additional ignition, accessory, etc., diode

I know that the general concensus with any additional Ignitions, accessories, starters, etc. is to add a relay, but would it be possible (and of course safe) to simply split the line using diodes? Basically the same as splitting an unlock/lock output. I've never really looked too far into diodes (other than the small 1n4004's for unlocks, etc) so I don't know if they really even make a 15amp or so, but it was something that got me thinking. So whats the general input on this? I think it would help clean up the install a bit since 2 diodes of that size would still be smaller than a relay... and it would be a few less connections to go bad... Opinions???Kenny

Owner / Technician

KKD Garage LLC

Albany, NY 12205

In theory it should work fine if you get a diode that's rated for what you are trying to do. The concern is down the road if a connection fails or needs to be changed for any reason. With a relay, you can leave all the wiring the same, pull the relay, put a new one in and keep moving. With a bad diode, you would have cut it out, make sure you have enough slack on the leftover wire and add the new one in. The cost may be roughly the same as a relay with harness (about $7-10). Otherwise, sounds like a cool idea. You could use something like this. It's rated for 30amps and range from 40-600V

I would assume that would work okay as long as you did not exceed the amerage of say a second accessory wire from your remote start to power up another accessory wire in the vehicle. Alot of the newer vehicles with the smaller guage wires at the switch I  think would be fine.. But some of the older vehicles with some larger guage wiring might want to check the amerage first...just my thoughts!!!!

I figured the hard part would be finding the heavy duty enough diodes... but you also bring up a valid poing about replacing it down the road...Kenny

Owner / Technician

KKD Garage LLC

Albany, NY 12205

I have six amp diodes in my box at work and there about the size of a shallow 10 mm socket . There pretty big. So I can't imagine the size of a 20amp

i use 6amp diodes for vehicles with independent parking lights (such as mitsubishi lancer), and 1amp diodes for other applications. However, IMO for what its worth, i would just use a relay. Im sure for the new toyota vehicles with 20+ gauge at the ignition harness, a 6amp diode could be used for second start, acc, ign.Ted

2nd Year Tier 1 Medical School

Still installing as a hobby...pays for groceries

Compustar Expert

I kinda figured the relay would still be the best bet... but it never hurts to brainstorm... lolKenny

Owner / Technician

KKD Garage LLC

Albany, NY 12205

According to the diagram on the right that nut at the cathode is a 10mm spanner size! Kenny, ask yourself this...why does the manufacturer have two SEPARATE starter wires from two DIFFERENT pins at the ignition.