Re: SES Light on
If OBD1, you can place the ECM into diagnostic mode by shorting Pins A & B together with a paper clip and read the CEL flashes, key on, engine off.
First set of flashes should be flash, space, flash, flash, = 12, ECM okay and ommunicating. fl, fl, fl, space, fl fl, fl would equal 33, and so on.
It should flash each diag trouble code three times per trouble code, then start over with 12 and repeat.
Then go to the OBDI site and find the code problem.
Also during diag mode, the ECM commands the IAC to seat against the port, EGR solenoid open and charcoal purge open. Pull the IAC connector leaving it seated, undo the diag short, start engine and you can set base idle and unplug ECM bypass to set initial timing, or not, since you have a LT-1, but you can set idle, if needed.
After these are done, reconnect everything, pull a battery cable for about 15 seconds, reconnect cable, turn ign on, engine off for about 125 secionds to let ECM set IAC idle, then turn off ign for 10 seconds. Then start engine normally. It will take time and drive a few miles, including WOT for ECM to learn engine parameters for better running. ECM should control idle rpm even with a load/gear selected.
By puilling off battery cable completely resets the ECM.
If the above is not done, ECM will monitor the fault and if not appearing for the next 50 starts, then DTC will be erased.
Welcome to the Club, Pete. Good job in working on your '94 Z28 and to get it to pass CA emissions. You will be nabbed for pictures, just a warning for you.
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