5 terminal HEI module

[dzorde at aesprodata.com.au]

     Thanks John,
     
     With the 5-pin module essentially breaking the pick-up to coil driver 
     connection, this would be ideal for replacing the esc module with an 
     aftermarket ecu for the timing.  Just need to modify the pick-up wheel 
     I think (need to examine the ecu instruction manual to see what is 
     suggested).  
     
     Do you know how processed the pick-up signal is when it goes to the 
     esc module ?  and do you know what signal the esc module uses to drive 
     the coil driver in the ignition module ? 
     
     I'd hate to start to try and fit a big tooth wheel and pick-up as well 
     as coil driver to connect the ignition side of my ecu, if I can simply 
     use a 5-pin module (and maybe some filtering) to do the job.
     
     Dan        dzorde at aesprodata.com.au 


______________________________ Reply Separator _________________________________
Subject: 5 terminal HEI module
Author:  diy_efi at coulomb.eng.ohio-state.edu at INTERNET
Date:    10/21/96 9:25 PM


dzorde asks about the function of the 5 terminal HEI module. This was an 
early control system for knock control only. The distributor (dizzy?) still 
had centrifugal weights and a vacuum advance.  The positive line of the two 
wire pickup coil is sent to an ESC controller, instead of going right to the 
HEI module as in the 4 terminal variety. If the ESC controller is not 
detecting any knock input it simply allows the pickup coil signal to return 
to the module and fire the coil. If it does detect knock, it DELAYS the 
return of the pickup coil signal for a time equal to the numbers of degrees 
of retard it commands, based on a lookup table in the ESC controller. The 5th 
terminal is simply used as the line to return the pickup coil signal on. It 
was an early, rather crude method of knock retard, but was perceived as a 
great accomplishment at the time. I make this assumption based on the size of 
the "ESC" emblem they used to put on the tailgate of trucks equipped with 
this system. When I am doing a repair on these systems, most customers allow 
me to just loop the positive pickup coil wire back into the module and throw 
the ESC controller away!
     
                John Spears 
Speartech Fuel Injection Systems