Here's a neat little idea I came up with and thought I would share with all you E30 owners out there. This simple modification will allow you sidemarkers to blink along with the turn signals. This article is specific to my E30 325is, however this simple modification will apply to nearly every E30 model from 1984-91.
A note to all those attempting this, Be sure to take a look at an electrical schematic for your car before proceeding. The colors of the wires on my car might be different than those on yours. If anyone wants to do this, but does not have access to a wiring schematic, email me at and I can look this info up for you. Here at pelican, we have a large reference of BMW electrical schematics for nearly every model.
Disconnect the battery first. Do this anytime you are working around electricity. You don't want to send a random spike through the electrical system.
That said let's begin. First, remove the side marker assemblies in the front by inserting a small flathead screwdriver into the side and pry them out. Now on each sidemarker, pull back the black protective insulation and find the brown wire going to each. This is the ground wire. Now cut the wire about 2 inches back from the sidemarker. Now use some electrical tape to cover the wire coming out of the harness. We will not be using this wire anymore, so it's important to make sure it does not contact the chassis, possibly causing a short in the system.
Now take a wire stripper and strip off about 1/2 inch of insulation from the brown wire on the sidemarker. Now get some wire and cut off an 8-inch piece and strip off 1/2 inch of insulation from either end. Using a crimping tool and a female-to-female connector, connect one end of the 8-inch piece of wire to the brown wire.
Now, locate the front turn signal wiring harness connector. This is the piece that plugs into the turn signal. In early models with chrome bumpers, you should be able to just reach in through the sidemarker holes and pull it off and through the hole. In the later cars with plastic bumpers (like mine) you will have to remove the front bumper in order to access the connector. This is easy. Just remove the two mounting bolts for the bumper in the front and pull it forward. Once free, disconnect the harness.
On the turn signal harness, you will see three wires. Look for the blue wire. This is the pulsed voltage coming from the turn signal relay. This is the voltage we will tap into in order to make the sidemarkers work. Connect the 8-inch piece of wire to the blue wire using a quick splice or other type of connector. These types of connectors allow you to tap into power leads without having to cut insulation.
Once connected, tuck all the wiring inside the bumper and plug the turn signal harness back into the turn signal (put the bumper back on now if you have to) and pop the sidemarkers back into the body. And that's how to take care of the front markers.
Now for the rear sidemarkers, pop the sidemarkers out in the same manner as described before with a flathead screwdriver. Pull back the insulation and cut the brown wire about two inches back from the sidemarker. Now insulate the wire out of the harness. Strip about 1/2 inch off the brown wire off the sidemarker. Cut a section of wire about 10 inches and using a crimper and a female-to-female splicer, connect it to the brown wire out of the sidemarker. Route the wire through the body and up through the trunk under the trunk liners until it is near the wiring harness for the taillights.
Next, open the trunk, and remove the rear light bulb holders by rotating the black plastic knobs and pulling both holders out. Pinch either side of the wiring harness and pull it out. Now pull back the insulation and locate the blue wire coming off the harness. Now using a quick-splicer, connect the 10-inch piece of wire to the blue wire. Now pop the wiring harness back into the taillights and re-install the bulb holders. Route the 10-inch piece of wire under the trunk liners to keep it out of sight and make it look nice in the trunk.
Well, there you have it - it's really not too difficult at all. If you would like to see more technical articles like this one, please continue to support Pelican Parts with all your parts needs. If you like what you see here, then please visit our online BMW catalog and help support the collection and creating of new and informative technical articles like this one. Your continued support directly affects the expansion and existence of this site and technical articles like this one. As always, if you have any questions or comments about this helpful article, please drop us a line.