Automatic Temperature Control

B1610-Ambient Light Sensor 1 Input Circuit Low






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: With the ignition on.

• Set Condition: If the Twilight or Ambient Light Sensor input voltage is less than 0.2 of a volt 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.

• It can take up to 60 seconds or more for this DTC to mature.

• With the scan tool, read HVAC DTCs.

Is this DTC active?

Yes

• Go to Test Step 2 => [ Test Step 2 - CHECK (L24) AUTO HEADLAMPS SIGNAL CIRCUIT FOR A SHORT
TO GROUND ]

No

• Go to Test Step 4 => [ Test Step 4 - CHECK THE WIRING AND CONNECTORS ]

Test Step 2 - CHECK (L24) AUTO HEADLAMPS SIGNAL CIRCUIT FOR A SHORT TO GROUND







• Turn the ignition off to the lock position.

• Disconnect the A/C Heater Control harness connector.

• Disconnect the Sun Sensor harness connector.

• Measure the resistance between ground and he (L24) Auto Headlamps Signal circuit.

Is the resistance below 100k Ohms?

Yes

• Repair the (L24) Auto Headlamps Signal circuit for a short to ground.

• Perform the HVAC Verification Test. Refer to => Non-DTC Based Diagnostics. HVAC Verification Test

No

• Go to Test Step 3 => [ Test Step 3 - CHECK THE A/C HEATER CONTROL ]

Test Step 3 - CHECK THE 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 4 - 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.