Hard-wiring Tail-lights

OK, I thought this idea up because my tail lights have a lot of problems. After getting pulled over many times for having a bulb out that just turned out to be a bad connection, I got sick of it. So I pulled out my handy soldering iron and ran wires to all the bulbs in the tail lights to replace that printed-circuit piece of plastic crap that was causing the bad connection.

The car is a 1981 Volvo 242 GLT-Turbo. Not all Volvo’s have this printed circuit. Many have real metal that works fine. 240 wagons and 240′s with the 5-panel tail-lights do not need this upgrade.

Here’s what you’ll need:
8mm deep socket and ratchet
Phillips screwdriver
Soldering Iron and lots of solder
Wire (18 guage is best, I used 16. Getting OEM colors would be a nice touch)
Shielded connectors (bullet or spade)
Ring-terminal connectors for ground wires
Wire cutters/strippers
Permanent marker
Shop knife
Sand Paper

Ok, first, take all the junk out of the trunk, including the spare tire. Now, unscrew the plastic knob that holds on the plastic cover that is on the inside of the tail light.

Once that is off, unplug the tail light wiring harness from the tail light. (white plastic connector). Unscrew the tail light grounding screw. Remove the tail light by taking off the four 8mm nuts. Carefully pop the tail light off of the car, pushing from the inside of the trunk. Be careful not to damage the rubber seal or the light itself of course. Here’s what it should look like:

Now, you’ll need to remove that rubber seal and set it aside. Look at the blue printed circuit and figure it out. It’s pretty straight forward. All of the light bulbs share a common ground wire that runs around the edge of the circuit board. The “+” wires are the yellow, brown, blue, and black wires that connect to the white plug. I don’t know what the white wire does; on my car, it doesn’t go to anything. Oh well.

Get out your permanent marker and mark up the blue printed circuit with the color of wire that goes to what bulb so you’ll be able to hook things up right later. Also mark each bulb holder so you know what one’s go in what holes. They are mostly interchangable, but it makes it easier to keep them straight later.

Next, remove each bulb holder from the tail light and remove the bulbs from the holders. Set the bulbs somewhere safe. Find the plastic tabs on the holders that cover up the metal tabs that go to the light bulbs. Cut off these plastic tabs with the shop knife. An alternative method is to melt them off with the soldering iron. These tabs don’t seem to do much and will really get in your way when soldering if left on.

Get your sand paper and sand all the tabs so that the solder will stick to them. Using the blue printed circuit as a guide, cut wires of the appropriate lengths and strip the ends with wire strippers. Now solder the wires to the metal tabs, duplicating the layout of the blue printed circuit. Solder to the “back” side of the tabs so that you can still screw in the bulb holder when you’re done.

Here is a picture of the light about half way done. All of the “+” wires have been soldered. Next I did the ground wires. I only had red 16 guage wire, and I didn’t want to pay for more wires. However, it would have been easier with 18 guage color-coded wire of course.

Now, wire the ground wire. You can do one ground wire, but I did two. One for the lower two bulbs and one for the upper three bulbs. Now put ring terminals on the ground wires and bullet/spade connectors on the “+” wires. Here’s a pic of the completed light

You can use zip ties or whatever to keep the wires together. Next, just cut off the old white plug that is attached to the car and put bullet/spade connectors on those. You could just solder them instead of using connectors, but I wanted to still be able to remove the tail lights later if necessary.

Now put everything back together and do the other side. As far as the “Bulb Failure Warning Light” on the dashboard, this may make it start flashing. However, my bulb failure light went on any time a light was on in my car, even when they were all working, so I just removed the bulb from the back of the instrument panel to keep it from driving me crazy. If you do everything right, this shouldn’t bother the warning light system at all, but you never know.

It works! (brake and reverse lights not shown)