service engine soon light
Team Owner
Joined: Oct 2000
Posts: 96,443
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From: Fort Knox, KY
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For GM domestic vehicles made before 1995, the diagnostic connector is located under the dash panel by the driver side.
To get the check engine codes to flash in your dash panel, use a jumper wire or a paper clip and connect terminals A and B of the diagnostic connector. Turn your ignition key on with engine off and the codes should start to blink.
All codes should start with code 12 which is one long flash followed by 2 short flashes. This code 12 means the diagnostic system is normal and will repeat itself continuously if there are no trouble codes. Otherwise, code 12 will flash 3 times before flashing the fault codes.
Counting the codes being flashed is almost the same for these 3 domestic vehicles and most of the codes can be erased or cleared by disconnecting the battery negative terminal for 1 minute and reconnect.
Just make sure to check your service manual in case you have electronic equipment such as radio or clock that needs reprogramming in which battery disconnection is not recommended.
Finally, after performing repairs on the culprit code, always go for a road test to confirm if the problem is fixed.
To get the check engine codes to flash in your dash panel, use a jumper wire or a paper clip and connect terminals A and B of the diagnostic connector. Turn your ignition key on with engine off and the codes should start to blink.
All codes should start with code 12 which is one long flash followed by 2 short flashes. This code 12 means the diagnostic system is normal and will repeat itself continuously if there are no trouble codes. Otherwise, code 12 will flash 3 times before flashing the fault codes.
Counting the codes being flashed is almost the same for these 3 domestic vehicles and most of the codes can be erased or cleared by disconnecting the battery negative terminal for 1 minute and reconnect.
Just make sure to check your service manual in case you have electronic equipment such as radio or clock that needs reprogramming in which battery disconnection is not recommended.
Finally, after performing repairs on the culprit code, always go for a road test to confirm if the problem is fixed.
Pro
Joined: Mar 2008
Posts: 579
Likes: 2
From: High Bridge New Jersey
Most
You can either find someone who has the reader for the older models, pick one up online for not a lot of $, or do a search or consult the FSM for detailed instructions on manually 'jumping' the ALDL leads under the dash to generate the codes.
Instructor
Joined: Aug 2008
Posts: 114
Likes: 0
From: Oceanside Ca.
I have the same problem on my 91.Light go's out after the car warms up.My guess is a loaded O2 sensor.My owners manual even says to hold the car at 2000 rpms for 2 minutes to clear it out.It works.
Last edited by Sparkostatic; May 26, 2009 at 11:54 AM. Reason: picture
