Dead High Beams - Page 3 - PeachParts Mercedes-Benz Forum

scottmcphee · #31 10-28-2010, 11:08 AM

The burned out bulb indicator on the dash for headlights goes on only when power is applied to the particular bulb circuit of interest. It will come on if one or both bulbs are out-of-spec, burned out, missing or incomplete circuit (open). N7 measures side/side imbalance in stereo pairs, and current over/under from an expected standard (dictated by having the correct bulb type).

This may be a clue. Here's a diagnostic: pull one head light bulb out, so for sure it won't work. Then start your car and turn on the headlight switch. If your bulb out indicator does not come on when you go to high beams... then power is not making as far as N7 (the black box that measures current imbalance for external lights). Or, N7 is having an issue (not seated fully?). Power must pass through N7 for each circuit it measures. If N7 is missing, you also get no lights.

Experience has taught me all this... check out this related thread on how I mod'ed my headlights for more light.
W124 Headlamp Voltage

babymog · #32 10-28-2010, 12:41 PM

Do they come on when you pull the stalk toward you (flass to pass)?

freesoul · #33 10-28-2010, 02:49 PM

Quote:

Originally Posted by babymog

Do they come on when you pull the stalk toward you (flass to pass)?

No they have never come on since I have had the car, 2 years. Wife has the car so will have to wait to later to check out the headlight connections

freesoul · #34 10-28-2010, 05:56 PM

Quote:

Originally Posted by scottmcphee

The burned out bulb indicator on the dash for headlights goes on only when power is applied to the particular bulb circuit of interest. It will come on if one or both bulbs are out-of-spec, burned out, missing or incomplete circuit (open). N7 measures side/side imbalance in stereo pairs, and current over/under from an expected standard (dictated by having the correct bulb type).

This may be a clue. Here's a diagnostic: pull one head light bulb out, so for sure it won't work. Then start your car and turn on the headlight switch. If your bulb out indicator does not come on when you go to high beams... then power is not making as far as N7 (the black box that measures current imbalance for external lights). Or, N7 is having an issue (not seated fully?). Power must pass through N7 for each circuit it measures. If N7 is missing, you also get no lights.

Experience has taught me all this... check out this related thread on how I mod'ed my headlights for more light.
W124 Headlamp Voltage

OK so the historical with the bulb indicator is sometimes it is on, sometimes off. When I just went out to check on the connectors to the headlights everything looks fine. I pulled the left side connector and started the car and put the headlights on. The bulb indicator light only comes on when I pull the stalk back to flash then stays on until I turn the lights off.

The fogs work fine, aren't they supposed to go off when the stalk is pushed forward for high beams? They do not even flicker.

One thing I noticed is the right side headlight assembly was obviously hit by something and the plastic part that attaches to the front of the car is broken. Also the reflector inside the housing moves around. I will be obtaining a new one asap.

I am still stumped by leaning towards the combination switch being bad based on my continuity testing. Any other thoughts? I need to get this car inspected by the end of the month and need working high beams for that. thanks!

bobodaclown · #35 10-28-2010, 07:12 PM

I replaced my combo switch. It was bad. (No high beams). Got one that was pulled. You have to pull the steering wheel. Not like a 123.

freesoul · #36 10-28-2010, 08:14 PM

Quote:

Originally Posted by bobodaclown

I replaced my combo switch. It was bad. (No high beams). Got one that was pulled. You have to pull the steering wheel. Not like a 123.

I thought I read somewhere that you could do it without pulling the wheel

babymog · #37 10-28-2010, 08:48 PM

You can not install it without removing the wheel, fortunately removing the wheel is a simple job. The hardest part is getting the allen-head bolt to break free, I always use an allen bit in a ratchet, with a box-end wrench over the allen bit so that you can use the ratchet in one hand, the box-end wrench in the other hand, like a Tee-handle. Not keeping the bit straight in the bolt-head can damage it enough that removal will become impossible.

Don't be afraid to apply lots of force, I believe that the steering lock in the 124 is a beefy one that was designed to deter theft well, I've removed at least a dozen wheels this way and it works well.

Anyway, the switch is plugged in under the dash, you'll need to remove the lower dash panel (above the cruise-control amp). Then you can test the new switch by plugging it in, before going through the whole wheel-pulling exercise to install it.

Please however, check the fuses first. Not just visually, but with a test light to ensure that there is actually power on the top of the fuseholder. Corrosion and bad connections plague this fuse system.

The fog-lamps are supposed to stay on with the high beams.

freesoul · #38 10-29-2010, 01:24 PM

Quote:

Originally Posted by babymog

You can not install it without removing the wheel, fortunately removing the wheel is a simple job. The hardest part is getting the allen-head bolt to break free, I always use an allen bit in a ratchet, with a box-end wrench over the allen bit so that you can use the ratchet in one hand, the box-end wrench in the other hand, like a Tee-handle. Not keeping the bit straight in the bolt-head can damage it enough that removal will become impossible.

Don't be afraid to apply lots of force, I believe that the steering lock in the 124 is a beefy one that was designed to deter theft well, I've removed at least a dozen wheels this way and it works well.

Anyway, the switch is plugged in under the dash, you'll need to remove the lower dash panel (above the cruise-control amp). Then you can test the new switch by plugging it in, before going through the whole wheel-pulling exercise to install it.

Please however, check the fuses first. Not just visually, but with a test light to ensure that there is actually power on the top of the fuseholder. Corrosion and bad connections plague this fuse system.

The fog-lamps are supposed to stay on with the high beams.

Checked the fuses earlier, with switch pushed to high beams there was no power to top of fuses. Well let me correct that there was like .3V

I am thinking I am better off buying the combination switch new rather then used, can get it for $140 locally.

freesoul · #39 11-02-2010, 10:53 AM

Replaced the combination switch last night and finally after 2 years have high beams!

Fairly easy procedure, make sure to disconnect the battery first and then the red airbag connector under the passenger footwell (pull up carpet/insulation piece then one bolt and remove the metal plate)

You need a slender T27 torx screwdriver to get the airbag bolts. The 10mm nut needed a little torque and I just used a breaker bar and short piece of pipe and had a friend hold the wheel. Once you have the wheel off there are 2 small screws to remove the black plastic piece (shown hanging in below photo) and then 3 screws to remove the cruise control stalk and pull the combo switch right out.

Before I tore mine apart I disconnected the old one underneath and plugged the new one in to confirm that it was bad.

babymog · #40 11-02-2010, 12:23 PM

One important step IMO is to extend the steering column before disconnecting the battery.

Oldwolf · #41 11-02-2010, 02:11 PM

My W124 must be the rare one w/o the telescoping steering column.

babymog · #42 11-02-2010, 02:13 PM

Little switch on the left side of the column, pull or push it to make the column move.

Oldwolf · #43 11-02-2010, 02:19 PM

Nope. Mine doesn't have a switch. Not a great picture but there is no switch.

FrodeS · #44 11-02-2010, 05:57 PM

There is no relay on this cars, just the lamp control to check wether any bulbs are not working.

The fuse hazzle is probably well meant. The fuses may look good, but still no contact. Try rotate them a couple of times before doing anything else. I don't think this will help, because there is one fuse for each lamp, and they probably both don't stop working at the same time.

If rotating the fuses don't help, try move the light switch a little back and forth. Probably, you have a malefunctioning light switch (not the one on the steering column)

bobodaclown · #45 11-02-2010, 06:50 PM

The switches are almost 20 years old. They wear/break. Glad you got it working. My steering wheel doesn't adjust either.