View Full Version : Fried '94 SC EEC, pics inside. What replacements are compatable?

12-08-2012, 01:08 AM
My '94 SC automatic, started bucking (Tach would drop) and trans was shifting wierd, it finally stalled and would not restart. While trying to restart I smelled a hot electical smell from my EEC (Had it laying out on the floor). Quarterhorse was NOT installed at the time. The car is 100% stock, so it runs fine on stock chip. When you turn the ignition on the fuel pump and radiator fan run constantly.

So I got a tow home, and found this when I took the EEC apart (see attached picture). Any idea why this happened?

Big question, my '94 Auto EEC has part number F4SF12A650GB.. Advance Auto says they have a F4SZ12A650GB replacement for an automatic transmission '94 SC. Are these two units compatible?

Thanks for any help,


12-08-2012, 02:52 PM
Jeramie, the R1 resistor failed no doubt due to high current in that circuit in which it's in series. A short somewhere in the circuit would be a likely culprit. It's unlikely for a resistor to fail in that manner of its own accord, i.e., due to simple failure of the component. When a resistor fails in this fashion it typically goes 'open', meaning it interrupts the circuit. If this issue occurred at the same time the fan began running constantly, you might surmise this circuit is involved in regulating the fan, i.e., turning it off and/or on. Purely a guess.

I would examine anything associated with the electronic parts that were laying loose when this issue presented itself, i.e., see what wires or terminals might have brushed up against other metal or wires/terminals so as to determine what might have shorted-out, presuming a current-bearing circuit did touch something it shouldn't have...

I have no 'wisdom' about the EEC itself. Sorry. Hope the rest of this helps some...


12-08-2012, 03:20 PM
Typical failures are caused by Overheating the circuit either due to low resistance or a short along the electrical circuit.

The part number is the same except for the F and the Z .. the Z indicates its a "specialty or aftermarket part" .. its the same part.

You could always try to replace the resistor by itself but without knowing what caused it to overheat and break you may have a repeat failure.

- Dan

12-08-2012, 05:12 PM
if that doesn't work I have a 94 SC automatic ecu thats been laying in my pile of parts for a few years now for 20 bucks.

12-08-2012, 10:34 PM
Thanks for the thoughts guys.. I borrowed a local guys EEC from his '94 SC while his car is apart to rebuild his engine. It is the JC calibration (late 94 and '95) But it works fine. Mine was the early '94 GB calibration.

The JC calibration seems to have much better torque converter lockup logic, it doesn't bog the motor in 2nd gear like the GB cal does. I'm gonna try to pull the JC cal through the quarterhorse and see what the differences are.

if that doesn't work I have a 94 SC automatic ecu thats been laying in my pile of parts for a few years now for 20 bucks.

I will take you up on that offer man! I'll send you a PM shortly.