W164 front light bulb replacement - PeachParts Mercedes-Benz Forum

jay_bob · #1 01-02-2016, 06:52 PM

Well it happened today. Got smacked by a piece of road debris, not hard enough to do any damage except to blow the marker and parking light filaments in the front left corner. It was a piece of rubber from a mud flap I think.

So I got home and went to check the owners manual. It helpfully told me I needed to twist the socket and pull to remove the bulb. Duh. The problem is that no human can contort their hands back to where the sockets for these two bulbs are.

Went online and everyone said you have to pull the front bumper cover and grill, then remove the headlight assemblies. It seemed pretty intimidating but my son and I figured it out in about an hour.

Go buy the following bulbs, these are the impossible to reach bulbs without pulling everything apart and you will want to change them all.

2x 2825 (parking)
2x 2827 (marker)
2 x H11 (fog lights)

The low and high beam headlights, and the turn signals, can be (relatively) easily changed without disassembling anything. But if you want to go ahead while you're at it, you'll need

4 x H7 (high and low beam)
2 x 3457A (turn signal)

First put the vehicle up on ramps, much easier to work on the front when it's up in the air, and probably much easier to insert and remove the wheel well linings when it's up. You could also save some time by putting the car up on stands and pulling the front tires but that's probably 6 or 1/2 dozen.

Everything is symmetrical for removing the bumper cover so I will only describe one side.

First remove the front half of the underbelly pan. 10 mm bolts, there are 7 in total. Drop pan and slide back under car.

Next go into the wheel well, remove 3 push pin fasteners on the outer edge. You want to remove the forward half of the liner. After removing the 3 push pins find two 10 mm plastic nuts, one at the top in a depression, and the other behind the tire about in line with the axle. Then remove two 10 mm bolts at the top and two more at the front edge under the bumper. Carefully work the liner out of the wheel well.

Now from under the hood remove two push pins on the center line, holding the grill to the radiator support. Now at the edges of the grill find 2 more 10 mm bolts. Leave the grill attached at the bottom to the bumper cover.

From inside the wheel well there is a bracket clamping the edge of the bumper cover to the edge of the fender. Like this: =]. Remove the T20 Torx screw that is just inside the wheel well pointing up. Then using a nail or pointed tool lever the edge of the bracket inboard to release it from the joint between the fender and bumper cover. There is a pivot pin at the back end of the bracket that hooks into a slot in the two metal pieces to align and secure them together.

Now go under the car and remove the four 10 mm bolts holding the bumper cover to the frame of the car.

Before going further look at the top of the headlight housing. You will see a tab that extends back to the radiator support. Mark around the perimeter of this tab so that you can get the headlight back in the same place. The headlight is supported in 3 places but this one has the most slop. The other two are pretty much fixed points.

Now remove the 10 mm bolts at the inboard ends of the light assembly, these also support the bumper cover as well as the headlights.

Arrange a device to support the bumper cover after it is removed. A couple of overturned recycle bins with towels on them works great.

At this point the bumper cover should be free. Gently pull straight forward, there are two C shaped notches that fit over a rubber knob inside the wheel well. The bumper cover notches just pull straight out of these knobs without having to unbolt anything. Work the upper supports (inboard of the headlights) free and gently pull the bumper off the car. Lay the bumper cover down on the support. Be careful, the grill is only supported by the bottom clips, so support it while removing the bumper cover.

There is a wiring harness that needs to be unplugged for the fog lights and outside air temperature sensor. Unplug this harness and now the bumper cover may be moved aside. Change the fog light bulbs (unplug the connector, rotate out old bub, insert new bulb and lock in, plug in connector). Yes, you can change the fog lights from the front, but why risk breaking the lens assemblies trying to pry them out...much easier to access in the rear while you are here.

Now the headlight assemblies may be removed. On the side in the wheel well there is yet another 10 mm bolt. Now remove the 10 mm bolt from the bracket at the radiator support. Gently pull the light assembly forward. Flip it over, disconnect the connector and remove the parking and marker light sockets (these are quarter turn and draw out). Set the headlight assemblies aside. Change the high and low beams and turn signals if you wish while you are here.

Change the marker and parking light bulbs. The gray socket is the marker (amber) bulb and the black socket is the parking (clear) bulb.

At this point before I started putting everything back together, I decided to turn on the lights to see if these new bulbs worked. Well this car is too smart for its own good, and won't let you turn on the lights unless the key is in the II position. When you do this, it also wakes up the other systems, and a CEL is set because the outside air temperature sensor is unplugged. If you have a generic OBDII reader, it will show U0423 (instrument cluster data fault), and fortunately you can erase the fault to clear the CEL. If you do not have access to a reader, I would not turn the car back on until everything is plugged back in.

Ok just like Haynes says, reverse steps to reassemble, just watch the following:

- Use your witness marks when setting the headlight back in place.

- Be careful setting the bumper cover back in place, watch the edges of the fender. Don't forget to plug the harness back in.

- Be sure the C shaped notches in the bumper cover enter the groove in the rubber knobs properly.