DTC B1399 Loss of KDD Communications. Buick Park Avenue 1999

For 1990-2009 cars only

Makes 🢒 Buick 🢒 1999 🢒 Park Avenue 🢒 DTC 🢒 DTC B1399 Loss of KDD Communications

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HVAC Air Delivery/Temperature Control Schematics
Cell 68: IP Fuse Block
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

•	Using a Scan Tool .

•	A history DTC will clear after 50 fault free ignition cycles.

•	HCM battery voltage is interrupted.

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

Determines if the programmer or A/C control is malfunctioning.

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
2	Ensure that the heater and A/C control assembly harness is disconnected. Turn the ignition switch ON. Measure the voltage at heater and A/C control assembly harness terminals B1 and A8. Refer to Measuring Voltage in Wiring Systems. Does the voltage equal the specified value?	4.5V	Go to Step 3	Go to Step 7
3	Measure the voltage at heater and A/C control assembly connector terminals B1 and A8. Refer to Measuring Voltage in Wiring Systems. Does the voltage equal the specified value?	3.5V	Go to Step 6	Go to Step 4
4	Backprobe the heater and A/C control assembly harness connector to measure the voltage at terminals C13 and D16. Refer to Probing Electrical Connectors and Measuring Voltage in Wiring Systems. Does the voltage equal the specified value?	1.0V	Go to Step 8	Go to Step 5
5	Inspect the HCM harness terminal for proper contact. Refer to Intermittents and Poor Connections Diagnosis in Wiring Systems. 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	--
6	Inspect the heater and A/C control assembly terminals for proper contact. Refer to Intermittents and Poor Connections Diagnosis in Wiring Systems. 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	--
7	Backprobe the HCM harness connector at terminal C12 and terminal D16. Refer to Probing Electrical Connectors and Measuring Voltage in Wiring Systems. Does the voltage equal 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	--
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	--