Auto Headlamp Leveling Module (AHLM)

B210A-SYSTEM VOLTAGE LOW





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

- When Monitored:
With the headlamps ON.

- Set Condition:
When the Front Control Module (FCM) sends a message to the AHLM Module that the vehicle voltage is below 10.0 volts for over 15 seconds, this code will set.





1. CHECK POWERTRAIN CONTROL MODULE (PCM) or ENGINE CONTROL MODULE (ECM) DTCs

NOTE: The most probable cause for this DTC in this module is that the charging system or battery has failed causing a low vehicle system voltage.

NOTE: Make sure the battery is fully charged and serviceable before proceeding.

1. With the scan tool, read the PCM or ECM DTCs.

Are there any Charging or Starting DTCs present?

Yes

- For gas engine applications, Testing and Inspection Perform the appropriate diagnostic procedure.

No

- Go To 2

2. TEST FOR INTERMITTENT CONDITION
1. With the scan tool, record and erase the DTCs.
2. Start the engine and run for two minutes.
3. With the scan tool, the read DTCs.

Does the scan tool display B210A-SYSTEM VOLTAGE LOW?

Yes

- Go To 3

No

- The conditions that caused this code to set are not present at this time. Using the wiring diagram/schematic as a guide, inspect the wiring and connectors.
- Perform the BODY VERIFICATION TEST. Body Verification Test.

3. CHECK THE (F921) FUSED IGNITION SWITCH OUTPUT CIRCUIT FOR HIGH RESISTANCE
1. Using the scan tool, read the Battery Voltage of the AHLM Module.
2. Using the scan tool, read the Battery Voltage of the FCM.

Is the voltage within 1.0 volt of each module?

Yes

- Replace the Headlamp Leveling Module (AHLM).
- Perform the BODY VERIFICATION TEST. Body Verification Test.

No

- Go To 4

4. CHECK THE VOLTAGE AT THE HEADLAMP LEVELING MODULE HARNESS
1. Turn the ignition off.
2. Disconnect the AHLM Harness connector.
3. Turn the ignition on.
4. Using a voltmeter, measure the voltage between the (F921) Fused Ignition Switch Output circuit and the (Z919) Ground in the AHLM harness connector.

Is the voltage within one volt of battery voltage?

No

- Repair the (F921) Fused Ignition Switch Output circuit for high resistance.
- Perform the BODY VERIFICATION TEST. Body Verification Test.

Yes

- Replace the AHLM.
- Perform the BODY VERIFICATION TEST. Body Verification Test.