High beams don't work

[olinjohnston]

Hello forum,

So I have had this issue since I bought my W124.034 and I still have not yet solved it. The high beam headlights do not function, and I am not sure how to diagnose what is causing the issue.

The background facts:

- Pulling/pushing the stalk-switch illuminates the blue indicator in the instrument cluster, so I assume the switch works.
- No bulb failure warnings
- Replaced bulb monitoring control module with no results
- Checked headlight wiring for physical damage

 

[nocfn]

If all relays are good, then In my experience, the end of the stalk can be removed with a little flat jeweler screwdriver. Be very careful as the guts are spring loaded. Once out of the stalk, the metal contacts are very dirty and may need cleaning and some light roughing with an emery board. Isopropyl alcohol works well with a q-tip. Reassemble as reverse.

The switch could be worn out too but be warned, when that cap comes off the end, parts can shoot out under spring load... The springs are quite small(took me an hour to find one). If it works, it saves you from removing the wheel and airbag and so on.

 

[Klink]

Don't laugh, but have you checked both bulbs? Yes, it happens all the time.

FYI, there are no factory installed relays in your headlamp circuits.

Since your highbeam indicator works, the problem is likely occurring somewhere past the headlamp switch and the combination switch, which leaves the bulb monitoring unit itself, the bulbs, the wiring in between the ouput terminal of fuse number 16 (screw connection under the fuse box) and the wiring between the bulb failure monitoring unit and the lamps.

I am not in a position to supply you with a wiring diagram right now, but if it's not the bulbs, once you can get a wiring diagram you will sort this out pronto.

 

[luckymike]

May be related... My flash to pass was not working. I popped off the small cover at the column end of the turn signal lever and sprayed DeOxit5 contact cleaner in there. Then worked the switch a bunch of times. That did the trick.

Might help you, too.

 

[Klink]

Good time to introduce some jargon. The "flash to pass" high beam function is sometimes referred to as the "optical horn"

 

[gsxr]

If your .034 is 1992 or 1993, check the connectors at the bulbs... they melt with higher-wattage bulbs:

 

[nocfn]

Gsxr is a show off

 

[olinjohnston]

Don't laugh, but have you checked both bulbs? Yes, it happens all the time.

FYI, there are no factory installed relays in your headlamp circuits.

Since your highbeam indicator works, the problem is likely occurring somewhere past the headlamp switch and the combination switch, which leaves the bulb monitoring unit itself, the bulbs, the wiring in between the ouput terminal of fuse number 16 (screw connection under the fuse box) and the wiring between the bulb failure monitoring unit and the lamps.

I am not in a position to supply you with a wiring diagram right now, but if it's not the bulbs, once you can get a wiring diagram you will sort this out pronto.

Thanks!

If the bulbs were both bad, wouldn't that cause the bulb failure warning to come on?

If your .034 is 1992 or 1993, check the connectors at the bulbs... they melt with higher-wattage bulbs:

Yes it is a mid-1993. I will definitely check that out.

 

[Klink]

Thanks!

If the bulbs were both bad, wouldn't that cause the bulb failure warning to come on?

One would think, but some of the bulb failure monitoring systems work by comparing the current flow between the left and right. This may be one of them. It's a longshot, but it is one that has been overlooked and wasted a great deal of time and money for people over the years. Other than fuses, it's by far the cheapest and easiest thing to check first.

 

[olinjohnston]

Dual filament bulbs - both highs blown.

Thanks!

 

[superstar]

Had a similar problem, I replaced the combination switch/stalk with original part (not cheap), problem gone. Cleaning the contact of the old switch is a temporary fix and eventually will fail again.

 

[Axvel]

How do you clean the contacts?