Pinpoint Test J: The HVAC Module Does Not Respond To The Scan Tool

Communications Network

Pinpoint Test J: The HVAC Module Does Not Respond To The Scan Tool


Normal Operation

The HVAC module communicates with the scan tool through the Medium Speed Controller Area Network (MS-CAN).

This pinpoint test is intended to diagnose the following:

- Fuse

- Wiring, terminals or connectors

- HVAC module

PINPOINT TEST J : THE HVAC MODULE DOES NOT RESPOND TO THE SCAN TOOL

NOTICE: Use the correct probe adapter(s) when making measurements. Failure to use the correct probe adapter(s) may damage the connector.

NOTE: Failure to disconnect the battery when instructed will result in false resistance readings.

J1 CHECK THE HVAC MODULE VOLTAGE SUPPLY CIRCUITS FOR AN OPEN

- Ignition OFF.

- Disconnect: HVAC Module C228.

- Ignition ON.

- Measure the voltage between the HVAC module C228-32, circuit SBP46 (BN/RD), harness side and ground.





Is the voltage greater than 10 volts?

Yes
GO to J2.

No
VERIFY the Body Control Module (BCM) fuse 46 (10A) is OK. If OK, REPAIR the circuit in question. If not OK, REFER to the Wiring Diagrams to identify the possible causes of the circuit short. CLEAR the DTCs. REPEAT the network test with the scan tool. [1][2]Diagrams By Number

J2 CHECK THE HVAC MODULE GROUND CIRCUIT FOR AN OPEN

- Ignition OFF.

- Disconnect: Negative Battery Cable.

- Measure the resistance between the HVAC module C228-10 circuit GD184 (BK/GY or BK/YE), harness side and ground.





Is the resistance less than 5 ohms?

Yes
GO to J3.

No
REPAIR the circuit. CLEAR the DTCs. REPEAT the network test with the scan tool.

J3 CHECK THE MS-CAN (Medium Speed Controller Area Network) CIRCUITS BETWEEN THE HVAC MODULE AND THE DLC (Data Link Connector) FOR AN OPEN

- Measure the resistance between the HVAC module C228-12 circuit VDB06 (GY/OG), harness side and the Data Link Connector (DLC) C251-3, circuit VDB06 (GY/OG), harness side.





- Measure the resistance between the HVAC module C228-13 circuit VDB07 (VT/OG), and the DLC (Data Link Connector) C251-11, circuit VDB07 (VT/OG), harness side.





Are the resistances less than 5 ohms?

Yes
CONNECT the negative battery cable. GO to J4.

No
REPAIR the circuit in question. CLEAR the DTCs. REPEAT the network test with the scan tool.

J4 CHECK FOR CORRECT HVAC MODULE OPERATION

- Disconnect all the HVAC module connectors.

- Check for:
- corrosion

- damaged pins

- pushed-out pins


- Connect all the HVAC module connectors and make sure they seat correctly.

- Operate the system and verify the concern is still present.

Is the concern still present?

Yes
INSTALL a new HVAC module. CLEAR the DTCs. REPEAT the network test with the scan tool.

No
The system is operating correctly at this time. The concern may have been caused by a loose or corroded connector.