Idle Speed Stabilization (A/C Compressor Engaged) Test: Notes

Set parking brake. Run engine at idle and warm to operating temperature. Engine should idle between 670-770 RPM. If correct, test is complete. If idle speed is not correct, go to next step.
Using voltmeter, test input voltage at ECU between terminal No. 19 and ground. Readings should be 12 volts with A/C compressor on and zero volts with A/C compressor off. If reading is incorrect on either test, repair short in circuit. If reading is correct, test is complete.