EXTERIOR LAMPS - Headlamp Levelling

EXTERIOR LAMPS - Headlamp Levelling

DESCRIPTION

To prevent dazzling oncoming drivers, the headlamps can be adjusted to compensate for the effect of different loads on headlamp vertical alignment. Headlamp levelling is controlled by a four position switch mounted in the centre of the fascia, which operates a levelling motor on each headlamp. Nominal vehicle loads for each switch position are as follows:

• 0 - Driver or driver and front passenger only; no luggage.
• 1 - All seats occupied; no luggage.
• 2 - All seats occupied; full luggage compartment.
• 3 - Driver only; full luggage compartment.

Headlamp levelling operates while the side lamps or headlamps are on.

OPERATION

Feed from the positive battery terminal is connected to fusible link 6 of the engine compartment fuse box (C1217-1) on a brown wire. Fusible link 6 supplies a feed to the lighting switch (C41-1) on a brown wire.

With the lighting switch in either the side or main beam position, current is allowed to flow from the switch (C41-2) to fuse 12 of the passenger compartment fuse box (C581-1) on a red wire. Fuse 12 (C581-4) supplies a feed to the LH headlamp levelling motor (C71-1), the RH headlamp levelling motor (C70-1), and the headlamp levelling switch (C93-4). All 3 are connected in parallel and are supplied a feed on red/orange wires. Fuse 12 also supplies a feed to the headlamp levelling switch illumination bulb (C93-5), again on a red/orange wire. All are earthed on black wires.

At each of the four switch positions, the contacts in the headlamp levelling switch connect to a different resistance value to provide one of four different output voltages. The output voltage (C93-2) is supplied to the LH (C71-3) and RH (C70-3) levelling motors on blue/yellow wires. The motors are earthed (C71-2 & C70-2 respectively) on black wires.

The difference between the voltage from the headlamp levelling switch and battery voltage is then used by electronics in the headlamp levelling motors to set the headlamps to a position corresponding to the switch position.