HOWTO: Wire up those S13 Silvia Fog Lights "56k BEWARE!"

[radhaz]

Safety Notice: Work on your car at your own risk. While this project may work flawlessly in my car it might cause your's to explode. Having said that evaluate what you are doing carefully electrical fires are no fun

Hello all I just wanted to shed some light on wiring up the silvia fog lights in the triple projectors. Many folks already know how to wire the lights into the existing circuitry by splicing into the brown and the black wire located on the old popup harness. That is initially what worked for me and I had no complaints as the pop-up button functioned as a foglight on/off button & whenever I turned on my headlights at the stalk the foglights would also come on.

It wasn't until I was following a friend that it was pointed out to me that when the headlights were on the foglights were prone to random flickering. I could resolve this problem by turning the pop-up button on but to me that wasn't an acceptable permanent solution. I decided to take the time and go over the 90 240sx schematics and figure out how to isolate the stalk from turning on the fog lights and just allowing the pop-up light to work. Initially I was overwhelmed by the mess of diagram's nissan passes off as schematics, but once I got to tracing it out on paper I was able to come up with a ridiculously easy fix. All you have to do is remove the retractor relay #4 and this knocks the headlight timing circuit out of the loop for the fog lights. In the attached schematics I took the time to highlight the path the current takes through the circuit "Blue" is for the circuit under battery power, "Green" is under alternator power, Red is for the power that gets sent from the pop-up switch to the lights (This power you can see comes from either the alternator or the battery source). I took the time to include the diagram of the engine bay and highlighted the relay to pull.

Further inspection of the relay ladder resulted in me removing all 4 retractor relay assemblies; however, if you chose to remove relay's 1 & 2 you will have to jumper the connections that are NOT across the coil. This has to be done because the relay is an NC type (Normally Closed) and when you pull the relay you open the circuit and remove the ground signal going to your headlights.

I hope this is useful for anyone out there trying to figure out how to wire up the circuit or how the circuit works. If anyone care's to point out mistakes or misconceptions I would be happy to discuss them. I am a technician and not an engineer so I'm bound to have oversimplified it Feel free to ask questions and I will be happy to address them.
Here is the Diagram in question