Code I022 Panel Dimming Switch Pot Circuit

1. Turn ignition switch and headlight switch on. Enter self-diagnostics. See ENTERING SELF-DIAGNOSTICS under SELF-DIAGNOSTICS. Monitor the ID42 Dimming Input. If display value is "4" or less, turn off headlights. Remove headlight switch from panel leaving switch connected to harness and go to next step. If display value is "5" or more, no problem is found.
2. If no problem is found, check for an intermittent problem by turning dimmer switch through its full travel, watching for sudden jumps in display numbers. If a failure is induced, display reading will jump from normal value to a reading value less than "4". Remove headlight switch and instrument panel top cover. Ensure good terminal contacts at headlight switch connector and at IPC connector cavities D3 and C10. See Fig 1. Wiggle test related wiring while observing IPC Data value ID42.
3. If display value is "4" or less, turn headlights on. Using voltmeter, connect one lead to ground and backprobe headlight switch 4-cavity connector terminal "C". See Fig 2. Rotate dimmer switch. If voltage changes with dimmer switch movement, go to step 6). If voltage does not change or is not present, leave headlights on.
4. Using both DVOM probes, backprobe headlight switch 4-cavity connector terminal "B" to "A". If voltage is less than 8 volts, go to next step. If voltage is 8 volts or more, check for faulty connections at headlight switch 4-cavity connector. If all connections are good, replace headlight switch. A grounded Gray wire circuit cannot cause this condition.
5. If voltage is less than 8 volts, leave headlights on. Using DVOM, backprobe headlight switch 4-cavity connector terminal "B" to ground. If voltage is less than 8 volts, repair open in Brown wire circuit between headlight switch and IPC. See Fig 2. If voltage is 8 volts or more, repair open in Black wire ground circuit from headlight switch.
6. If voltage changes with dimmer switch movement, remove DVOM from headlight switch. Using DVOM, backprobe IPC White connector terminal C10 to ground. See Fig 1. Rotate dimmer switch. If no voltage exists, repair open in Gray wire circuit between headlight switch and IPC.
7. If voltage changes with dimmer switch, check IPC connector terminals for faulty terminals/connections. If connections are good, replace IPC. After all repairs are completed, clear all codes and verify correct operation.

Fig 1: Identifying IPC Harness Connector Terminals

Courtesy of GENERAL MOTORS CORP.

Fig 2: Code I022 Wiring Circuit

Courtesy of GENERAL MOTORS CORP.

NOTE: Following test should be used when multiple codes exist.