DTC B1399 Loss of KDD Communications. Buick Park Avenue 1998

For 1990-2009 cars only

Makes 🢒 Buick 🢒 1998 🢒 Park Avenue 🢒 HVAC 🢒 HVAC Systems - Automatic 🢒 DTC B1399 Loss of KDD Communications

HVAC Components
Cell 68: IP Junction Block
HVAC Air Delivery/Temperature Control Schematics
Handling ESD Sensitive Parts Notice
Handling ESD Sensitive Parts Notice

Circuit Description

The A/C control assembly receives voltage signals from the heater control module. The signal voltage will vary from 5 volts (open circuit) to 0 volts (short circuit).

Conditions for Setting the DTC

•	The ignition is on.

•	The circuit is open or shorted.

Action Taken When the DTC Sets

•	Code B1399 is set.

•	The A/C control will not operate.

Conditions for Clearing the DTC

•	Use a Scan Tool .

•	A history DTC will clear after 50 consecutive ignition cycles have occurred without a malfunction.

•	Battery voltage to the body control module is interrupted.

Test Description

Perform the Body Control Module (BCM) Diagnostic System Check before continuing with the diagnosis of this DTC.

This step determines if the programmer or A/C control is malfunctioning.

This step determines whether the programmer is malfunctioning or if there is an open/short in the circuit.

Step	Action	Value(s)	Yes	No
1	Did you perform the BCM diagnostic system check?	--	Go to Step 2	Go to Diagnostic System Check - Body Control System in Body Control System
2	Ensure that the Heater and A/C control assembly harness is disconnected. Turn the ignition switch on. Measure the voltage at the Heater and A/C control assembly harness terminal B1 and terminal A8. Refer to Measuring Voltage in Wiring Systems. Does the voltage measure near the specified value?	4.5 V	Go to Step 3	Go to Step 7
3	Measure the voltage at the heater and A/C control assembly connector terminal B1 and terminal A8. Refer to Measuring Voltage in Wiring Systems. Does the voltage measure near the specified value?	3.5 V	Go to Step 6	Go to Step 4
4	Backprobe the Heater and A/C control assembly harness connector to measure the voltage at terminal C13 and terminal D16. Refer to Probing Electrical Connectors in Wiring Systems. Does the voltage measure near the specified value?	1.0 V	Go to Step 8	Go to Step 5
5	Inspect the heater and A/C programmer harness terminal for proper contact. If the terminal contact is OK, replace the heater and A/C programmer. Refer to Programmer Replacement . Did you replace the heater and A/C programmer?	--	Go to Diagnostic System Check - Body Control System in Body Control System	--
6	Inspect the Heater and A/C control assembly terminals for proper contact. If the terminal contact is OK, replace the Heater and A/C control assembly. Refer to Control Assembly Replacement . Did you replace the Heater and A/C control assembly?	--	Go to Diagnostic System Check - Body Control System in Body Control System	--
7	Backprobe the heater and A/C programmer harness connector at terminal C12 and terminal D16. Refer to Probing Electrical Connectors in Wiring Systems. Does the voltage measure near the specified value?	4.5V	Go to Step 9	Go to Step 5
8	Repair the open in CKT 1180 (PPL). Refer to Wiring Repairs in Wiring Systems. Is the repair complete?	--	Go to Diagnostic System Check - Body Control System in Body Control System	--
9	Repair the open in CKT 1181 (LT BLU). Refer to Wiring Repairs in Wiring Systems. Is the repair complete?	--	Go to Diagnostic System Check - Body Control System in Body Control System	--