This is on the '89 IROC in the sig.

I read in the FAQ about how to read codes from the computer using the flashing SES light. I decided to give it a try; first I tried to short pins 6 and 12, and then I tried 5 and 6. Each time after I shorted some pins and turned the key, I didn't get any flashing lights at all. Everything just happened like I didn't short anything at all--I could hear the fuel pump come on, and the "Fasten Seat Belts" and "Security" lights came on, and then went off.

I should note that this car has a Viper alarm system installed in it, and I can tell under the steering wheel where there has been a lot of (messy) electrical work. I don't know why any part of that alarm system would tap into the diagnostic circuit, but I just thought I'd mention that.

Any ideas why I can't pull any codes? Is there anything that I can check with a standard multimeter to see if the diagnostic circuit is good?

Wiring diagrams are always helpful, too.

Thanks

 

turn the key to the 'run' position without starting the car. if the service engine light still doesn't come on at all - even solid- then replace the bulb.

 

patrickm00: I should have thought of that!

I did what what you said, and sure enough, the light doesn't come on at all. The only lights that come on are the Fasten Belts and the Security lights. My daily driver is an '88 Camaro and it has a SES light but no Security light; I guess I just assumed that the SES light was replaced with the Security light in '89 (what is that security light for, anyway?).

Hopefully it's just a bulb, and hopefully I won't have to dig too deeply into my dash to replace the bulb.

Thanks

 

the security light is for VATS

Quote:

Hopefully it's just a bulb, and hopefully I won't have to dig too deeply into my dash to replace the bulb.

nope, it's not that big a deal. just a few screws for the dash pad, then a few more for the plastic panels.

 

Well, I got the gague cluster cover panel off. It was just eight screws around the perimeter--didn't even have to remove the dash pad. Turns out, there wasn't even a bulb in the SES socket.

 

that's always a sign of a well-cared for car and a conscientious seller...

 

There may have been a reason for that; see here .