Solenoid on 72 Blazer

[K5Danny]

Over the weekend my solenoid went out on me. This will be my first time replacing one of these things by the way. I crawled under the truck this evening and yanked it out. Maybe there's an easier way, but I ended up dropping the starter for better access to all of the screws. While removing all of the wires, I noticed a yellow wire (pretty sure it was yellow) was frayed and hanging loose and the small left post of the solenoid had a wire connector without a wire. Do you guys know of a wiring diagram for these things, or if that is indeed the right location for that wire?

Thanks in advance!!

Danny

[K5Danny]

Oh, forgot to mention.. I noticed that the starter (at least on my rig) isn't coming out easily if it ever needs to be replaced. I'll have to drop the front driveshaft on mine if it ever needs it.

[K5Danny]

R stands for relay, S stands for solenoid. Solenoid is what is used to power the starter. Relay is used to divert 12 volts to the coil while starting (points systems usually run on 9 volts while running, it makes the points last longer). It only diverts 12 volts to the coil during starting, so that the motor has an easier time of starting.

SO, the yellow wire is supposed to go from the R post to the positive side of the coil.

Purple is the start wire so it HAS TO go to the S terminal.

Ignore what other people are telling you - do not change the wires. Although I am sure there are well meaning people there, usually most people don't that much about how a points system is wired up - because they don't know how it works.

You would be MUCH better off if you convert to an HEI ignition - because the HEI runs on 12 volts all the time (no points to wear out quickly at that voltage

Found this on another forum and it was vehicle specific, so just adding it here for any future reference.

[PD1292]

I have converted mine to an external solenoid, i think it is from a ford product. A friend helped me who is a Chevy only guy, so if he put anything ford on his there has to be a good reason. here are some pictures. The first pictures are from my 70 Chev truck. Ill try to post some from my Jimmy which has not been converted, mabe this will help. I think you will have to repair your starter either way, but this makes some kind of difference, mabe some one else could elaborate on it.
Good luck with it.

[PD1292]

Well I went out to take pictures of the jimmy and found it was too tight to fit my camera into. the small wire is in the same place as the looped wire on my other truck and it comes from the ignition switch, mine is a purple wire though. hope this helps.
barry

[Burt4x4]

I have the Ford remote silly too but mine is wired differnt than PD1292^^
My Chevy silly has a jumper wire going from the 12V batt cable to the S termanal so when the Ford silly trips and makes the batt cable live with 12v the jumper trips the silly alowing the starter to turn.

The reason I did this is to prevent HOT start issues, starter not cranking over when engine bay is hella hot, like wheeling during 100+deg summer or headers too close to the starter.

The idea is NO 12v to the starter until needed. Having a completely "dead" batt cable at the starter is the trick as no resestance can build up on a dead cable.

Heat creates resistance...too much heat on a "live" cable alows for the resistance to get higher and higher = amprage goes lower and lower..then you turn the key wich triggers the silly but not enough "power/current" or amps are present to turn the starter because the live cable's resistance is too high and your current is now low low low.

Keeping the 12V away from the hot starter cable means no build up of resistance cuz the cable is "dead", electrons are "sleeping". When you turn the key (purple wire) the Ford silly trips lets 12V thru and down to the starter via batt cable, freash 12v with all it's power. Vaaaroooom every time!

Happy Friday!!

[K5Danny]

Thanks for the pics and info guys! I about killed my battery trying to crank the Blazer unsuccessfully on Thursday. I hooked my charger up to it after work yesterday and flipped it to the "high amp engine start" option. Turned the ignition switch and the engine fired up instantly. I let the battery charge up for a while and tried cranking without the charger. It was very sluggish to turn over, but cranked. I think I'm going to need a battery with some better cranking amps or maybe this battery is just going bad.