Circuit Description
The HVAC control module monitors the air temperature in the floor discharge duct via a lower air temperature sensor. When the air is cold, the sensor resistance and the signal voltage are high. When the air is warm, the sensor resistance and the signal voltage are low.
Conditions for Running the DTC
The ignition is turned ON.
Conditions for Setting the DTC
The HVAC control module detects the signal circuit is less than 5 Counts (0.09 V) or greater than 250 Counts (4.90 V) .
Action Taken When the DTC Sets
A default value will be used for the sensor data by the HVAC control module. The actual value of the sensor will be displayed on the scan tool.
Conditions for Clearing the DTC
| • | The DTC will become history if the HVAC control module no longer detects a condition. |
| • | The history DTC clears after 50 fault free ignition cycles. |
| • | The DTC can be cleared with a scan tool. |
Diagnostic Aids
If the condition is not present, refer to Testing for Intermittent Conditions and Poor Connections in Wiring Systems.
Test Description
The number(s) below refer to the step number(s) 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 | No |
|---|---|---|---|---|
Schematic Reference: HVAC Schematics | ||||
1 | Did you perform the HVAC Diagnostic System Check? | -- | Go to Step 2 | |
2 |
Does the scan tool indicate that the Lower Outlet Temp. parameter is within the specified range? | 5-250 Counts | Go to Diagnostic Aids | Go to Step 3 |
Does the scan tool indicate that the Lower Outlet Temp. parameter is greater than the specified value? | 250 Counts | Go to Step 4 | Go to Step 5 | |
Does the scan tool indicate that the Lower Outlet Temp. parameter is less than the specified value? | 5 Counts | Go to Step 8 | Go to Step 6 | |
5 | Test the signal circuit of the lower air temperature sensor 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 lower air temperature sensor 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 lower air temperature sensor 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 lower air temperature sensor. 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 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 lower air temperature sensor. Refer to Air Temperature Sensor Replacement - Lower . Did you complete the replacement? | -- | Go to Step 12 | -- |
11 |
Important: Perform the recalibration procedure for the HVAC control module. Replace the HVAC control module. Refer to HVAC Control Module Replacement . Did you complete the replacement? | -- | Go to Step 12 | -- |
12 |
Does the DTC reset? | -- | Go to Step 2 | System OK |
