failed and the ECM, test switches individually, repair as needed, then clear diagnostic trouble codes and retest system.