Operation CHARM: Car repair manuals for everyone.

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.