Circuit Description
The instrument panel integration module (IPM) communicates with the HVAC control module through the HVAC control module data signal circuit and the HVAC control module clock signal circuit. This communication link is only used by the IPM and the HVAC control module.
DTC Descriptor
This diagnostic procedure supports the following DTC:
DTC B1399 Loss of KDD Communications
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 HVAC control module. |
| • | 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 numbers below refer to the step numbers on the diagnostic table.
Step | Action | Values | 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 |
Are all of the visual indicators illuminated and is the audible indicator ON? | -- | Go to Step 7 | Go to Step 3 |
3 | Observe the display of the HVAC control module. Is the display of the HVAC control module blank? | -- | Go to Step 5 | Go to Step 4 |
Observe the display of the HVAC control module. Does the HVAC control module display only °C °F? | -- | Go to Step 9 | Go to Testing for Intermittent Conditions and Poor Connections in Wiring Systems | |
5 |
Does the test lamp illuminate? | -- | Go to Step 6 | Go to Step 10 |
6 | Connect a test lamp between the ignition 3 voltage circuit and the ground circuit of the HVAC control module. Does the test lamp illuminate? | -- | Go to Step 8 | Go to Step 11 |
7 |
Does the voltage measure near the specified value? | 3.9-4.3 V | Go to Step 15 | Go to Step 12 |
8 |
Does the voltage measure near the specified value? | 4.3 V | Go to Step 9 | Go to Step 13 |
9 | Measure the frequency between the HVAC control module clock signal circuit of the HVAC control module and a good ground. Does the frequency measure near the specified value? | 685 Hz | Go to Step 15 | Go to Step 14 |
10 | Test the ignition 3 voltage circuit of the HVAC control module 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 | Test the ground circuit of the HVAC control module 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 | Test the HVAC control module data signal 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 | Test the HVAC control module data signal 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 14 |
14 | Test the HVAC control module clock signal 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 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 19 | Go to Step 17 |
16 | Inspect for poor connections at the harness connector of the instrument panel integration module (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 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 19 | -- |
18 | Replace the IPM. Refer to Control Module References in Computer/Integrating Systems for replacement, setup, and programming. Did you complete the replacement? | -- | Go to Step 19 | -- |
19 |
Does the DTC reset? | -- | Go to Step 2 | System OK |
