Circuit Description
The sunload sensor assembly is a light sensitive photocell. The HVAC control module determines the ambient light based on the voltage from the sunload sensor assembly. The HVAC control module controls the headlamp automatic on/off and delayed off functions.
DTC Descriptor
This diagnostic procedure supports the following DTC:
DTC B2648 Ambient Light Sensor Circuit High
Conditions for Running the DTC
| • | The enable flag is set to enable. |
| • | DTC B1327 is not current. |
| • | The HVAC control module is powered. |
Conditions for Setting the DTC
| • | The sunload sensor assembly voltage is greater than 4.8 volts. |
| • | The above condition is present for greater than 2 seconds. |
Action Taken When the DTC Sets
| • | The HVAC control module sets the variable ambient light status to status set to DARK. |
| • | The HVAC control module sets a DTC. |
Conditions for Clearing the DTC
The HVAC control module does not detect a voltage greater than the predetermined value during the diagnostic self test.
Test Description
The numbers below refer to the step numbers on the diagnostic table.
-
This step tests for the proper operation of the circuit in the high voltage range.
-
This step tests for the proper operation of the circuit in the low voltage range. If the fuse in the jumper opens when you perform this test, the sunload sensor assembly signal circuit is shorted to battery positive voltage.
Step | Action | Value(s) | Yes | No |
|---|---|---|---|---|
Schematic Reference: Headlights/Daytime Running Lights (DRL) Schematics Connector End View Reference: Computer/Integrating Systems Connector End Views in Computer/Integrating Systems or Lighting Systems Connector End Views | ||||
1 | Did you perform the Diagnostic System Check - Vehicle? | -- | Go to Step 2 | Go to Diagnostic System Check - Vehicle in Vehicle DTC Information |
2 |
Does the scan tool indicate that the Ambient Light Sensor parameter is within the specified range? | 0.2-4.8 V | Go to Testing for Intermittent Conditions and Poor Connections in Wiring Systems | Go to Step 3 |
Does the scan tool indicate that the Ambient Light Sensor data parameter is greater than the specified value? | 4.8 V | Go to Step 4 | Go to Step 5 | |
Does the scan tool indicate that the Ambient Light Sensor data parameter is less than the specified value? | 0.2 V | Go to Step 8 | Go to Step 6 | |
5 | Test the ambient light sensor signal circuit for a short to ground. Refer to Circuit Testing and Wiring Repairs in Wiring Systems. Did you find and correct the condition? | -- | Go to Step 12 | Go to Step 9 |
6 | Test the ambient light sensor signal circuit for an open or a short to battery positive voltage. Refer to Circuit Testing and Wiring Repairs in Wiring Systems. Did you find and correct the condition? | -- | Go to Step 12 | Go to Step 7 |
7 | Test the low reference circuit for a high resistance or an open. Refer to Circuit Testing and Wiring Repairs in Wiring Systems. Did you find and correct the condition? | -- | Go to Step 12 | Go to Step 9 |
8 | Inspect for poor connections at the harness connector of the sunload sensor assembly. 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 12 | Go to Step 10 |
9 | Inspect for poor connections at the harness connector of the CCP. 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 12 | Go to Step 11 |
10 | Replace the sunload sensor assembly. Refer to Sunload and Twilight Sentinel Sensor Replacement in Instrument Panel, Gages, and Console. Did you complete the replacement? | -- | Go to Step 12 | -- |
11 | Replace the CCP. Refer to Control Module References in Computer/Integrating Systems for replacement, setup, and programming. Did you complete the replacement? | -- | Go to Step 12 | -- |
12 |
Does the DTC reset? | -- | Go to Step 2 | System OK |
