No low beam headlights

[mike52787]

This morning I got into my e500, switched the lights on and found I had no low beams. All of the other lighting worked fine, but alas no low beam headlights. I just checked the fuses for the low beams and they are fine, however there is no power at those particular fuses with the headlight switch on. Am I chasing a bad headlight switch or some other problem? At one point in the past the dash lights did not come on the first time I turned the headlights on, but worked fine after cycling the switch. that makes me think the switch is the most likely culprit. any ideas?

 

[gsxr]

Headlight switch and combo switch are the primary suspects. My guess is the combo switch, because if it were the rotary switch I don't think you'd have high beams either.

 

[mike52787]

Tried another known good headlight switch off a parts car (wrong switch for 036 with foglights, but still plugs in) and still no low beams. now i'm puzzled.

 

[gsxr]

Tried another known good headlight switch off a parts car (wrong switch for 036 with foglights, but still plugs in) and still no low beams. now i'm puzzled.

Combo switch or, less likely, a defective bulb-out module/relay. I've had to replace more than one combo switch... get 'em while you still can.

 

[mike52787]

the little black single wire pigtail coming off the combo switch connector is not connected to anything, is this normal? where does it go?

 

[gsxr]

the little black single wire pigtail coming off the combo switch connector is not connected to anything, is this normal? where does it go?

Yep, I believe that is normal. MB consolidated a couple different switch p/n's into a single and not all chassis use the pigtail. Now I'm curious if your combo switch is original, or aftermarket...

 

[mike52787]

Confirmed! it is the combo switch. Pulled the one off the parts car, plugged it in, and have lights again. Thank you gsxr! I will order a new one and a spare.

 

[tomer]

Glad you found the culprit!! Is removing the steering wheel and airbag a must for replacing the combo switch? My high beams don't work while everything else works, I suspect the combo switch (turn signal lever). I am a little afraid of the air bag!!!

 

[mike52787]

Glad you found the culprit!! Is removing the steering wheel and airbag a must for replacing the combo switch? My high beams don't work while everything else works, I suspect the combo switch (turn signal lever). I am a little afraid of the air bag!!!

Yes, but it is pretty straightforward and can be done by anyone. just make sure you disconnect your battery before unplugging the airbag of course. all you need is a torx t27, 10mm male hex socket on a breaker bar, and a philips screwdriver. it probably takes about 30 minutes to an hour to do

 

[Jlaa]

Yes, but it is pretty straightforward and can be done by anyone. just make sure you disconnect your battery before unplugging the airbag of course. all you need is a torx t27, 10mm male hex socket on a breaker bar, and a philips screwdriver. it probably takes about 30 minutes to an hour to do

You can also use an impact driver with an 18V battery from Ryobi/Milwaukee/Dewalt/whatever if you like.
Takes 2 seconds to zap off the nut and you don't have to worry about using the breaker-bar as a breaker-of-windshield.

 

[tomer]

Excellent advice!!! I recently purchased a 3/8 drive Dewalt 20V impact driver and have not had a change to use it!!!

 

[gsxr]

+eleventybillion on what @Jlaa said. Impact wench is the way to go for removing the nut behind the steering wheel. I mean in the middle of the steering wheel.

However, I don't know if a 3/8" impact will have enough oomph to do the job. Most 1/2" can do it no problem. Use the shortest extension possible, even my 1/2" won't work if the extension is too long, it absorbs the impacts and doesn't transfer torque to the bolt head.

 

[nocfn]

Take care to not over tighten the knee bolster. If you are too tight on the top and right side gaps you will squeak like a stuck pig!