B1611

B1611-AMBIENT LIGHT SENSOR 1 INPUT CIRCUIT HIGH





For a complete wiring diagram, refer to the Wiring Information.

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 Diagnostic Trouble Code (DTC) will set.

- When Monitored:
With the ignition on.

- Set Condition:
If the Twilight or Ambient Light Sensor input voltage is greater than 4.5 volts for period of five seconds.





Always perform the HVAC Pre-Diagnostic Troubleshooting procedure before proceeding. HVAC Pre-Diagnostic Troubleshooting Procedure.

1. CHECK IF THE DTC IS ACTIVE
1. Ignition on, engine not running.
2. Using the scan tool, read HVAC DTCs.

Is this DTC active?

Yes

- Go To 2

No

- Go To 6

2. CHECK THE (L24) AUTO HEADLAMPS SIGNAL CIRCUIT FOR A SHORT TO VOLTAGE




1. Turn the ignition off.
2. Disconnect the A/C Heater Control C1 harness connector.
3. Ignition on, engine not running.
4. 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. HVAC Verification Test.

No

- Go To 3

3. CHECK THE (L24) AUTO HEADLAMPS SIGNAL CIRCUIT FOR AN OPEN




1. Turn the ignition off to the lock position.
2. Disconnect the Sun Sensor harness connector.
3. Measure the resistance of the (L24) Auto Headlamps Signal circuit between the A/C Heater Control C1 harness connector and the Sun Sensor harness connector.

Is the resistance below 5.0 Ohms?

Yes

- Go To 4

No

- Repair the (L24) Auto Headlamps Signal circuit for an open.
- Perform the HVAC VERIFICATION TEST. HVAC Verification Test.

4. CHECK THE (G939) SUN SENSOR RETURN CIRCUIT FOR AN OPEN




1. Measure the resistance of the (G939) Sun Sensor Return circuit between the A/C Heater Control C1 harness connector and the Sun Sensor harness connector.

Is the resistance below 5.0 Ohms?

Yes

- Go To 5

No

- Repair the (G939) Sun Sensor Return circuit for an open.
- Perform the HVAC VERIFICATION TEST. HVAC Verification Test.

5. CHECK THE SUN SENSOR AND A/C HEATER CONTROL
1. Replace the Sun Sensor.
2. Perform the HVAC VERIFICATION TEST. 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. HVAC Verification Test.

No

- Test complete.

6. CHECK THE WIRING AND CONNECTORS
1. The conditions necessary to set the DTC are not present at this time.
2. Using the scan tool, check the Environmental Data to help identify the conditions in which the DTC was set.
3. 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.
4. 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. HVAC Verification Test.

No

- Test complete.