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Thread: Ignition Switch Question ... 12v while cranking

  1. #11
    Registered Member chevynut's Avatar
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    Quote Originally Posted by 55mike View Post
    perhaps I’ll get a new stock-style switch and jump #1 and #2 terminals. As a side note the old switch works just fine, it’s getting that 12v on cranking that’s kicking my tail.
    im pretty sure the ignition switch is just a 4 pole three position switch. I don’t believe your switch is working properly or the solenoid terminal wouldn’t go hot when the IGN2 terminal is shorted to IGN1. I think there’s something wrong with the switch contacts internally. If IGN2 and SOL are shorted together when in off or run then the switch is bad. I’ll post some schematics tomorrow if I can. Happy New Year!!!
    56 Nomad, Ramjet 502, Viper 6-speed T56, C4 Corvette front and rear suspension


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  2. #12
    Registered Member 55mike's Avatar
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    Thank you Chevynut….. I’m looking forward to what you come up with

  3. #13
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    I don't know how you are testing it, but an ohmmeter will tell you how it works and if it works without even powering it up. That's how I checked mine, and I also used a relay for power on and another one for the starter solenoid. The original switch wasn't designed for any additional current which wasn't much when stock. The switch will only have to carry less than 1/2amp using relays can handle 30amps and the switch will last indefinitely.
    Last edited by 55 Rescue Dog; 01-01-2023 at 10:15 AM.

  4. #14
    Registered Member chevynut's Avatar
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    Pretty sure this is how the ignition switch works. Notice that each output terminal is independent of the others. You can short IGN1 and 2 together and SOL isn’t hot when in run mode. That’s why I think your switch is defective.

    FD979A87-33D6-429F-A630-FC8EFD172DB2.jpeg

    Here’s a couple of ways to address it without a new switch.

    AFCD2655-16D1-4065-97C4-B8AE37D49175.jpeg

    093C221C-3B49-4888-87EB-94CB6756A3B8.jpeg


    The first way still uses the switch as a power source. It powers the relay output while in run or start position. The second takes the load off of the ignition switch. You could also run the solenoid off of another relay to take virtually all the load off the switch.
    Last edited by chevynut; 01-01-2023 at 02:38 PM.
    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

  5. #15
    Registered Member 55mike's Avatar
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    Thanks CN.

    Seems like a relay is the way to go

  6. #16
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    Quote Originally Posted by 55mike View Post
    Thanks CN.

    Seems like a relay is the way to go
    You need to figure out how and if the switch works first and foremost before hooking up relays. It's pretty simple to do with a meter if you know how to use one? I could explain if needed.

  7. #17
    Registered Member chevynut's Avatar
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    Quote Originally Posted by 55mike View Post
    Seems like a relay is the way to go
    Whether you get a new ignition switch or not, a relay is a good idea to take the load off the switch. Pretty much all of the switched power in your car goes through the ignition switch to the fuse panel. So the switch will last longer and you won't be dropping voltage across it with the relay, if you use the 2nd schematic I posted where the 12V source doesn't go through the switch.

    If you get a new switch, the diode isn't necessary because the IGN2 and SOL terminals would be independent (I think they're shorted together on your switch based on your symptoms). The diode can be small in this case because the relay coil only draws maybe 1/4 amp and the diode drops 0.7V so you can get by easily with a 1/2W diode, which is available in any electronics supply store like Radio Shack. Don't use a zener diode. This shows the polarity and how the current flows through it....



    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. #18
    Registered Member 55mike's Avatar
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    I’m buying a new Optima battery (old one is over 7 yrs old)… and when I put my meter directly on it, and had a friend crank over the starter the voltage dropped to about 9.5. I reason full volts will help me find the best connection to the relay (trigger). Then I’ll pull power right off the battery (clean) for the Sniper

  9. #19
    Registered Member chevynut's Avatar
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    Quote Originally Posted by 55mike View Post
    I’m buying a new Optima battery (old one is over 7 yrs old)… and when I put my meter directly on it, and had a friend crank over the starter the voltage dropped to about 9.5. I reason full volts will help me find the best connection to the relay (trigger). Then I’ll pull power right off the battery (clean) for the Sniper
    I'm not an expert on batteries but from googling a few sites it doesn't look like 9.5V while cranking means it's bad. It also depends on the type of starter since an geared starter will have less current load. Did you measure voltage directly on the battery terminals, or on the cable clamp?

    A friend of mine has a Sniper on a 502 and he's had nothing but trouble with it. It literally would not shut off and filled his engine with gas three times when they were installing it at a reputable local shop. They had to pull the plugs and drain the cylinders and change the oil three times. They spent a lot of time with Holley on the phone but they weren't much help, but Holley finally sent them a new Sniper. He still had problems with the new one. Once when I was at his place he tried to start it and it wouldn't run. He disconnected the battery connection and re-connected it and it started. I have read that they have a major problem with EMI. He was using some high energy Holley ignition system so they changed it out and he's had no problems since but is still nervous about it happening again. Holley should have done a better job shielding sensitive wires. Just an FYI.
    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

  10. #20
    Registered Member 55mike's Avatar
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    Yes sir, EMI is certainly a “thing” on Sniper. I’m concentrating on how I run the wiring with that fact in mind. Perhaps to this end, using a relay for the Sniper trigger is prudent to insure as clean of a signal as possible. I’m also adding some ground wires etc
    CN thank you for all your help!
    m

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