4dr.no

iTrader: (1)

Did a dozen searches in multiple forums and cannot find an answer as to what might be causing my high beam to be out while the low beam works fine. Driver side on my 2001 CLK55.

Did A/B switch, it's not the bulb.
Replaced ballast, still no high beam (btw if a ballast goes, won't both lights go out?)
Switched entire headlight assembly from driver side to passenger side, same result so wires must be OK.

Any other ideas?

burgca

The OEM setup high beam is the "driving" light H7 55W and shouldn't need a ballast (only Xeon needs ballast), you must have short somewhere. Is this stock or aftermarket setup?

4dr.no

iTrader: (1)

Stock xenon set-up. Bulb is not the problem.

Serndipity

I'm perplexed by the troubleshooting steps undertaken in post #1, as the low / high beam circuits in Xenon equipped W208s are independent.

For stock Xenon lighting, only the low beams are Xenon (e.g. bulbs with ballast). The xenon bulbs, along with the turn signal bulbs are located behind the larger lens, of each headlamp assembly.

The high beams use a traditional type H7 (55 watt) bulb, which is located behind the smaller lens, along with the parking/standing bulbs, of each headlamp assembly.

See the 'practical hints' section of your owner's manual for more information.

The high beams are turned on/off via the combination switch stalk, located on the steering column. If the low beams are on, the high beams can be added, by pushing the stalk forward. Additionally, pulling the stalk rearward, the high beams can be flashed, without the low beams being activated.

Troubleshooting the high beam electrical system can usually be done just using a multi-meter, starting at the input (the combination stalk switch), verifying that it and then moving to the output (the high beam lamp) that each succeeding component in the chain (the wiring, fuses, relays, lighting control module, connectors etc.), check out (e.g. produce the expected voltage or resistance).

Lastly, if I read your OP correctly (e.g. only the drivers side high beam is not operating), 2 suggestions.

Check the fuses in the lighting fuse box, which is located on the side of the dash (drivers side). As I recall, the left and right side high beams are separately fused..

Check the high beam bulb and it's connector, at the location mentioned above, as well as adjacent wiring for possible insulation failure (short circuits).

4dr.no

iTrader: (1)

I used the wrong terminology.
The larger driving headlamp is not working in low beam.

Serndipity

When the left Xenon low beam headlamp (E1) does not function, possible causes are:

Fuse (N7-1 F8)
Xenon headlamp (D2R, 35W)
Illumination control module (N7-1), wiring
Xenon headlamp control module (E1n1) with Xenon headlamp ignition module (E1n2)