SES Light on - Team Camaro Tech
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post #1 of 3 (permalink) Old Dec 29th, 12, 04:42 PM Thread Starter
Join Date: Dec 2012
Location: Los Angeles, Ca
Posts: 1
Post SES Light on

I have a 1994 Camaro Z-28; I purchased it with blown head gaskets not knowing how many other things was wrong but over a few weeks an hour at a time I found out.
After I redid the heads, I added a water pump, plugs and wires, radiator, thermostat. I started it and it ran very well but the SES light came on and stayed on. I don't have the tools I use to have for testing so I had to go it the old way.
I did this in hope to help other with an SES light on and off and a failed smog test.
I tested the EGR valve and it was frozen so I installed a new one, $54., I tested the two AIR Valves both were junk so I replaced them but the light stayed on. I removed the AIR Pump and tested it and found the motor was frozen so I took it apart and cleaned it and now it work perfect. I figured if I have to replace it, it won’t matter if it is damaged or not, it was easy to get apart, the engine light went off after this repair.
I went in for smog and got a High HC read out. I went back in and checked the entire vacuum and found one on the EGR to port was backwards, my mistake. I then made sure the intake was clean, I did that when it was off but rechecked it. I checked the Map sensor and cleaned it, I also found the Air Intake tube was not fitting as well as it should so I replace it. The engine ran smooth but had a little tick to it and I knew something was wrong in the ignition system. I pulled the spark plugs and examined each one as I pulled them, I found the #7 was cracked under the gap area and it was jumping fire, I installed another set of plugs and it smooth out. I went back for the smog test and the reading dropped considerable but it did not pass. I checked the cat converter and found it was broken so I replaced it, I went back in for smog and it passed like a new car.
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post #2 of 3 (permalink) Old Dec 29th, 12, 05:17 PM
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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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post #3 of 3 (permalink) Old Dec 31st, 12, 08:50 PM
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Re: SES Light on

we actually used a key like this back in the day ...
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engine, light, power, ses, smog

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