Starter Solenoid

[donald1950]

Bruce & Ross, i have a NAPA "ignition and electrical system illustrated parts guide" parts book dated sept 2001 and so the parts number is accurate. the "I" terminal goes to the coil to provise momentary 12v to the coil to compensate for the reduction of voltage due to starter draw. back in the day we called it "12v start" and simpaly momentary bypassed the resistor with full 12v to the coil to aid in better starting. both the ST53 & ST56 have insulated base. the ST53 is designated as 37-50 ford trucks & 38 to 53 ford cars and the ST56 is designated as " for 12v systems" and is universal with the ford one wire grounding start button, same basic operation as the ST 53 6v solonoid, just 12v.

Ross many of the 12v solonoids in the book are just as your illustration that requires a 2 wire starter button that supplys 12v to energize the energizing coil in the solonoid as the energizing coil is grounded to the solonoid base.
the ST56 is the only one that is the same as the origonal ST53 except for being 12v.

don

 

[Bruce Lancaster]

There's a reason it works the same...in my older NAPA illustrated guide, from 1977, its origin is explained:
It is listed as crossing over to 59B-11450, which is the general replacement for early Ford buses, 12V vehicles from the Ford factory.