billyjones454 Posted April 23, 2023 Share Posted April 23, 2023 (edited) I am re-doing all the wiring in the car with a modern fuse and relay box. Pictured below are 2 options for switch locations. Either on the positive or negative side of the relay. With my admittedly limited knowledge, there seem to be some advantages to putting the switch on the negative side. 1. No need to fuse the wiring to and from the switch (obviously all pos. wires still need appropriate fuses) 2. Almost half the switch wiring is eliminated since the ground can be placed near the switch. Are there disadvantages that I'm missing? Unless there is some obvious disadvantage, I plan to put switches on the negative side for the reasons stated above. However I realize there is still a lot I have to learn. Thank you for your comments! Edited April 23, 2023 by billyjones454 Quote Link to comment Share on other sites More sharing options...
NewZed Posted April 23, 2023 Share Posted April 23, 2023 Are you putting in new light switches? Getting rid of the combination switch? Not clear what you mean by light switch. One consideration is what happens if there's a short in the wiring before the switch. With supply control the fuse blows. With ground control the device turns on. Quote Link to comment Share on other sites More sharing options...
billyjones454 Posted April 23, 2023 Author Share Posted April 23, 2023 48 minutes ago, NewZed said: Are you putting in new light switches? Getting rid of the combination switch? Not clear what you mean by light switch. One consideration is what happens if there's a short in the wiring before the switch. With supply control the fuse blows. With ground control the device turns on. Sorry, I'm keeping all the original switches, which is one of the reasons I want to use relays, to take the load off the old switches. The column switches are electrically isolated from the body, so I believe they can be used for either polarity. I've gone through and completely refurbished the switches, cleaned every contact, changed every plug and wire as well. Quote Link to comment Share on other sites More sharing options...
NewZed Posted April 24, 2023 Share Posted April 24, 2023 The two switches on top of the steering column are the ones that have problems. You're right it doesn't matter much which side you choose as long as you take the load off of the switch. I did the headlights and the running lights on my 76. The headlights were easy, right by the fuse box, but I had a hard time finding easy access to the supply wire for the running lights. Seems like you're thinking right. Study the circuits though to make sure you're not missing something. Not sure what year you're working on. Nissan changed things up over the model years. 1976 headlights. Quote Link to comment Share on other sites More sharing options...
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