Now that we have determined if the voltage getting to the bulbs is a problem or not, it is time to complete the repair.
Here are a few ways to repair it.
You can either run all new wires, in the same way that OEM wires are ran.
Or the way that I did it, you can install relays into the system.
A relay is a big switch. It uses 2 circuits. one side of the relay is the control side, the other is the load side. Here is more information: Relays Explained
To wire in the relays, start by getting all your supplies.
A few things I used::
1. 2 ISO standard 5 prong relays.
2. Relay Holders
3. about 10 feet of 14 or 16 gauge wiring.
4. Shrink Wrap
5. Solder and a Soldering Iron
6. Zip Ties
8. DVOM or Voltmeter
Now, since your OEM switch will be used to control the “control side” of the relays, we will keep all the wiring before the switch and some after the switch in tact. Even if the wires you know have about 10 or so volts, it is still plenty of current to control the relay.
We will be using 2 ISO relays, one for low beams and one for high beams.
And 2 Relay holders.(Much easier to use the relays, it involves no soldering straight to the relay itself, just to the lead of wires coming off the holder.
I started off by cutting the power wire to each bulb. You can do them one at a time so you are not stuck without headlights if you run out of time.
The wires that are in the bulb connectors, are going to be wired to each other, right low beam to left low beam and right high beam to left high beam. i ran the wire under the fender, like the hood release cable.
Now, the 2 sets of bulbs that you have wired together need to be ran to pin 87 of each relay. I did my low beams all at once, and then my high beams so I wouldn’t get things too mixed up!
The grounds for each headlight can stay if you did not see a high amount of voltage lost on your ground side.
I did nothing with the grounds of the bulbs. If your problem area is the ground side, cut the ground wire and run a new ground wire.
You also need to find a good ground for the relay. Run the wire from pin 85 of each relay to a good ground.
Next, the red wire that goes back into the wire harness, goes to the switch inside the car. You only need to use one of these to do the next part because they both do the same thing. So you can just tape one of them off. The other goes down to pin 86 on each relay.
Now run a wire from the battery + post to pin 30 of each relay. Be sure to run an inline fuse holder in series near the battery post. I used a 30 Amp fuse, because the OEM headlight fuses were 40 Amps.
The pin numbers of the relays should be engraved on or have a picture on the relay somewhere. If not, refer to the relay’s explained article.
After all is complete, your headlights should turn on the same as they always did, except this time, quite a bit brighter.
Now get out your DVOM and t-pins again and do the same voltage drop test as we started out doing. You should get a number quite a bit higher than you started out with.
Hope this helps! Good luck with fixing all those dim lights.
Here are some before and after shots of my project!!
Quite a difference i would say!!!