Anto
10-12-2006, 06:39 PM
So i'm having a little trouble reading and decoding the ECU pin diagram in the FSM. I also lack the background knowledge and familiarity of the ECU harness pinout to actually proceed any further without risk of major damage.
Car: 1993 240sx Coupe. OBD1 DOHC ECU.
Okay, upon seaching, I came across this (http://www.240sx.org/faq/articles/95_ecu_pinout.htm) diagram. It's specific for a 95 ECU, and i've read that the older 91-94 OBD1 ones are NOT compatible with the newer OBD2 ones. Of course.
But does that mean the existing pinouts are COMPLETELY rearranged?
What i'm trying to find out is the EXACT function of pin numbers 38 B/R and 113 R - Switched ECU power and Constant ECU power.
First off, are those locations the same on a OBD1 ECU?
Second, What EXACTLY are the roles of constant and switched power?
My Guess: Constant ECU power holds "learned" settings, clock, a/f curve, etc.
Switched ECU power controls everything else, (distributor, camshaft sensor, o2 sensor, A/C system, blah blah blah).
Correct me if i'm wrong.
Now if this is true, would I be able to wire an interrupt switch to the switched ECU power? A sort of killswitch, if you will?
I'm ASSUMING that if the ignition was turned with the power interrupted, nothing would blow or happen. Correct?
Comments are appreciated.
Car: 1993 240sx Coupe. OBD1 DOHC ECU.
Okay, upon seaching, I came across this (http://www.240sx.org/faq/articles/95_ecu_pinout.htm) diagram. It's specific for a 95 ECU, and i've read that the older 91-94 OBD1 ones are NOT compatible with the newer OBD2 ones. Of course.
But does that mean the existing pinouts are COMPLETELY rearranged?
What i'm trying to find out is the EXACT function of pin numbers 38 B/R and 113 R - Switched ECU power and Constant ECU power.
First off, are those locations the same on a OBD1 ECU?
Second, What EXACTLY are the roles of constant and switched power?
My Guess: Constant ECU power holds "learned" settings, clock, a/f curve, etc.
Switched ECU power controls everything else, (distributor, camshaft sensor, o2 sensor, A/C system, blah blah blah).
Correct me if i'm wrong.
Now if this is true, would I be able to wire an interrupt switch to the switched ECU power? A sort of killswitch, if you will?
I'm ASSUMING that if the ignition was turned with the power interrupted, nothing would blow or happen. Correct?
Comments are appreciated.