Semi-explanation of how relays work - Honda Prelude Forum

Ludatic · 03-30-2003, 01:48 AM

i'm sure some of u know and some of u don't know how relays work.. so imma give an explanation

and ur probably wondering why i'm posting this, well because i still have a few questions about it myself..

but anyway here goes..

lets say we're powering the headlights, and that they require a ****load of power.. (i'm just making up numbers here), lets say it needs 1000 amps, and that the headlight switch, can only withstand 50 amps.. (yes exaggerated but i'm just using this so some of u can get a better understanding). ok so the headlight is already grounded with one prong, but the other prong needs to complete the circuit.. so what do u do, you wire it to a 12v source, the battery.. but u want to be able to turn the headlight on and off, u put a switch between the battery and the headlight... so what happens when u turn the switch on? BOOM too much current, 1000 amps when ur switch can only withstand 50... now how do u avoid that?

a relay.

lets take a 4pin relay
pin 1=in from constant (ur battery)
pin 2=in from switch
pin 3=out to ground
pin 4=out to headlights

how does this work?
well when u activate the switch, a very low current signal is sent througuh pins 2 and 3... when 2 and 3 are connected, it causes an electromagnet to connect pins 1 and 4...

basically the switch activates a tiny thing, which in turn activates a bigass thing..

so now the headlights are being powered straight from the battery (through the relay of course), and ur switch is only powering the electromagnet in the relay.

now lets take the accord trunk popper for example.
the accord trunk popper is grounded with the harness... then it has a wire sticking out, which requires a positive signal.. and u run that to the front of ur car.. but u can't run it straight to the alarm brain. the alarm brain sends off a NEGATIVE (ground) signal... AND its low-current.. so what do u do? u get a relay.

pin 1=in from constant
pin 2=in from another constant
pin 3=out to alarm brain
pin 4=out to accord trunk popper

so basically, when u activate the option button on ur remote.. ur alarm brain sends a negative signal, or if u wanna say, it grounds that wire... and since pin 2 has a constant source, pin 2 and 3 complete the circuit, thus causing pin 1 and 4 to connect, so bam, constant from pin 1 powers the accord trunk popper!

ok so now that i've explained this all, here's my stupid question:
on the relays of the accord trunk popper and jdm fogs.. it's a 4-pin relay.. BUT, it also has a metal plate where u mount the relay.. and ppl say u "must" mount it somewhere metal so it grounds itself... so technically, if that metal plate is the ground, then u have an extra pin.. so what the hell does it do?? my guess is that u dont really need to ground it, or its a safety feature? maybe its just there so u can mount it.. *shrug*

yea yea, ttiwwop

Ludatic · 03-30-2003, 01:51 AM

oh ghey, www.howstuffworks.com already has an explanation..

mehh

oinkus · 03-30-2003, 01:55 AM

haha i guess u're bored

jon i saw on your car that u wired the turn signals to stay on...my question is "was it hard to do?"

godfather16 · 03-30-2003, 02:03 AM

Very Helpfull fact to know.................

Turn signals to stay on?????
Simple.Go buy a double filament bulb and a dual socket, simple wiring and you're done!
I have it on mine.....

Ludatic · 03-30-2003, 02:37 AM

actually oinkus, i dont like that "turn signal stay on" mod.. i have JDM FOGS hahahaha =-P

Ludatic · 03-30-2003, 02:45 AM

but oinkus, thie topic about the turn signals has been discussed a few times... do a search u'll find it.. i think the dual filament way is the way to go.. the use of relays is too messy.. too many wires.. with the dual filament method u can just tap a few wires

oinkus · 03-30-2003, 01:50 PM

thanks....gonna search and think about it..

oinkus · 03-30-2003, 01:55 PM

Quote:

Originally posted by Ludatic
actually oinkus, i dont like that "turn signal stay on" mod.. i have JDM FOGS hahahaha =-P

ahha i know u have jdm fogs but i thought u got your turn signals on too

maybe i was seeing things

khilgers · 03-30-2003, 02:17 PM

thanks for the info

godfather16 · 03-30-2003, 04:34 PM

Since I do not have JDM fogs, this mod is perfect for those poor luders...ahahahaha.....

Also I was gonna go the relay way of wiring but as Ludatic said, wiring is a hassle!

vipastyle · 03-30-2003, 05:06 PM

good info about relays

Ludatic · 03-31-2003, 12:10 AM

ttt, can anyone answer my question

crashandburn · 03-31-2003, 12:55 AM

Use a DMM to map out the internals of the relay, including any possible electrical connection to the mounting plate. You should see some DC resistance across whichever two terminals are the coil.
Are those relays supposed to be single-throw (coil makes or breaks connection between two terminals) or double-throw (coil on or off selects which of two terminals a third terminal connects to)? A double-throw relay would be a five terminal device -- power and return for the coil and three terminals for the switch. Maybe the mounting plate is the fifth terminal...

Ludatic · 04-01-2003, 01:40 AM

Quote:

Originally posted by crashandburn
Use a DMM to map out the internals of the relay, including any possible electrical connection to the mounting plate. You should see some DC resistance across whichever two terminals are the coil.
Are those relays supposed to be single-throw (coil makes or breaks connection between two terminals) or double-throw (coil on or off selects which of two terminals a third terminal connects to)? A double-throw relay would be a five terminal device -- power and return for the coil and three terminals for the switch. Maybe the mounting plate is the fifth terminal...

hmm, thanks for the answer... i dont really care about it that much to the point where i'll go and take apart all that **** just to test the relay

o well thanks for the answer

crashandburn · 04-01-2003, 07:45 PM

Oh, didn't know it was already installed. Yeah, if it's working good you should only take it apart if you're going to add LEDs to it.

ludestarbai · 05-15-2008, 08:25 AM

Quote:

Originally Posted by Ludatic

but oinkus, thie topic about the turn signals has been discussed a few times... do a search u'll find it.. i think the dual filament way is the way to go.. the use of relays is too messy.. too many wires.. with the dual filament method u can just tap a few wires

ok so i know this thread is old but perhaps someone is still around who's tried this the double filament route...

where can we get a a double filament socket? would it fit in the original location for the bumper lights? i'm assuming you hook up one fillament to whats already there and then tap the other part of the light for the 2nd fillament?

any pics or other infomration regarding it would definitly help.

Thanks!

Ludatic · 05-15-2008, 08:59 PM

Quote:

Originally Posted by ludestarbai

ok so i know this thread is old but perhaps someone is still around who's tried this the double filament route...

where can we get a a double filament socket? would it fit in the original location for the bumper lights? i'm assuming you hook up one fillament to whats already there and then tap the other part of the light for the 2nd fillament?

any pics or other infomration regarding it would definitly help.

Thanks!

double filament socket would be 7443, like our prelude brake lights. You can probably find a 7443 socket at a autoparts store and combine it with the quarter-turn mount of our stock turn signal

if it doesn't fit return it =-P