For 1990-2009 cars

### Circuit Description

In-car sensor or Front PCAT Sensor allow the HVAC control module to monitor the temperature in the car.

### DTC Descriptors

This diagnostic procedure supports the following DTC:

DTC B0163 Front PCAT Sensor Input Voltage

### Conditions for Running the DTC

Ignition is ON.

### Conditions for Setting the DTC

• | The HVAC control module determines that the value of the air temperature parameter is less than 0.27V or greater than 4.64V.

• | The HVAC control module detects a short to battery positive voltage in the In-car sensor or PCAT sensor.

• | The HVAC control module detects that the In-car sensor or PCAT sensor control circuit is open.

### Action Taken When the DTC Sets

The In-car sensor or PCAT sensor value setting in 25 degrees.

### Conditions for Clearing the DTC

• | The DTC will become history if the HVAC control module no longer detects a fault.

• | Ignition is ON or OFF.

• | The DTC can be cleared with a scan tool.

### Test Description

The number(s) below refer to the step number(s) on the diagnostic table.

1. Tests resistance of the In-car sensor or PCAT sensor.

2. Tests the voltage of the In-car sensor or PCAT sensor from the HVAC control module.

Step | Action | Value(s) | Yes | No
--- | --- | --- | --- | ---
1 | Did you perform the Diagnostic System Check - Vehicle? | -- | Go to Step 2 | Go to Diagnostic System Check - Vehicle
2 |

1. Install a scan tool.
2. Turn ON the ignition, with the engine OFF.
3. With a scan tool, observe the In-car sensor value in the Heating and Air Conditioning data list.

Does the scan tool indicate that the In-car parameter is within the specified range?

0.27-4.64V

Go to Step 8

Go to Step 3

3 |

1. Turn OFF the ignition.
2. Disconnect the In-car sensor.
3. Turn ON the ignition, with the engine OFF.
4. With a scan tool, observe the In-car sensor data parameter.

Does the scan tool indicate that the In-car data parameter is greater than the specified value?

4.64V

Go to Step 4

Go to Step 5

4 |

1. Turn OFF the ignition.
2. Connect a fused jumper wire between the signal circuit of the In-car sensor and the low reference circuit of the In-car sensor.
3. Turn ON the ignition, with the engine OFF.
4. With a scan tool, observe the In-car sensor parameter.

Does the scan tool indicate that the Duct Actual data parameter is less than the specified value?

0.27V

Go to Step 8

Go to Step 6

5 | Test the signal circuit of the In-car sensor for a short to ground. Did you find and correct the condition? | -- | Go to Step 12 | Go to Step 9
6 | Test the signal circuit of the In-car sensor for a short to voltage, a high resistance, or an open. Did you find and correct the condition? | -- | Go to Step 12 | Go to Step 7
7 | Test the low reference circuit of the In-car sensor for a high resistance or an open. 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 In-car sensor. 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 HVAC control module. Did you find and correct the condition? | -- | Go to Step 12 | Go to Step 11
10 | Replace the In-car sensor. Did you complete the replacement? | -- | Go to Step 12 | --
11 | Replace the HVAC control module. 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