Automatic Temperature Control
B1611-Ambient Light Sensor 1 Input Circuit High
For a complete wiring diagram, refer to.
Theory of Operation
The HVAC A/C Heater Control uses a variety of sensors to adjust HVAC operation to obtain optimal performance. These sensors are continuously monitored by the A/C Heater Control to assure that they are in range. If those sensors fall out of predetermined ranges a DTC will set.
• When Monitored: Continuously with the ignition on.
• Set Condition: If the Twilight or Ambient Light Sensor input voltage is greater than 4.66 volts for period of 60 seconds.
Always perform the HVAC Pre-Diagnostic Troubleshooting procedure before proceeding. Refer to => Non-DTC Based
Diagnostics. HVAC Pre-Diagnostic Troubleshooting Procedure
Test Step 1 - CHECK IF THE DTC IS ACTIVE
• Ignition on, engine not running.
• With the scan tool, read HVAC DTCs.
• It can take up to 60 seconds or more for this DTC to mature.
Is this DTC active?
Yes
• Go to Test Step 2 => [ Test Step 2 - CHECK (L24) AUTO HEADLAMPS SIGNAL CIRCUIT FOR A SHORT
TO VOLTAGE ]
No
• Go to Test Step 6 => [ Test Step 6 - CHECK THE WIRING AND CONNECTORS ]
Test Step 2 - CHECK (L24) AUTO HEADLAMPS SIGNAL CIRCUIT FOR A SHORT TO VOLTAGE
• Turn the ignition off to the lock position.
• Disconnect the A/C Heater Control harness connector.
• Disconnect the Sun Sensor harness connector.
• Ignition on, engine not running.
• Measure the voltage of the (L24) Auto Headlamps Signal circuit.
Is there any voltage present?
Yes
• Repair the (L24) Auto Headlamps Signal circuit for a short to voltage.
• Perform the HVAC Verification Test. Refer to => Non-DTC Based Diagnostics. HVAC Verification Test
No
• Go to Test Step 3 => [ Test Step 3 - CHECK (L24) AUTO HEADLAMPS SIGNAL CIRCUIT FOR AN OPEN ]
Test Step 3 - CHECK (L24) AUTO HEADLAMPS SIGNAL CIRCUIT FOR AN OPEN
• Turn the ignition off to the lock position.
• Measure the resistance of the (L24) Auto Headlamps Signal circuit between the A/C Heater Control harness connector and the Sun Sensor harness connector.
Is the resistance below 1.0 Ohm?
Yes
• Go to Test Step 4 => [ Test Step 4 - CHECK (C121) SENSOR GROUND CIRCUIT FOR AN OPEN ]
No
• Repair the (L24) Auto Headlamps Signal circuit for an open or high resistance.
• Perform the HVAC Verification Test. Refer to => Non-DTC Based Diagnostics. HVAC Verification Test
Test Step 4 - CHECK (C121) SENSOR GROUND CIRCUIT FOR AN OPEN
• Measure the resistance of the (C121) Sensor Ground circuit between the A/C Heater Control harness connector and the Sun Sensor harness connector.
Is the resistance below 1.0 Ohm?
Yes
• Go to Test Step 5 => [ Test Step 5 - CHECK THE SUN SENSOR AND A/C HEATER CONTROL ]
No
• Repair the (C121) Sensor Ground circuit for an open or high resistance.
• Perform the HVAC Verification Test. Refer to => Non-DTC Based Diagnostics. HVAC Verification Test
Test Step 5 - CHECK THE SUN SENSOR AND A/C HEATER CONTROL
• Replace the Sun Sensor.
• Perform the HVAC Verification Test. Refer to => Non-DTC Based Diagnostics. HVAC Verification Test
Did this DTC reset while performing the HVAC Verification Test?
Yes
• Replace and program the A/C Heater Control.
• Perform the HVAC Verification Test. Refer to => Non-DTC Based Diagnostics. HVAC Verification Test
No
• Test complete.
Test Step 6 - CHECK THE WIRING AND CONNECTORS
• The conditions necessary to set the DTC are not present at this time.
• With the scan tool, check the Environmental Data to help identify the conditions in which the DTC was set.
• Using the wiring diagrams as a guide, check all related splices and connectors for signs of water intrusion, corrosion, pushed out or bent terminals, and correct pin tension.
• Wiggle the wiring and connectors while checking for shorted and open circuits.
Were there any problems found?
Yes
• Repair as necessary.
• Perform the HVAC Verification Test. Refer to => Non-DTC Based Diagnostics. HVAC Verification Test
No
• Test complete.