GM Service Manual Online
For 1990-2009 cars only

Voltage is supplied to the headlamp leveling switch with the headlamp switch in the HEAD position. Circuit 150/250 provides ground under the same conditions.

The headlamp leveling switch provides 4 headlamp leveling positions. When a position is selected a different resistance value is provided to the headlamp leveling actuators. The actuators have a motor logic internally driving a motor to move the headlamps based on the resistance it receives. Ground is provided through circuit 150 (LH) and 250 (RH) to the actuators. Power is also supplied to the actuators through circuit 10 when the headlamp switch is in the HEAD position.

The driver controls both headlamp beams with the headlamp leveling actuators which are mount under the headlamp assembly. This feature is especially useful when the vehicle carries load changes drastically because the use of a switch helps maintain a focused and level headlamp beam.