GM Service Manual Online
For 1990-2009 cars only
Makes 🢒 Cadillac 🢒 2006 🢒 Escalade ESV 🢒 HVAC 🢒 HVAC Systems - Automatic 🢒 DTC B0169

Circuit Description

The auxiliary inside air temperature sensor assembly allows the auxiliary HVAC control module to monitor the temperature of the air inside the passenger compartment. The module applies 5 volts to the internal input resistor that is connected to the signal circuit of the air temperature sensor. The module provides ground to the air temperature sensor through the low reference circuit. The auxiliary HVAC control module monitors the voltage drop across the air temperature sensor and uses the input for automatic control calculations. When the air temperature is cold, the resistance of the sensor is high and the voltage signal is high. When the air temperature is hot, the resistances of the sensor is low and the voltage signal is low.

DTC Descriptor

This diagnostic procedure supports the following DTC:

DTC B0169 ?

Conditions for Running the DTC
    • Battery voltage to the auxiliary HVAC control module is greater than 8.7 volts and less than 16.5 volts.
    • The ignition is turned ON.

Conditions for Setting the DTC

The auxiliary HVAC control module determines that the voltage applied to the input for the auxiliary inside air temperature sensor is less than 0.09 volt or greater than 4.9 volts.

Action Taken When the DTC Sets

The auxiliary HVAC control module use a default value of 128 counts for the Inside Air Temp. Sensor parameter. This value will not be displayed on the scan tool. The value displayed on the scan tool is the actual value of the signal circuit.

Conditions for Clearing the DTC
    • The DTC will become history if the auxiliary HVAC control module no longer detects the condition that set the DTC.
    • The history DTC will clear after 100 fault-free ignition cycles.
    • The DTC can be cleared with a scan tool.

Test Description

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

  1. This step verifies that the temperature displayed is not within the calibrated range.

    2.

  2. This step tests for the proper operation of the circuit in the high voltage range.

    3.

  3. This step 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

No

Schematic Reference: HVAC Schematics

Connector End View Reference: HVAC Connector End Views

1

Did you perform the Diagnostic System Check - Vehicle?

--

Go to Step 2

Go to Diagnostic System Check - Vehicle in Vehicle DTC Information

2

  1. Install a scan tool.
  2. Turn ON the ignition, with the engine OFF.
  3. With a scan tool, observe the Inside Air Temp. Sensor parameter in the Rear Aux. Climate Module data list.

Does the scan tool indicate that the Inside Air Temp. Sensor parameter is within the specified range?

5-250 Counts

Go to Testing for Intermittent Conditions and Poor Connections in Wiring Systems

Go to Step 3

3

  1. Turn OFF the ignition.
  2. Disconnect the auxiliary inside air temperature sensor assembly.
  3. Turn ON the ignition, with the engine OFF.
  4. With a scan tool, observe the Inside Air Temp. Sensor data parameter.

Does the scan tool indicate that the Inside Air Temp. Sensor data parameter is greater than the specified value?

250 Counts

Go to Step 4

Go to Step 5

4

  1. Turn OFF the ignition.
  2. Connect a 3-amp fused jumper wire between the signal circuit of the auxiliary inside air temperature sensor assembly and the low reference circuit of the auxiliary inside air temperature sensor assembly.
  3. Turn ON the ignition, with the engine OFF.
  4. With a scan tool, observe the Inside Air Temp. Sensor data parameter.

Does the scan tool indicate that the Inside Air Temp. Sensor data parameter is less than the specified value?

5 Counts

Go to Step 8

Go to Step 6

5

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

Did you find and correct the condition?

--

Go to Step 12

Go to Step 9

6

Test the signal circuit of the auxiliary inside air temperature sensor assembly for a short to voltage, a high resistance, or an open. Refer to Circuit Testing and Wiring Repairs in Wiring Systems.

Did you find and correct the condition?

--

Go to Step 12

Go to Step 7

7

Test the low reference circuit of the auxiliary inside air temperature sensor assembly for a high resistance or an open. Refer to Circuit Testing and Wiring Repairs in Wiring Systems.

Did you find and correct the condition?

--

Go to Step 12

Go to Step 9

8

Inspect for poor connections at the harness connector of the auxiliary inside air temperature sensor assembly. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs in Wiring Systems.

Did you find and correct the condition?

--

Go to Step 12

Go to Step 10

9

Inspect for poor connections at the harness connector of the auxiliary HVAC control module. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs in Wiring Systems.

Did you find and correct the condition?

--

Go to Step 12

Go to Step 11

10

Replace the auxiliary inside air temperature sensor assembly. Refer to Auxiliary Inside Air Temperature Sensor Assembly Replacement .

Did you complete the replacement?

--

Go to Step 12

--

11

Replace the auxiliary HVAC control module. Refer to Control Module References in Computer/Integrating Systems for replacement, setup, and programming.

Did you complete the replacement?

--

Go to Step 12

--

12
  1. Use the scan tool in order to clear the DTCs.
  2. Operate the vehicle within the Conditions for Running the DTC as specified in the supporting text.

Does the DTC reset?

--

Go to Step 2

System OK