HELP? Q: Reading computer codes in Chevy

[Jay G.]

Ok, so I made the mistake of installing some lights for a friend in his 2000 Chevy Cavalier. I had to disconnect the battery to hook up the accessories. Since then, he is intermittently getting the check engine light on. I know there was a way in some cars to read the computer without the real tools by using some kind of jumper. Is this still true?? HELP! I want to either read it and find out what the code is or just clear/bypass it?

thanks!

[JAYMZ]

Some cars have a way to reset it by tapping the brake pedal or something a certain amount of times to reset certain things. Otherwise it'll need a code reader to clear them out. If you know a mechanic that has one you might be able to talk him(or her) into clearing the codes for you. If not take it and have the diagnostics run on it. When hooking up the lights you might have caused a surge and fouled something up. Or just plain old gave the computer enough of a zap to make it go screwey.

But if the light is intermittent and the car is running ok....if your friend doesn't mind have him wait until the next servicing he gets to have it checked. Cavaliers are pretty decent cars...hard to kill...I wouldn't worry too much if it runs ok still.

[Bob]

Don't know if they're doing it on the new Chevys. On my 1992 Blazer, all you had to do was jumper two of the contacts on the diagnostics connector block just above the brake pedal. I think there was a combination of key turns that you needed to do along with it.

Go to your local library and see if they have an updated Chilton's manual for the car. In the absence of that, many of the larger auto parts places have repair manuals for most vehicles. One of the first things I do when I buy a new vehicle is go out and buy the repair manual for it.

[elkbow]

I would pick up the manual, haynes or other, it will have instructions on reading the codes and some on how to reset lights. My nissan is simple and uses a series of flashing lights to give the codes.

[Threeshot223]

A 2000? You'll have to take it to a place like Autozone to have the codes read. 1996-and later vehicles use an OBD-2 computer control system- these are only readable by diagnostic scanners (code readers).

And...you say intermittent. Is the battery cable 100% back on? Did you clean the cable end before you reinstalled it? Enough corrosion can form on battery contacts so that you would get intermittent power failures that you dont notice, but the computer does.

[jim]

Any 96 or newer vehicle needs to be reset with an OBDII compatible scanner. If it's a proprietary GM code (not generic), you'll need a GM/MasterTech scanner to do this.

Did you install strobes? Chances are, you may have an EMI problem from the 4KV trigger signal. MAke sure the POWER SUPPLY END of the cables have their shields grounded solidly to the chassis. Don't use crimp junk either- solder them.
EMI will wreak havok on a PCM, ABS, SRS and other vehicle computer systems.

[Jay G.]

Thanks to all for the many replys. Turns out - it was the "service soon" light that was coming on when the headlight flasher was on. The car sees a missing bulb and turns on the light!

Thanks to all for the help!