Check Engine Light still on...

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Jun 13, 2017 | 06:44 PM

quadracerx

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Intermediate

Joined: Jul 2015

Posts: 40

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From: Graham WA.

Check Engine Light still on...

So I had a check engine light on after I fixed the blown head gaskets... After some advice here and research online...

It lead me to replace the O2 Sensor and Coolant Temp Sensor.... The replacement Coolant sensor I received was a single wire like the factory one except it had a spade connector instead of a round one? I sliced a traditional female spade connector onto the wire...

CHECK ENGINE LIGHT STILL ON... except the car runs for a few seconds before it turns on?

Anybody got any ideas?

Thanks for your help..

Steve

Jun 13, 2017 | 07:41 PM

billschroeder5842

Zen Vet Master Level VII

Joined: Mar 2016

Posts: 5,218

Likes: 1,174

From: Southlake, TX

As mentioned in the other post, jump your A/B port on your ALDL and pull the fault code. You can cross reference it from there.

Jun 13, 2017 | 07:52 PM

don hall

Safety Car

Joined: Aug 2002

Posts: 3,842

Likes: 230

From: SANTA CRUZ CA

You didn't post the year of your vette.....important.

Later C4's (1992 - 1996) had 2 coolant temp sensors.
The analog sensor is located in the passenger side block, and the digital sensor is located in the water pump.

Jun 13, 2017 | 09:03 PM

quadracerx

Thread Starter

Intermediate

Joined: Jul 2015

Posts: 40

Likes: 1

From: Graham WA.

Quote:

Originally Posted by seabright

It is a 1984 Corvette with the factory Crossfire Injection... I have access to a old Snap On MT2500 Code Reader Ill try and use that again and do a scan...

Thanks for the help..

Steve

Jun 13, 2017 | 10:13 PM

quadracerx

Thread Starter

Intermediate

Joined: Jul 2015

Posts: 40

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From: Graham WA.

Quote:

Originally Posted by quadracerx

It is a 1984 Corvette with the factory Crossfire Injection... I have access to a old Snap On MT2500 Code Reader Ill try and use that again and do a scan...

Thanks for the help..

Steve

I just used the Snap On MT2500 Scanner... No codes present... Used to show Coolant temp sensor code... That is gone now... BUT the damn CHECK ENGINE LIGHT goes on after about 5 seconds!!

HELP!! LOL

Thanks again,

Steve

Jun 14, 2017 | 07:44 AM

don hall

Safety Car

Joined: Aug 2002

Posts: 3,842

Likes: 230

From: SANTA CRUZ CA

The following link is very informative. Click on upper left corner to change subjects:

http://www.corvettebuyers.com/c4vettes/ecm.htm

Jun 14, 2017 | 11:43 AM

84XfireAuto

Advanced

Joined: Aug 2014

Posts: 54

Likes: 1

Quote:

Originally Posted by quadracerx

CHECK ENGINE LIGHT STILL ON... except the car runs for a few seconds before it turns on?

Anybody got any ideas?

Thanks for your help..

Steve

I have a stock 84 CFI, and my check engine light would faintly glow after the car ran for about 30 seconds, then glow brightly as the car got to operating temp.

It would then stay on while the car ran.

I tried everything, scanners, the old paper clip trick. No codes, nada.

Then, out of desperation, I tried what some call the "live mode" where you drive the car with a paper clip jumper and watch the check engine light.

Turns out, my car had a lean 02 condition. Odd, since the tailpipes get a bit carboned, but thats another story.
Anyway, I replaced the fuel pump and sender assembly, and it corrected the problem.

Jun 14, 2017 | 02:44 PM

aklim

Team Owner

Joined: Jul 2004

Posts: 28,475

Likes: 3,291

From: Hartford WI

Quote:

Originally Posted by quadracerx

Assuming the MT2500 can read your ECM, I know 85 is out of the question but not sure about 84, can you get data from it? You should be able to see what the ECM sees if it can. While it gives the light, scan it and see if the ECM really sees it or whether it is a ground somewhere.