Circuit Description
The instrument panel module (IPM) communicates with the heater and A/C control via the keyboard display driver (KDD) data bus. This communication link is only used by the IPM and the heater and A/C control.
Conditions for Running the DTC
The ignition is turned ON.
Conditions for Setting the DTC
| • | There is a loss of communications between the IPM and the heater and A/C control. |
| • | The above conditions are present for 3 seconds. |
Action Taken When the DTC Sets
The heater and A/C system will be disabled.
Conditions for Clearing the DTC
| • | The DTC will become history if the IPM no longer detects a failure. |
| • | The history DTC will clear after 50 fault free ignition cycles. |
| • | 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.
Step | Action | Value(s) | Yes | No |
|---|---|---|---|---|
1 | Did you perform the HVAC Diagnostic System Check? | -- | Go to Step 2 | Go to Diagnostic System Check |
2 |
Are all of the visual indicators illuminated and is the audible indicator ON? | -- | Go to Step 7 | Go to Step 3 |
3 |
Is the display of the heater and A/C control blank? | -- | Go to Step 5 | Go to Step 4 |
Does the heater and A/C control display only °C°F? | -- | Go to Step 8 | Go to Testing for Intermittent Conditions and Poor Connections | |
5 |
Notice: Refer to Test Probe Notice in the Preface section.
Does the test lamp illuminate? | -- | Go to Step 6 | Go to Step 10 |
6 |
Notice: Refer to Test Probe Notice in the Preface section. Probe the battery positive voltage circuit of the heater and A/C control with a test lamp that is connected to the logic ground circuit of the heater and A/C control. Does the test lamp illuminate? | -- | Go to Step 15 | Go to Step 11 |
7 |
Notice: Refer to Test Probe Notice in the Preface section.
Does the voltage measure near the specified value? | 1 Vdc | Go to Step 15 | Go to Step 12 |
8 |
Notice: Refer to Test Probe Notice in the Preface section.
Does the voltage measure near the specified value? | 1 Vdc | Go to Step 9 | Go to Step 13 |
9 |
Notice: Refer to Test Probe Notice in the Preface section. Measure the frequency from the KDD clock circuit to a good ground. Does the frequency measure near the specified value? | 930 Hz | Go to Step 15 | Go to Step 14 |
10 |
Notice: Refer to Test Probe Notice in the Preface section. Repair the battery positive voltage circuit of the heater and A/C control for a short to ground, 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 19 | -- |
11 |
Notice: Refer to Test Probe Notice in the Preface section. Repair the logic ground circuit of the heater and A/C control 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 19 | -- |
12 |
Notice: Refer to Test Probe Notice in the Preface section. Test the KDD data circuit for a short to voltage or an open. Refer to Circuit Testing and Wiring Repairs in Wiring Systems. Did you find and correct the condition? | -- | Go to Step 19 | Go to Step 16 |
13 |
Notice: Refer to Test Probe Notice in the Preface section. Test the KDD data circuit 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 19 | Go to Step 14 |
14 |
Notice: Refer to Test Probe Notice in the Preface section. Test the KDD clock circuit for a short to voltage, a short to ground, or an open. Refer to Circuit Testing and Wiring Repairs in Wiring Systems. Did you find and correct the condition? | -- | Go to Step 19 | Go to Step 16 |
15 | Inspect for poor connections at the harness connector of the heater and A/C control. 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 19 | Go to Step 17 |
16 | Inspect for poor connections at the harness connector of the IPM. 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 19 | Go to Step 18 |
17 | Replace the heater and A/C control. Refer to Control Assembly Replacement . Did you complete the replacement? | -- | Go to Step 19 | -- |
18 | Replace the IPM. Refer to Instrument Panel Module Replacement in Body Control System. Did you complete the replacement? | -- | Go to Step 19 | -- |
19 |
Does the DTC reset? | -- | Go to Step 2 | System OK |
