Just joined? Please introduce yourself.
Results 1 to 8 of 8

Thread: Everything you wanted to know about RELAYS...

  1. #1
    Registered Member WagonCrazy's Avatar
    Join Date
    Mar 2012

    Member #:530
    Location
    Santa Clarita, CA
    Posts
    1,795

    Everything you wanted to know about RELAYS...

    I have now wired up 2 old cars pretty much from scratch, and fumbled my way around wiring systems on other vehicles. i self learned alot about how the power moves thru circuits (and when it doesn't move thru them as intended).

    I found this article recently, and it contains some simple truths about how automotive relays work. You guys might find it helpful too...
    https://www.hagerty.com/media/opinio...2871acb8db3597
    1957 Nomad- LS1/T56 on C4 chassis
    1959 Fleetside Apache 1/2 ton, shortbed, big window, 327ci.

  2. #2
    Registered Member NickP's Avatar
    Join Date
    Mar 2012

    Member #:1653
    Location
    De Queen, AR
    Posts
    4,157
    Thanks for sharing

  3. #3
    Registered Member chevynut's Avatar
    Join Date
    Nov 2011

    Member #:115
    Location
    Fort Collins, CO
    Posts
    10,844
    There is one thing to watch out for and he eluded to it. Generally, you can swap terminals 85 and 86 but some relays have diodes in them to protect the driving circuitry. If you wire it backwards, the diode will conduct and the relay won't operate. If you always make 86 the positive side, you'll be ok. He talked about terminals 30 and 87 and that they might have diodes on them, but I've never seen one like that.
    56 Nomad, Ramjet 502, Viper 6-speed T56, C4 Corvette front and rear suspension


    Other vehicles:

    56 Chevy 2-door BelAir sedan
    56 Chevy 210 4-door sedan
    57 Chevy 210 4-door sedan
    1962 327/340HP Corvette
    1961 Willys CJ3B Jeep
    2001 Porsche Boxster S
    2003 Chevy Silverado 2500 HD Duramax
    2019 GMC Sierra Denali Duramax

  4. #4
    Registered Member WagonCrazy's Avatar
    Join Date
    Mar 2012

    Member #:530
    Location
    Santa Clarita, CA
    Posts
    1,795
    Laszlo,
    I'm circling back to your comment:
    Generally, you can swap terminals 85 and 86 but some relays have diodes in them to protect the driving circuitry. If you wire it backwards, the diode will conduct and the relay won't operate. If you always make 86 the positive side, you'll be ok.
    Take a look at this dual fan wiring diagram posted on Griffin Radiators website.

    The 12v side is the orange wire-pin 85, and the ground side is the grey wire-pin 86. So do they have this backwards from what you are suggesting?(regarding diode's in the circuit)?

    Screen Shot 2024-03-27 at 11.47.32 AM.png
    1957 Nomad- LS1/T56 on C4 chassis
    1959 Fleetside Apache 1/2 ton, shortbed, big window, 327ci.

  5. #5
    Registered Member chevynut's Avatar
    Join Date
    Nov 2011

    Member #:115
    Location
    Fort Collins, CO
    Posts
    10,844
    Quote Originally Posted by WagonCrazy View Post
    The 12v side is the orange wire-pin 85, and the ground side is the grey wire-pin 86. So do they have this backwards from what you are suggesting?(regarding diode's in the circuit)?

    Yes, it's backwards from conventional wiring procedures where 86 is positive. However, as long as the relay doesn't have a diode in the coil circuit between terminals 85 and 86 it will work fine. Some relays do and some don't. Like I said if you always wire 86 to + you should never have a problem.

    https://www.hagerty.com/media/mainte...relays-part-3/

    https://www.youtube.com/watch?v=7nrDeQRTCm8

    https://www.12voltplanet.co.uk/relay-guide.html
    56 Nomad, Ramjet 502, Viper 6-speed T56, C4 Corvette front and rear suspension


    Other vehicles:

    56 Chevy 2-door BelAir sedan
    56 Chevy 210 4-door sedan
    57 Chevy 210 4-door sedan
    1962 327/340HP Corvette
    1961 Willys CJ3B Jeep
    2001 Porsche Boxster S
    2003 Chevy Silverado 2500 HD Duramax
    2019 GMC Sierra Denali Duramax

  6. #6
    Registered Member WagonCrazy's Avatar
    Join Date
    Mar 2012

    Member #:530
    Location
    Santa Clarita, CA
    Posts
    1,795
    Got it. Wanting to know what the correct methodology is and you've covered that.

    So a 12v relay with a diode would probably have a marking on it like this symbol?
    Relay with diode.jpg
    1957 Nomad- LS1/T56 on C4 chassis
    1959 Fleetside Apache 1/2 ton, shortbed, big window, 327ci.

  7. #7
    Registered Member chevynut's Avatar
    Join Date
    Nov 2011

    Member #:115
    Location
    Fort Collins, CO
    Posts
    10,844
    Quote Originally Posted by WagonCrazy View Post
    So a 12v relay with a diode would probably have a marking on it like this symbol?
    Exactly. The arrow on the diode shows the direction that the current will freely travel. It won't travel in the other direction. It's like a "check valve".
    56 Nomad, Ramjet 502, Viper 6-speed T56, C4 Corvette front and rear suspension


    Other vehicles:

    56 Chevy 2-door BelAir sedan
    56 Chevy 210 4-door sedan
    57 Chevy 210 4-door sedan
    1962 327/340HP Corvette
    1961 Willys CJ3B Jeep
    2001 Porsche Boxster S
    2003 Chevy Silverado 2500 HD Duramax
    2019 GMC Sierra Denali Duramax

  8. #8
    Administrator 567chevys's Avatar
    Join Date
    Oct 2010

    Member #:3
    Location
    Woodland Washington
    Posts
    2,416
    Good information ,

    This is a Site I used when I was younger it hasn't been updated in a long time but basis good information

    http://www.madelectrical.com/electrical-tech.shtml

    1955 2 DR Post
    1937 Chevy Coupe
    2023 Ford Super Duty F350 TREMOR
    2019 Corvette Z06
    1955 Chevy Nomad
    1935 Ford 2dr Slant back I have 4

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •