Greetings, all. Yep, I am a noobie with a 2010 FJ and this is my first post. I have searched high and low throughout this forum looking for detailed info on the factory auxillary lighting; in this case it is passing lights.
It is pretty cut and dried that these lights turn on with the high beams and that's it. What I intend to do is change the aux lighting so that the wire feeding the passing lights turns on only with the low beams. This will facilitate the installation of a set of fog lights cuz I can't see diddle on those dark rainy nights, and yes, the passing lights will continue to be used when the high beams are on. Switching between the two will be accomplished with a SPDT relay installed under the hood. On the off position (NC), current from the aux light wire will feed the fog lights. When the high beams are switched on, a wire tapped from the high beam wire will turn the relay on, breaking connection with the fog lights and switching the juice from the same aux lights wire to the passing lamps. This is pretty simple to accomplish. There is a problem, though, because I want to use the existing panel switch and wiring.... just because I like my installs very neat and tidy.
Why is there a potential problem? I have worked in electronics steadily over the course of the last 40 years, so I do know my way around electrical stuff. It is that knowledge, though, that raises a red flag in modifying the wiring. Long story short, on the schematics for a 2007 FJ provided by a number of fellow forum members, it would be simple to just move the current source from pin 3 of the factory AUX lighting switch from turning on with the high beams to another source that turns on with the headlights, high beams or low, such as the wire feeding the illuminated switch lights. But mine is a 2010 with possible electrical system changes- The crux of the situation is that with the aux light switch off, pin 3 turns on with the high beams and that's all. The part that I question is that when the aux light switch is on and the high beams are turned on, the +12Vdc on pin 3 goes away, too, down to ~1.5Vdc. This leads me to believe that when the high beams come on, the wire on pin 3 of the switch is being pulled low by the CPU, completing the ground to turn the relay on. Maybe another way to say that is that there is always 12Vdc on one side of the relay coil. But to turn it on, a ground is applied to the other side of the coil. Were I to put a 12Vdc wire to pin 3 of the switch then turn on the aux lights, it all becomes a "voltage-to-smoke converter" because I've sent that 12Vdc straight to near ground which would cause a fuse to blow at least, or at worst, frying the CPU.
Ya know, I could have just asked if anyone had detailed electrical schematics for the 2010 FJ? But I thought the "why" part was important, too.
I've already installed overhead VHF and cb radio equipment with decent luck. There's about 15lbs of stuff up there being held up by two roof ribs and the mirror. Bad picture, but good results!
Update: With time at a premium these days, I have backed up and will use the KISS method of installing the fog lights temporarily and keep their operation legal. It will involve just two relays in the engine compartment. The first relay's coil will connect to the marker/parking lights so that when the lights come on, it will turn on the relay that will pass juice from the battery to relay#2
, a SPDT relay. The coil for relay #2
is powered by the high beams. When Low beams are on, the fog lights get powered through relay #1
and through the N.C. contacts on Relay, @2. When the high beams turn on, Relay #2
is energized and feeds the battery voltage trhough the N.C. contacts to the passing lamps. Mission accomplished until spring where I will turn my attention back to the aux lights once again.