Starter relay


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By BrianL - 15 Years Ago
Guys,

In another thread I have previously mentioned a no spark condition while cranking. Just got back from a business trip, so got to spend some time checking some things.

I re-wired some of my wiring during the winter as every time I moves some of the old wires, the insulation seems to crack. And I wanted to assure I was getting full 12+V at my Pertronix module (remove the resistor). In another thread I have mentioned I am having starting (no spark while cranking) issues. I measure less than 12V at the positive terminal (my DVM is jumping around, but is definately not coming up to 12+V) at my + terminal on the coil when cranking. I do measure 12+ volts at the coil when the switch is in the ON position. I rememember while researching that Ford ran a full 12V to the coil while cranking to aid in starting, & had an alternate circuit that included the resistor for less that 12V while ON. So I took out my resistor but have apparently also distupted the 12V at the positive terminal at the coil while cranking. I am thinking that I can tap 12V off the starter relay (I have the 4 terminal kind: Large terminal from the battery, two small terminals where the one nearest the battery terminal measures 12V while cranking, another small terminal, & the large teminal that goes to the starter). Does tapping off that 12V while cranking terminal direct to the coil + terminal make sense to you guys? I wanted some confirmation or advice before proceeding.

Thanks,

By Hoosier Hurricane - 15 Years Ago
For years it seems everyone states that the bypass circuit on the Ford solenoids supplies 12 volts to the coil while cranking.  But it is a rare battery that has enough power to maintain 12 volts while cranking.  If battery voltage drops to less than 12 volts while cranking, there is no way it can supply 12 volts to the coil.  Therefore, it is probable that your bypass circuit is working.  Check the voltage at the battery while cranking, and see if that is the same voltage the coil is receiving.
By BrianL - 15 Years Ago
Yesterday I had time to try running a wire directly from the solenoid "I" terminal to the + terminal on the coil, and now have spark while cranking. Thanks to Greenbird56 for a wiring diagram as that gave me the clue I was missing. I wanted to post a follow up in case someone has similar troubles in the future.