Check Engine Light on 1982 Avanti II

[CBS Avanti]

I am relatively new owning this Avanti II, or any Avanti for that matter. It came with a battery isolation switch on the negative battery post to prevent a phantom drain. It came with a Sears 2-year battery. God knows how long it had been in the car. I have a new one now.

When I fire it up, the Check Engine warning light comes on. Because of the age of the car, the documentation on why it came on doesn't exist... or let's say, I can't figure it out.

Does any body here have any ideas what may be the issue?

Thanks,

CBS

[mfg]

1 hour ago, CBS Avanti said:

I am relatively new owning this Avanti II, or any Avanti for that matter. It came with a battery isolation switch on the negative battery post to prevent a phantom drain. It came with a Sears 2-year battery. God knows how long it had been in the car. I have a new one now.

When I fire it up, the Check Engine warning light comes on. Because of the age of the car, the documentation on why it came on doesn't exist... or let's say, I can't figure it out.

Does any body here have any ideas what may be the issue?

Thanks,

CBS

Your Avanti has what GM Called “Computer Command Control System”

That check engine light is part of that (emissions) system.

It should go off a few seconds after you start the engine…..If it stays on, it does not mean there is an engine problem… The light staying on indicates a problem in your Avantis emission system… which could be a multitude of items.

There’s a plug under your dashboard that a code reading device can be plugged into which may zero in on the issue.

[CBS Avanti]

Thanks..... where does one find a code reading device?

[ronmanfredi]

Since it's not an OBD2 computer system, the standard code reader won't work.  GM provided a self diagnostic method where you can jump 2 pins in the diagnostic plug and then the dash light will flash in a pattern for each code.  If you google the system, you will find instructions and a table that tells you what each flashing sequence means.  If the O2 sensor in the exhaust system is original, you need to change it first since the original one will be worn out. The other thing to look for are loose or corroded connections with the computer system.  I once had one where the main connector at the control unit just needed to be unplugged and plugged back in due to a weak condition.  The CCC system is simple and cheap to fix, just get the warning light codes and go from there.

[CBS Avanti]

Thanks so much for your tips. Gives me an opportunity to crawl around upside down under the dash. 😁  This is giving nasty flashbacks when I owned a 1984 Chrysler convertible with O2 sensor issues. I also had a 1996 diesel Passat that developed electrical problems. Gawd, I hate E-problems. The problem with an old diesel Passat is the motor lasts forever, but the rest of the car ages poorly.... enough of my story telling....

I have had my Avanti's control unit out and in, so a corroded contact is not likely. 

[Skip Lackie]

You should have the OBD1 system, which was used (with updates) all the way through 1995.  There were a number of manufacturers of OBD1 code readers back in the day, and used units should be readily available (cheap) on places like ebay today.  Almost any of them will cover 1982 models.  As noted above, Google will be able to tell you how to get the codes without a code reader by simply jumping across two of the pins on the diagnostic plug.  The CEL will blink a code, like 21, three times.  I use that method to quickly read the codes on my 89 Camaro.  It saves me the trouble of having to re-learn how to properly use the code reader.

BTW. investing in a 1982 Chevy shop manual might be a good idea . . . .