Circuit Description
The sun load temperature sensor is a reverse bias photo diode that measures sun load on the vehicle. The sensor is an input to the electronic climate control (ECC) module. High sensor impedance equates to full darkness. Low sensor impedance equates to bright sunlight.
Conditions for Setting the DTC
With the ignition ON, the ECC module will detect DTC B0186 any time that CKT 590 is at or near 5 volts or higher.
Action Taken When the DTC Sets
The ECC module will use a default value of approximately 200 A/D counts until the fault is cleared.
Conditions for Clearing the MIL/DTC
This fault will clear as soon as the fault goes away or has been repaired. The system will then return to normal operation. History DTCs may only be cleared by removing and restoring B+ or by using the scan tool.
Diagnostic Aids
| • | The ECC module may set class 2 lost communication DTCs when the body control module (BCM) or the vehicle control module (VCM) is being reprogrammed. After reprogramming, inspect for DTCs in the ECC module. Clear any history U DTCs, then resume diagnostics. |
| • | Visually inspect the sensor connector and harness for corrosion and damage. |
Test Description
The numbers below refer to the step numbers on the diagnostic table.
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This step inspects for a short to B+ on CKT 590.
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This step determines is the short to B+ is in CKT 590 or in the ECC module.
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This step inspects for an open in CKT 552.
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This step reads the sun load temperature sensor counts.
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This step replaces a defective sun load temperature sensor.
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This step repairs an open in CKT 552.
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This step inspects for intermittents and tests for a malfunctioning ECC module.
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This step replaces a defective ECC module.
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This step inspects for 5 volts on CKT 590.
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This step determines if the open is in CKT 590 or in the ECC module.
Step | Action | Value(s) | Yes | No |
|---|---|---|---|---|
1 | Did you perform the Diagnostic System Check? | -- | Go to Step 2 | Go to Diagnostic System Check |
Is battery voltage present? | -- | Go to Step 3 | Go to Step 12 | |
Inspect for a short to B+ in CKT 590 (LT BLU/BLK). Did you find a short to B+? | -- | Go to Step 4 | Go to Step 11 | |
4 | Repair the short to B+ in CKT 590 (LT BLU/BLK). Is the repair complete? | -- | Go to Diagnostic System Check | -- |
Inspect for continuity to ground at terminal B of the sun load temperature sensor harness connector and ground. Is continuity present? | -- | Go to Step 6 | Go to Step 8 | |
Are the sun load temperature sensor counts above the specified value? | 250 counts | Go to Step 7 | Go to Step 10 | |
Replace the sun load temperature sensor. Refer to Instrument Panel Carrier Replacement . Is the replacement complete? | -- | Go to Diagnostic System Check | -- | |
Inspect for an open in CKT 552 (BLK) . Did you find an open? | -- | Go to Step 9 | Go to Step 11 | |
9 | Repair the open in CKT 552 (BLK) . Is the repair complete? | -- | Go to Diagnostic System Check | -- |
Clear any ECC module DTCs. Does the DTC reset? | -- | Go to Step 11 | Go to Intermittents and Poor Connections Diagnosis in Wiring Systems | |
Replace the ECC module. Refer to Control Assembly Replacement . Is the replacement complete? | -- | Go to Diagnostic System Check | -- | |
Measure the voltage on terminal A of sun load temperature sensor connector to ground. Is the voltage within the specified range? | 4-6 V | Go to Step 5 | Go to Step 13 | |
Inspect for an open in CKT 590 (LT BLU). Did you find an open? | -- | Go to Step 14 | Go to Step 11 | |
14 | Repair the open in CKT 590 (LT BLU). Is the repair complete? | -- | Go to Diagnostic System Check | -- |
