BMW Motorcycle Turn Signal Relay
Replacing a turn signal or directional
relay on a BMW R100RS
I recently purchased an R100RS (see
photo), and as I was going through it to check
the routine maintenance and prepare it for the state's motor vehicle
inspection, I noticed that the turn signals were not working
When the turn signal was on in either direction, all 4
directional lights would come on and stay on without blinking. This
led me to believe that the turn signal relay was not working
I first thought that I would have to remove
the entire R100RS fairing to get to the relay, which is buried inside the
headlight shell. However, Bob Fleischer of the BMW Airheads list
sent me a great tip on accessing the headlight shell without removing the
Maybe the experienced R100RS owners know about this trick,
but I figured I'd post some photos anyway for those who don't.
Thanks to Bob "Snowbum" Fleischer
and the Airheads.org website for this Airhead inspiration!
Here's my tip: Since the
headlight will have to be moved during this job, it's a good idea to have
a reference point for where the headlight is aimed so that you can realign
the headlight when you're done.
So before you start this project,
turn on the headlight and make a mark on the garage wall to indicate where
the beam is aimed. If your bike is on its centerstand, make sure the
front wheel is on the ground before you do this. Checking the
headlight alignment first will help you to get the headlight realigned
after you're replaced the relay.
By the way, you can adjust the
headlight without having to remove the glass on the front of the
fairing. To move the headlight shell for alignment, first sit on the
bike and reach around the handlebars into the fairing. You should be
able to grab the headlight shell and move it slightly up or down to aim
Peel back the rubber
gasket that surrounds the glass that protects the R100RS
headlight. On each corner, you'll see a small Phillips head
Carefully remove the screws -- be
careful not to damage the glass. I used a thin magnetic
Phillips head screwdriver, which held the screws as I removed
There's not much room for your
fingers when removing the screws, but they should come out with no problems.
I had to use a pair of needle-nose pliers to grab the head of one
screw to remove it after it was loose.
The headlight is now accessible. The
headlight shell is held by two rubber bushings on either
side, which are tight but allow movement for aiming the
Carefully push the headlight assembly up to access the Phillips head screw at the bottom of the shell (yellow arrow, photo left).
Unscrew the Phillips head screw at the bottom of the chrome headlight surround. It's not necessary to completely remove this screw.
Carefully pull the headlight out from the bottom. The top is hooked over the top of the headlight shell, so lift it up and over and you should be able to easily remove the headlight. Carefully pull off the 3-prong H4 light bulb plug.
You now have access to
the internals of the headlight shell. The turn signal relay
is the green box on the left. There are some fuses on the
back circuit board that you may want to check and
I first tried re-inserting the old
relay, but the turn signals still didn't work correctly. I
replaced this relay with a new one, and the turn signals worked
Does your headlight have that
"foggy" look? While you have the headlight off,
you can clean up the foggy insides by pouring in a little rubbing
alcohol and swishing it around. It cleans up very nicely and
shines like new and takes away any fogging. I turned it
upside down to let it drain, then gently blew it out with
compressed air until it was dry.
I also cleaned the H4 bulb with
alcohol. Don't touch the bulb with your fingers when
re-installing. I went all out and removed the glass from the
gasket and got the glass nice and clean inside and out, then
cleaned up the rubber gasket also. I then cleaned up the old
dried up wax that collected under the edges of the gasket on the
bike. Everything looks like new!
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