Circuit Description
The RH sun load sensor is a light sensitive photodiode that controls signal voltage to the Instrument Panel Integration Module (IPM). This photodiode is different from standard thermistor sensors and resistance measurements will not produce accurate results. The IPM monitors voltage on circuit 1548 to the sensor. When the sensor is in direct sun light the IPM 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 IPM. |
| • | The default valve will allow the system to operate. |
Conditions for Clearing the MIL/DTC
| • | Using a scan tool. |
| • | A current DTC will clear when the diagnostic runs and does not fail. |
| • | IPM battery voltage is interrupted. |
Test Description
The numbers below refer to the step numbers on the diagnostic table.
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This step determines whether the Body Control Module (BCM) Diagnostic System Check was performed.
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This step determines whether the sensor is operational.
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This step determines that the DTC was not set in error.
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This step determines if the malfunction is the sensor or an open or a short in a circuit.
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This step determines if the HCM, or an open or a short causes the malfunction.
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The scan tool verifies proper sensor operation. Clear all the DTC's after the repair procedures are complete.
Step | Action | Value(s) | Yes | No |
|---|---|---|---|---|
Was the BCM diagnostic system check performed? | -- | Go to Step 2 | ||
Did the sensor counts increase from the noted value? | -- | Go to Step 3 | Go to Step 4 | |
Did the DTC reset? | -- | Go to Step 4 | Go to Intermittents and Poor Connections in HVAC Systems with A/C-Automatic | |
Is the voltage within the specified range? 4 | 4.5-5.5 V | Go to Step 8 | Go to Step 5 | |
5 | Measure the voltage between sun load sensor harness connector terminal A and ground. Is the voltage within the specified range? | 4.5-5.5 V | Go to Step 9 | Go to Step 6 |
6 | Measure the voltage between IPM terminal B3 and ground. Is the voltage within the specified range? | 4.5-5.5 V | Go to Step 7 | Go to Step 10 |
7 | Repair an open or short in CKT 1548 (GRY). Is the open repaired in CKT 1548 (GRY)? | -- | Go to Step 12 | -- |
8 | Replace the RH sun load sensor. Refer to Sun Load Sensor Replacement in HVAC Systems with A/C-Automatic. Is the repair complete? | -- | Go to Step 12 | -- |
Are all of the HVAC sensor DTCs present? | -- | Go to Step 10 | Go to Step 11 | |
10 |
Is the repair complete? | -- | Go to Step 12 | -- |
11 | Repair an open or short in CKT 61 (YEL). Is the open repaired in CKT 61 (YEL)? | -- | Go to Step 12 | -- |
Is the system operating correctly? | -- | -- |
