Check Engine Light........
Thread Starter
Race Director
Joined: Jul 2001
Posts: 13,710
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From: So Cal
Check Engine Light........
The past couple of days my check engine light has been coming on when first starting her. Both fans turn on immediately even when the car is cold. The light and fans go off after a few minutes when the engine heats up and the car is fine the rest of the time. No other issues except this. I am thinking that it may be a faulty temp sensor or fan relay, but not sure. What do you all think? Like I said no other problems except this. My car is a 94' auto. with about 95k, any help is appreciated. :seeya
Le Mans Master
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From: DrunkDefender
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St. Jude Donor '07-'10
Re: Check Engine Light........ (morphious)
Pull the codes and let us know what it has stored in it over in C4 tech section.
Heres the proceedure.
Key off.
Take a (bent) paperclip and insert it into the right top two holes in the connector located under the knee bolster so that it grounds the one to the other.
Turn key to ON position but do not start. Fans will turn on if you have done it correctly and the car will then be in field mode. Check engine light will flash a code 12 3 times, then any stored codes. When all codes have been flashed it will then flash a code 12 3 more times indicating it is finished.
Heres the proceedure.
Key off.
Take a (bent) paperclip and insert it into the right top two holes in the connector located under the knee bolster so that it grounds the one to the other.
Turn key to ON position but do not start. Fans will turn on if you have done it correctly and the car will then be in field mode. Check engine light will flash a code 12 3 times, then any stored codes. When all codes have been flashed it will then flash a code 12 3 more times indicating it is finished.
Thread Starter
Race Director
Joined: Jul 2001
Posts: 13,710
Likes: 0
From: So Cal
Re: Check Engine Light........ (Dr. Evil)
Hey Dr, I tried this and the fans came on, but the engine light simply went off, no flashing, nothing :confused: What am I doing wrong? Thanks.
Drifting
Joined: Nov 2000
Posts: 1,428
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From: Jacksonville FL
Re: Check Engine Light........ (morphious)
Morphious, you have to leave the key in the on/run position for the computer to go into diagnostics mode.
Dr. Evil said the rest.
Hope this helps.
Mike.
Dr. Evil said the rest.
Hope this helps.
Mike.
Team Owner
Joined: Mar 1999
Posts: 89,144
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From: Life's tough, wear a helmet.
Re: Check Engine Light........ (morphious)
http://www.c4vettes.com/ecm.htm
"1994 and 1995 C4s also had the OBD-I system but used a 16 pin access connector that would become standard for the OBD-II system used on 1996 and later Corvettes. For 1994 and later models, you will need to recover the codes using a special procedure involving the speedometer and the odometer as explained in the service manual or use a special diagnostic device known as a scan tool."
"1994 and 1995 C4s also had the OBD-I system but used a 16 pin access connector that would become standard for the OBD-II system used on 1996 and later Corvettes. For 1994 and later models, you will need to recover the codes using a special procedure involving the speedometer and the odometer as explained in the service manual or use a special diagnostic device known as a scan tool."
