Schematic Reference: HVAC Schematics

Definition: Control head illumination/display does not operate properly.

Did you perform the HVAC Diagnostic System Check?

Go to Step 2

Go to Diagnostic System Check - HVAC Systems - Automatic

When performing the Diagnostic System Check, was DTC B2646 displayed for the Instrument Panel Module?

Go to Diagnostic Trouble Code (DTC) List in Lighting Systems

Go to Step 3

1. Install a scan tool.
2. Turn ON the ignition, with the engine OFF.
3. With a scan tool, perform the Display(s) Test command in Instrument Panel Module Special Functions.

Do all HVAC control module segments illuminate?

Go to Step 4

Go to Step 7

When performing the Display(s) Test Instrument Panel Module command, do all other VF displays illuminate?

Go to Step 5

Go to Symptoms - Lighting Systems in Lighting Systems

1. Cover the sunload sensor assembly.
2. Turn ON the lights.

Is there backlighting?

Go to Step 6

Go to Symptoms - Lighting Systems in Lighting Systems

Adjust the dimming control from minimum to maximum intensity.

Does the VF display increase and decrease in intensity?

System OK

Go to Step 7

Inspect for poor connections at the harness connector of the HVAC control module. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs in Wiring Systems.

Did you find and correct the condition?

Go to Step 9

Go to Step 8

Replace the HVAC control module. Refer to HVAC Control Module Replacement .

Did you complete the repair?

Go to Step 9

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Operate the system in order to verify the repair.

Did you correct the condition?

System OK

Go to Step 2