Lately I've been seeing my "Check Engine" light come on after driving for a half hour or so. It turns off after a while. There doesn't appear to be anything wrong with the operation of the car ('85 Toronado) as all gauges (oil, temp, alternator) are normal, and the car seems to run fine. Of course, when I bring it into the shop the light won't come on so they can't diagnose the problem. Should I worry?

 

They should be able to upload the code causing the light - your car should be equipped with an OBD 1 style connector. If it's only intermittent I wouldn't worry much. I ran into this problem with my wifes car (96 GM) and it ended up being a 'misfire' on the #1 spark plug. I also ended up replacing the front O2 sensor as it was dirty. Have you checked your plugs to see if any of them are fouled?

 

The check engine light monitors many other things that are not part of the oil/temp/alt light system.

As Allan says, a code should be stored whether or not the light stays on. Autozone, for one, will read the code for you for free if you take your car to one of their stores. Even if you don't fix it, you'd at least know what the problem is.

 

Wow! That's a deal in itself. Most of the shops up here charge between 70 and 85 just to hook up the OBD connector and download codes. Then they charge for whatever else is needed. Not like the old days when a diagnostic would be absorbed into the cost of the repair as long as you did it at the same shop.

I'd go for the free diagnostic just for peace of mind knowledge. If it's a minor little thing, I'm sure Autozone will also wipe the codes if requested?

 

As far as I know, all the big chains will lend OBDII scan tools for free these days.
You just leave your license with the counter person and take the tool out to the lot.
If you want to clear the codes, you can clear them. '
The catch is that they may not have tools for anything other than OBDII (such as OBDI, ABS, Airbags, etc.).

A lot of those '80s cars can read out the codes through Check Engine Light flashes, though - if so, it's in the CSM.

- Eric

 

The big chains cannot scan this car the can only do obdII. Actualy being a 85 you can scan it your self with a paper clip. the check engine light will flash the code. It will first flash a long single followed by 2 shorts flashes it will do this 3 times this code says the motor is not running after this the actual problem code will flash 3 times. with the first number being long flashes followed by short flashes for the second number. 36 would be 3 long followed by 6 short each code will repeat 3 times. Sounds like a O2 code since you drive it 30 minutes before it comes on . You will need to jump terminal A and B on the diagnostic connector they are side by side on the connector

 

I used to get that on my 02 cheb pu.
Changed out the gas cap of all things,
haven't seen it back on in over two years, go figure.

 

Deja vu! I noticed that if you don't clik the gas cap MORE than 3 cliks there is a good chance of seeing that stupid light. I stopped, undid the cap and put it back on more than 3 cliks. Light went out in about 2 blocks. Must be something to do with gas tank venting that's also monitored.

 

Thank you all for your tips on solving my problem. I did go to Auto Zone to have them check it, but they told me that on all cars older than '90 the codes are not stored in memory and can only be read if the light is on at the time. I don't know where to jumper the pins to do it myself, although I could do that if I knew where to locate it. Might just try the gas cap as the one on there is lockable and I didn't get a key for it; you know how that Murphy thing goes!

 

Ah, didn't know that. Sorry for giving you the bad lead.

 

As OldsRallye350 said, just jumper the terminals in the picture he posted:



- Eric

 

I believe our friends at Autozone are wrong again. I have an '83 Delta 88 and check engine codes are stored in memory, even when the light is out. You wouldn't know if the fault is present while testing anyway, because the engine is not supposed to be running when checking. The ignition is supposed to be in the on position, where the idiot lights come on steady, engine off. Check engine light will also be on. Just jump out those two points A and B shown on that diagram and it will begin to flash the codes. Each one repeated three times. At the end it will again flash code 12 three times.

 

Good point! I hadn't even thought of this.