B1328 - HVAC Systems - Automatic

Diagnostic Trouble Code Chart:

Wiring Schematic:

CIRCUIT DESCRIPTION
The Passenger sun load sensor is a light sensitive photodiode that controls signal voltage to the HVAC Control Module (HCM). This photodiode is different from standard thermistor sensors and resistance measurements will not produce accurate results. The HCM monitors voltage on circuit 1548 to the sensor. When the sensor is in direct sun light the HCM reads a low signal voltage at terminal B3, connector C2. When the sensor is shaded, the signal voltage increases. Signal voltage will vary from 5 V (open circuit) to 0 V (short circuit).

CONDITIONS FOR SETTING THE DTC
^ The ignition is ON.
^ Circuit shorted or open.

ACTION TAKEN WHEN THE DTC SETS
^ A default value of dark or no sun load will be used by the HCM.
^ The default value will allow the system to operate.

CONDITIONS FOR CLEARING THE DTC
^ Using a Scan Tool.
^ A history DTC will clear when 40 consecutive ignition cycles have occurred without a malfunction.
^ HCM battery voltage is interrupted.

TEST DESCRIPTION
The numbers below refer to the step numbers on the diagnostic table.
1. Perform the Body Control Module (BCM) diagnostic system check before continuing with the diagnosis of this DTC.
2. Determines whether the sensor is operational.
3. Determines that the DTC was not set in error.
4. Determines if the malfunction is the sensor or an open or a short in a circuit.
9. Determines if the HCM or an open or short is causing the malfunction.
12. The Scan Tool checks for proper sensor operation. Clear all the DTC's after the repair procedures are complete.