Circuit/System Description

WARNING: This page is about a different car, the 2022 Cadillac CT4. However, it is still accessible from the selected car via links, so may be relevant.

Automatic Headlamp Leveling

The automatic headlamp leveling system consist of the following components:

Body Control Module
E13LA Headlamp Assembly - Left
E13RA Headlamp Assembly - Right
M29R Leveling Actuator - Right
Suspension height sensors

The front and rear vertical suspension acceleration sensors provide the E13LA Headlamp Assembly - Left with suspension position information. Each sensor receives a 5 V reference, signal, and low reference circuits from the left headlamp assembly. The vertical suspension acceleration sensors are connected to a control arm in the front and rear suspension. As the vehicle travels, the suspension compresses and rebounds moving the vertical suspension acceleration sensors. This causes the signal output of the sensor to change. The E13LA Headlamp Assembly - Left compares the information from the vertical suspension acceleration sensors. The E13LA Headlamp Assembly - Left uses the suspension position sensor information received from the vertical body acceleration sensors to calculate the difference in vehicle pitch. Through logic the vertical headlamp position is controlled within the left headlamp assembly. The left headlamp assembly sends a voltage signal through the appropriate headlamp leveling motor control circuit to the headlamp leveling actuators. The headlamp leveling actuators use this input to move the left and right headlamps to the appropriate vertical position. If a fault is detected within the automatic headlamp leveling system, a serial data message is sent from the left headlamp assembly to the BCM.