HVAC

B210A-84-SYSTEM VOLTAGE LOW - SIGNAL BELOW ALLOWABLE RANGE

For a complete wiring diagram, refer to the Wiring Information.

Theory of Operation

The A/C Heater Module constantly monitors battery and ignition voltage as well as battery voltage derived from BUS communication to ensure proper operation. If the voltage to the controller is out of range, it could cause damage to the controller or its respective components. If the voltage of either circuit drops below or rises above a predetermined calibration a Diagnostic Trouble Code (DTC) will set.

- When Monitored:
Continuously with the ignition on.

- Set Condition:
If the system voltage or ignition voltage broadcast over the BUS is low for period of 15 seconds.





Always perform the HVAC Pre-Diagnostic Troubleshooting procedure before proceeding. Initial Inspection and Diagnostic Overview.

1. CHECK FOR BCM DTCS
1. Ignition on, engine not running.
2. With the scan tool, read DTCs.

Are there any Body Control Module (BCM) DTCs present?

Yes

- Perform the appropriate diagnostic procedure. Testing and Inspection

No

- Go To 2

2. CHECK FOR POWERTRAIN CONTROL MODULE DTCS
1. With the scan tool, read DTCs.

Are there any Powertrain Control Module (PCM) charging system DTCs present?

Yes

- Testing and Inspection Perform the appropriate diagnostic procedure.

No

- Go To 3

3. CHECK FOR HVAC DTCS
1. With the scan tool, read HVAC DTCs.

Is the DTC B210D-84-Battery Voltage Low - Signal Below Allowable Range present also?

Yes

- Perform the diagnostic procedure for DTC B210D-84-Battery Voltage Low - Signal Below Allowable Range. B210D-84

No

- Go To 4

4. CHECK IF THE DTC IS ACTIVE
1. With the scan tool, read HVAC DTCs.

NOTE: It can take up to 15 seconds or more for this DTC to mature.

Is this DTC active?

Yes

- Go To 5

No

- Go To 6

5. CHECK IF OTHER CONTROLLERS ARE REPORTING AN UNDER VOLTAGE CONDITION
1. With the scan tool, read DTCs.

Are any other controllers reporting an under voltage condition?

Yes

- Go to DTC Based Diagnostics and perform the appropriate diagnostic procedure.

No

- Replace and program the A/C Heater Module. A/C And Heater Control Module - Removal.
- Perform the HVAC VERIFICATION TEST. HVAC Verification Test.

6. CHECK THE WIRING AND CONNECTORS
1. The conditions necessary to set the DTC are not present at this time.
2. With the scan tool, check the Environmental Data to help identify the conditions in which the DTC was set.
3. Using the wiring diagrams as a guide, check all related splices and connectors for signs of water intrusion, corrosion, pushed out or bent terminals, and correct pin tension.
4. Wiggle the wiring and connectors while checking for shorted and open circuits.

Were there any problems found?

Yes

- Repair as necessary.
- Perform the HVAC VERIFICATION TEST. HVAC Verification Test.

No

- Test complete.