Schematics/Diagrams

Wiring diagram of our reverse polarity circuit

12v supply fused, 2 relays, a door lock, and a SPST switch

 
Last week was another interesting week in relays and electrical fun.  Jared and I wanted to find a way to reverse polarity using a SPST switch and two relays.  The diagram we came up with looked to be the most simple way of accomplishing this goal... and it worked!  As a sidenote, because we were using a door lock mechanism we had to very quick as we flipped the switch back and forth.  There were a few burned up fuses before we finished :)
  The light boards continued to give me quite a headache throughout the week.  I realized that the way that I had the light boards set up worked, but were not wired in exactly as the schematic shows.  The headlights, in particular, were shown on the schematic as being a ground control circuit.  In the picture below, the headlights have switched power coming from the headlamp switch that supplies power to the contacts of the relay (both high and low beam relay, or 87 and 87a on the relay).  When the high beam push button switch is pushed, the relay coil energizes and moves the contacts over.  What is different than what I thought is that the ground (blue wire in diagram) is connected from the ground side of the relay coil to the previously thought 'always power', or 30 on the relay.  This means that the headlights are not grounded directly, but have the 'control' on the ground side of the load.
  I was really happy to be able to learn a different way of wiring something as simple as a headlight and switch.  If I am working on a truck and think I know the way it is wired, I could potentially wire it wrong.  This would cause more headaches than I ever need in electrical troubleshooting.  This could be the most invaluable thing I've learned so far:  learn to read your diagrams/schematics.  I may know how to wire that particular board by heart, but as I go on in my career I am destined to see a lot I don't actually know how it works.  Reading plans is priceless.

Wiring diagram of High/Low Beam circuit

Week 2 hrs: 32

Total:  56