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wiring for solonoid

New User
Posts: 12
Joined: 08/09
Posted: 01/20/13 04:14 PM

o.k. probably ingorant question for someone my age BUT, what what does the iginition post wiring on the solonoid control? when should it be energized, with
switch on, off or acc position? the reason i'm asking is that my starter got stuck in the flywheel-- changed starters, flywheel looked good, changed solonoids, then chahged the ignition switch itself. it will still crank with the ignition wire connected or disconnected from the post.
   thanks for any explanation as to how this is supposed to work. BTY it has electronic ignition.  Thanks Confused  

Post Reply
Posts: 455
Joined: 04/12
Posted: 01/20/13 09:17 PM

first....  there has been a BATCH of DEFECTIVE starter solenoids floating around...

both plug in wires disconnected....   S  and   I    

when you hook up the battery the ENGINE SHOULD NOT crank...

if it does.. then remove the solenoid and return it..

if not... post that info.. i will be putting together some more info ...  

Post Reply
Posts: 455
Joined: 04/12
Posted: 01/20/13 11:05 PM

i cobbled this together..

Mustang Starting System5  

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Posts: 343
Joined: 11/09
Posted: 01/21/13 08:25 AM

The extra wire from the starter solonoid supplys full 12v to the ignition coil during cranking only, bypassing the resistor, giving a hotter spark for easier starting, the ignition coils are normally 9V only on pointed ignition systems or the dura spark systems, but are fed with 12V for starting. if you want to test the solonoid, remove the cable going to the starter, and then jumper the S terminal to the positive post of the battery, the other small terminal should have 12v, and the plus side of the ignition should also show 12v even with the ignition off. If the cable to the starter is left on, and the other wire to the solonoid where connected to the positive terminal, then the s terminal where jumpered to  +12v the car would start and stay running even without the key, and would stay running.  

Post Reply
Posts: 1410
Joined: 03/08
Posted: 01/21/13 04:12 PM

wow Wayne, that 's a really good simple start/run circuit representation.

orgponny, the S terminal gets battery voltage from the ignition switch when its placed in the start position. This energizes the starter relay coil which pulls the main contacts closed and initiates cranking.

As a result of the main contacts closing, the I terminal is now energized with battery voltage to give the coil a little extra boost of power on start up. (usually will be 10.5 Vdc or higher and may or may not be 12Vdc dependent on starter amp load)

Once the key is released from start back to run, voltage is removed from the S terminal and the relay coil will denergize which opens the main contacts. This stops cranking and also removes battery voltage from the I terminal. (the I terminal will continue to have the voltage that the coil is seeing from the ign switch run terminal through the pink resistor wire)  

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New User
Posts: 2
Joined: 01/13
Posted: 02/02/13 12:54 PM


Post Reply
Posts: 455
Joined: 04/12
Posted: 02/02/13 09:57 PM


a picture is worth a thousand words..

i grabbed images from all over the place to create that..

i have been gathering parts to create a decent image of real parts and real wires...  

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