The 94 has the OBDI connector under the dash. I tried jumping the connector to flash the codes but the check engine light goes off and does not flash. The air pump and coolling fans come on. Do I have to use a OBD I code reader to retrieve the codes on a 94? I can't find one local, going to have to order. So, still no codes as of now to help troubleshoot.

#2. I checked the connector in the attached pic with voltmeter and less than one volt on any of the pins with the key on.

#3 There are 3 wires that are on the ground stud sticking out of the head where the coil and ICM mount to the head. (also visible in the pic attached) I accidentially broke the black wire connection and noticed it sparked. I put a volt meter on it and am getting battery voltage on the wire when it is not grounded. Pulling the fan actuator fuse under the hood will cause the voltage to disappear from that wire. Also, when that wire is not connected to ground, I do find 12 volts on the black wire that is in the ICM wiring connector in the pic below.

I have disconnected every sensor on the engine along with the ECM and I still have voltage on the wire that is going to ground. I can't find anything in the schematics showing where this wire comes from but following it back in the wiring harness, it looks as if it goes directly to the ECM connector.

I first thought that I had a bad ECM but now I am thinking possible bad ignition switch or something. I'm totally confused. Can anyone point me in the right direction?

 

You can't flash codes on 94 and newer. The PCM is OBDI, and you need a scanner to retrieve the codes, those $30 code readers do not work either.

 

Ok, thanks for that info. The scan tool I was looking at was in the $30 range. I have a OBD II Actron but I don't think it will read the OBD I codes. Going to have to research that a little. And after thinking about the trouble shooting I was doing yesterday, I think I was "chasin rabbits". I'm thinking, If the opti is bad and not telling the ECM to fire the coil, I would not see the voltage at the ICM connector.

 

If the diagnostic connector has 12 pins the system is straight OBDI, if it has 16 pins the system is still is OBDI but the connector is OBDII. The first case you need a scanner that can read OBDI, in the second case you still need a scanner that can read OBDI but the scanner needs an adapter cable OBDI to OBDII.

 

Actron 9145 works on my 95Z

 

Mine is a 9180. My brother had a Actron that came with the cable for the OBD I and OBD II. Someone stole his scanner but didn't take the cables, so I am going to get the OBD I cable he has to see if my scanner can read the OBD I system.

 

I've never seen a 1994 but my 95 has an OBD2 connector and uses the same cable as my newer cars

 

like pete says its a obd1 connector with an obd1 ecu. a obd2 scanner will not work or at least it shouldnt. have you tested the opti? i think i gave you the trouble shooting deal outa my book for the ignition, if not let me know and ill post it.

 

Whoo Hooooooo! I fired it up today!!!! It was a bad electrical connection on the coil. The hot wire was broken inside the insulation of the wiring. $20 for a pigtail, 30 minutes of taking off the K&N filter (because I dropped the pigtail and it went in the air tube) 5 minutes of soldering and it is running. temp staying between the 1/4 and 1/2 mark.
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Thanks for everyones input and yes, Craby, those schematics is what I used to troubleshoot.

 

Good to see you found the source. This should be an important thread for people looking at the optispark. There ARE other issues besides the distributor sometimes present.