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Automatic High Beams

WARNING: This page is about a different car, the 2019 RAM 3500 HD and 2019 RAM 2500 HD. However, it is still accessible from the selected car via links, so may be relevant.
AUTOMATIC HIGH BEAMS

Refer to FEATURES INDEX .

The BCM uses internal configuration parameters to determine if the vehicle is equipped with the auto high beam feature and if the auto high beam feature is using a CRVMM or a DASM for operation.

The headlamp switch needs to be in the AUTO position, the high beam select lever needs to be ON and the auto high beam feature enabled in the radio for the system to operate.

- CRVMM equipped 

When enabling conditions are met, the CRVMM sends a LIN message request for high beam activation to the BCM. The BCM receives this message and then a CAN-C bus message indicating that high beams system is now active and ready for operation. When the IPC receives this bus message, the IPC displays an auto high beam enabled message to the driver. The CRVMM will then monitor vehicle speed (the vehicle must be travelling at speeds above 24 kmh/15 mph), ambient light levels, and light from oncoming traffic to determine when to activate the high beams. When the CRVMM determines to enable the auto high beam headlamps, it will send a LIN signal to the BCM indicating 100% duty cycle. The BCM interprets this LIN message as a high beam request. Conversely, a duty cycle request of 0% will command the BCM to turn off the high beam headlamps.

- DASM equipped 

The DASM acquires the following CAN-C bus messages for system use:

SIGNAL NAME SIGNAL PURPOSE
CBC_PT1.HIBEAM_ON High Beam Status
CBC_PT1.FT_WPR_NOT_PRK Wiper Not Parked Status
ESP_A8.VEH_SPEED Vehicle Speed
ESP_A4.VehYawRate_Offset Yaw Rate Offset
ESP_A4.VehYawRate_Raw Yaw Rate Raw
NET_CFG_PT.NetCfg_DASM DASM Network Configuration Status

The DASM will send the following CAN-C message to the BCM:

SIGNAL NAME SIGNAL PURPOSE
DAS_A6.IRCM_AHB_On High beam ON command (High Beams ON = 1, High Beams OFF = 0)

When lighting conditions are met and no objects are detected, the DASM sends a CAN-C bus message to the BCM to enable the auto high beam system. The BCM will check the following conditions to enable the auto high beam feature:

Once all enabling conditions are met and the BCM has received both the CAN-C DASM auto high beam enabled request and a CAN-C vehicle speed signal that indicates that the vehicle has achieved speeds above 24 kmh (15 mph), the BCM sets a CAN-C message that the auto high beam feature is now enabled and active.

The DASM can then send a CAN-C message to the BCM requesting auto high beams ON or OFF. The BCM receives either signal from the DASM and will either command the high beam headlamps ON or OFF as requested.