DTC B0160, B0161, B0165, or B0166. Chevrolet Blazer - 4WD

For 1990-2009 cars only

Makes 🢒 Chevrolet 🢒 2003 🢒 Blazer - 4WD - RHD 🢒 DTC 🢒 DTC B0160, B0161, B0165, or B0166

Circuit Description

The following DTCs are for the ambient air temperature sensor and for the inside air temperature sensor assembly:

•	B0160 and B0161 are for the ambient air temperature sensor.

•	B0165 and B0166 are for the inside air temperature sensor assembly.

The ambient air temperature sensor allows the HVAC control module to monitor the temperature of the air surrounding the front of the vehicle. The inside air temperature sensor assembly allows the HVAC control module to monitor the temperature of the air inside the passenger compartment. The module applies 5 volts to internal input resistors that are connected to the signal circuits of the air temperature sensors. The module provides ground to the air temperature sensors through the low reference circuits. The HVAC control module monitors the voltage drops across the air temperature sensors and uses the inputs for automatic control calculations. The HVAC control module also uses the ambient air temperature input to calculate the value of the ambient air temperature display. When the air temperatures are cold, the resistances of the sensors are high and the voltage signals are high. When the air temperatures are hot, the resistances of the sensors are low and the voltage signals are low.

Conditions for Running the DTC

The ignition is turned ON.

Conditions for Setting the DTC

The HVAC control module determines that the voltage applied to the input for the air temperature sensor is less than 0.09 V, for B0160 and B0165, or greater than 4.9 V, for B0161 and B0166.

Action Taken When the DTC Sets

The HVAC control module uses a default temperature sensor value until the fault is cleared. The actual value will be displayed on the scan tool.

Conditions for Clearing the DTC

•	The DTC becomes history when the HVAC control module no longer detects a failure.

•	The history DTC clears after 50 fault free ignition cycles.

•	The DTC can be cleared with a scan tool.

Diagnostic Aids

•	Visually inspect the sensor connector and harness for corrosion and damage. The resistance value of the sensor must be between 47-101,000 ohms. If the resistance is not within the specified value, replace the sensor.

•	Insure ambient air temperature sensor shield is in place. If this is not in place it could lead to excessive air flow across sensor and give incorrect reading to HVAC control module.

•	Insure inside air temperature sensor assembly is in place and secure. Insure no restrictions or debris around the air temperature sensor this will give incorrect reading to HVAC control module.

•	If condition is not present, refer to Testing for Intermittent Conditions and Poor Connections in Wiring Systems.

Test Description

The numbers below refer to the step numbers on the diagnostic table.

Tests for the proper operation of the circuit in the high voltage range.

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 signal circuit is shorted to voltage.

Step

Action

Value(s)

Yes

Schematic Reference: HVAC Schematics

Connector End View Reference: HVAC Connector End Views

Did you perform the HVAC Diagnostic System Check?

Go to Step 2

Go to Diagnostic System Check - HVAC Systems - Automatic

Install a scan tool.
Turn ON the ignition, with the engine OFF.
With a scan tool, observe the appropriate Air Temperature parameter in the Heating and Air Conditioning data list.

Does the scan tool indicate that the Air Temperature parameter is within the specified range?

-40 to +80°C (-40 to +176°F)

Go to Diagnostic Aids

Go to Step 3

Turn OFF the ignition.
Disconnect the air temperature sensor.
Turn ON the ignition, with the engine OFF.
With a scan tool, observe the appropriate Air Temperature data parameter.

Does the scan tool indicate that the Air Temperature data parameter is greater than the specified value?

-53°C (-65°F)

Go to Step 4

Go to Step 5

Turn OFF the ignition.
Connect a 3 amp fused jumper wire between the signal circuit of the air temperature sensor and the low reference circuit of the air temperature sensor.
Turn ON the ignition, with the engine OFF.
With a scan tool, observe the appropriate Air Temperature data parameter.

Does the scan tool indicate that the Air Temperature data parameter is less than the specified value?

125°C (275°F)

Go to Step 8

Go to Step 6

Test the appropriate signal circuit of the air temperature sensor for a short to ground. Refer to Circuit Testing and Wiring Repairs in Wiring Systems.