Diodes
More Turbo
Joined: May 2014
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Why are you trying to prevent back feeding from the starter? Diodes are basically one-way check valves for current.
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Joined: Jan 2001
Posts: 56,992
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From: Virginia
Solenoids spec'd for the later model vehicles should already have the diode built in.
Here' some info on it.
https://en.wikipedia.org/wiki/Flyback_diode
This one should be plenty big enough.
https://www.radioshack.com/products/3-amp-400v-diodes
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Fleet Mechanic
Joined: Jan 2004
Posts: 1,683
Likes: 1,471
From: Mendon, Massachusetts
Thanks for the info, my Mallory Unilite distributor module crapped out on me recently, after doing some research on why this could happen, one reason was voltage spikes from relay coils (not good for electronic stuff like ignition modules........I have a 49 F1 truck and the only relays are for lights, accessories, starter and horn relay (would same 3amp200V diode work with the horn?). The relays for lights & acc. only draw 200ma so I'm using 1N4004 diodes.
Thanks
Thanks
More Turbo
Joined: May 2014
Posts: 642
Likes: 12
Thanks for the info, my Mallory Unilite distributor module crapped out on me recently, after doing some research on why this could happen, one reason was voltage spikes from relay coils (not good for electronic stuff like ignition modules........I have a 49 F1 truck and the only relays are for lights, accessories, starter and horn relay (would same 3amp200V diode work with the horn?). The relays for lights & acc. only draw 200ma so I'm using 1N4004 diodes.
Thanks
Thanks
Moderator
Joined: Jan 2001
Posts: 56,992
Likes: 2,741
From: Virginia
There can be a few things in the circuit when in start. The ignition system for one thing, you need spark for it to start when cranking. The fuel system if it has electric pumps. And usually the computer is hooked into the fuel system in some form or fashion.
I have actually got shocked on the old chrome aftermarket steering wheels with the chrome metal button. When I let up on the button I got a zap from the coil of the horn relay.
I have actually got shocked on the old chrome aftermarket steering wheels with the chrome metal button. When I let up on the button I got a zap from the coil of the horn relay.
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Fleet Mechanic
Joined: Jan 2004
Posts: 1,683
Likes: 1,471
From: Mendon, Massachusetts
Could have been the alt. or reg. not sure how to track down any voltage spike issues from the charging circuit, all voltage checks done show normal readings, my grounds and connectors are clean and secure as well. I have installed a Mallory Circuit Guard between the coil and ignition module to stop voltage spikes......so far so good! Thanks guy's for your input.
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19fifty4
1948 - 1956 F1, F100 & Larger F-Series Trucks
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Nov 5, 2013 07:58 AM
