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Home >> Cadillac >> 2021 >> CT4 Sport, RWD >> Repair and Diagnosis >> External Pages >> Different car >> Section 338 (Lighting System - Diagnostic Information And Procedures (2 Of 2)) >> Diagnostic Information and Procedures >> Headlamp Leveling Malfunction (Automatic) >> Circuit/System Description

Circuit/System Description

WARNING: This page is about a different car, the 2022 Cadillac CT5. However, it is still accessible from the selected car via links, so may be relevant.

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 suspension control module. The vertical suspension acceleration sensors are connected to each control arm of the front and rear suspensions. 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 right headlamp leveling actuator. The right headlamp leveling actuator uses this input to move the right headlamp 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 K9 Body Control Module (BCM).