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11/25/13 11:13pm - Original Message: 'Check engine light will not go off or flash'
stutrac
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Bethany, CT - USA

Vette(s):
1981

Joined: 11/14/2013
Posts: 32
Fuse has power, I tried the paper clip Light does not flash, Checked grounds all good, Cleaned the edge connectors cleaned up New battery Replaced alternator I am thinking a defective ECM I did see some corrosion on the bolts the bolt the ECM together the car sat for some time

|UPDATED|11/25/2013 8:13:08 PM (AZT)|/UPDATED|


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11/25/13 11:53pm - Reply: 'Re: Check engine light will not go off or flash'
Adams' Apple Lifetime Member
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Duncanville, TX - USA

Vette(s):
#1-1974 L-48 4spd Cp Med Red Metallic/Black deluxe int w/AC/tilt/tele./p/w-p/b/ Am-Fm/map light National/Regional/Chapter NCRS "Top Flight" #2-1985 Bright Red/Carmine Cp.L-98/auto Member: NCRS, NCRS Texas, Corvette Legends of Texas

Joined: 11/8/2003
Posts: 19449
The fuse that operates the "Check Eng" light powers a lot of stuff(Gauges fuse).
The ground for the light comes directly from the ECM. You may have a short to ground in the brown/white wire going to the light, or the ECM may be bad, as you suspect. If it were me, I would remove the ECM, and take the cover(s) off, and have a look-see inside first.
It's possible the oxygen sensor(s) are open/shorted out, too. The check engine light is really to tell you if the ECM has gone into "closed loop" or not. It will not go into closed loop until it sees a valid, switching signal from the O2 sensors. So...you could have one of several issues that would cause the problem. 
Does the car run ok?



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Joel Adams
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11/26/13 7:15am - Reply: 'Re: Check engine light will not go off or flash'
stutrac
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Bethany, CT - USA

Vette(s):
1981

Joined: 11/14/2013
Posts: 32
car runs good,i even tried to disconnect the Negitive battery terminal to clear code's and that did not work light still on.

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1981 Vette
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11/26/13 8:20am - Reply: 'Re: Check engine light will not go off or flash'
Adams' Apple Lifetime Member
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Duncanville, TX - USA

Vette(s):
#1-1974 L-48 4spd Cp Med Red Metallic/Black deluxe int w/AC/tilt/tele./p/w-p/b/ Am-Fm/map light National/Regional/Chapter NCRS "Top Flight" #2-1985 Bright Red/Carmine Cp.L-98/auto Member: NCRS, NCRS Texas, Corvette Legends of Texas

Joined: 11/8/2003
Posts: 19449
The light staying on is either a "hard" code, or a short in the wiring for the light itself. If jumping the ALDL terminals does not cause the light to flash codes, you must have a short, or a problem with the ECM. Ouch

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Joel Adams
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11/26/13 1:22pm - Reply: 'Re: Check engine light will not go off or flash'
dskopp
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Oak Creek, WI - USA

Vette(s):
1981 Great White Shark. Red Interior, 350/190hp. PS, PB (SS), A/C CC, T-Tops, Going to remain as Stock as possible. Served three years in Active Duty Army, then Retired Air Force after 34 years! Badger State Vetts Car Club. 175,000 Original miles!!

Joined: 5/21/2008
Posts: 1956
I had that problem awhile back with my 81.  I replaced the PROM and everything worked just fine!!!

Dan da Man (^^^)



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11/26/13 3:38pm - Reply: 'Re: Check engine light will not go off or flash'
stutrac
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Bethany, CT - USA

Vette(s):
1981

Joined: 11/14/2013
Posts: 32
Where do I get the prom? Cost?

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1981 Vette
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11/29/13 1:37pm - Reply: 'Re: Check engine light will not go off or flash'
dskopp
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Oak Creek, WI - USA

Vette(s):
1981 Great White Shark. Red Interior, 350/190hp. PS, PB (SS), A/C CC, T-Tops, Going to remain as Stock as possible. Served three years in Active Duty Army, then Retired Air Force after 34 years! Badger State Vetts Car Club. 175,000 Original miles!!

Joined: 5/21/2008
Posts: 1956
stutrac said: Where do I get the prom? Cost?


In will check out the prices and then let you know.  If push comes to shove, I have and ECM and PROM that I keep as an "extra" for my car!!

Dan


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12/2/13 10:27pm - Reply: 'Re: Check engine light will not go off or flash'
stutrac
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Bethany, CT - USA

Vette(s):
1981

Joined: 11/14/2013
Posts: 32
i borrowed a ECM from a local person and i still have the check engine light on, the clicking has gone and sounds really good so i solved 1 issue now if i could get the light off or i may just pull the bulb and be done 

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1981 Vette
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12/3/13 1:21pm - Reply: 'Re: Check engine light will not go off or flash'
Adams' Apple Lifetime Member
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Duncanville, TX - USA

Vette(s):
#1-1974 L-48 4spd Cp Med Red Metallic/Black deluxe int w/AC/tilt/tele./p/w-p/b/ Am-Fm/map light National/Regional/Chapter NCRS "Top Flight" #2-1985 Bright Red/Carmine Cp.L-98/auto Member: NCRS, NCRS Texas, Corvette Legends of Texas

Joined: 11/8/2003
Posts: 19449
Have you tried to pull any codes with the other ECM?

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Joel Adams
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12/3/13 1:27pm - Reply: 'Re: Check engine light will not go off or flash'
rraider1
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Woodland, WA - USA

Vette(s):
1977 T-Top,350,Auto Black Ruby Pearl,Steeroids R&P conversion

Joined: 10/14/2003
Posts: 1152
as mentioned above have you disconnected the ECM to see if the light stays on with ECM disconnected. Which would indicate that the brn/wht wire would be grounded somewhere.
Zip has parts
 
 
Which pins are you jumping for ECM diagnostics A-grnd B- Diagnostic.  


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Bob R
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12/3/13 8:30pm - Reply: 'Re: Check engine light will not go off or flash'
stutrac
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Bethany, CT - USA

Vette(s):
1981

Joined: 11/14/2013
Posts: 32
yes i tried to pull codes and no light flashing i used the last 2 pins on the right side

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12/3/13 11:35pm - Reply: 'Re: Check engine light will not go off or flash'
Adams' Apple Lifetime Member
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Duncanville, TX - USA

Vette(s):
#1-1974 L-48 4spd Cp Med Red Metallic/Black deluxe int w/AC/tilt/tele./p/w-p/b/ Am-Fm/map light National/Regional/Chapter NCRS "Top Flight" #2-1985 Bright Red/Carmine Cp.L-98/auto Member: NCRS, NCRS Texas, Corvette Legends of Texas

Joined: 11/8/2003
Posts: 19449
If jumpering the A & B pins does NOT cause the light to flash codes, or at least a code 12(meaning no codes stored) with two different ECMs, there has to be a problem in the circuit for the light itself. Ouch



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Joel Adams
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             NCRS

"Money can't buy happiness -- but somehow it's more comforting to cry in a CORVETTE than in a Kia"
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12/4/13 12:20am - Reply: 'Re: Check engine light will not go off or flash'
rraider1
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Woodland, WA - USA

Vette(s):
1977 T-Top,350,Auto Black Ruby Pearl,Steeroids R&P conversion

Joined: 10/14/2003
Posts: 1152

To clarify the question

With the ECM completely disconnected Does the check engine light remain On?

If the answer is yes the problem would be an issue in the BRN/WHT wire from the ECM to the check engine light assembly

If no and you believe the ECM to be good. you would need to look at the wiring to ECM

 




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Bob R
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12/4/13 11:30pm - Reply: 'Re: Check engine light will not go off or flash'
stutrac
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Bethany, CT - USA

Vette(s):
1981

Joined: 11/14/2013
Posts: 32
mine is a 5

 (modified large image to link-aapple)




|UPDATED|12/4/2013 8:30:14 PM (AZT)|/UPDATED|


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1981 Vette
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12/5/13 8:20am - Reply: 'Re: Check engine light will not go off or flash'
Adams' Apple Lifetime Member
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Duncanville, TX - USA

Vette(s):
#1-1974 L-48 4spd Cp Med Red Metallic/Black deluxe int w/AC/tilt/tele./p/w-p/b/ Am-Fm/map light National/Regional/Chapter NCRS "Top Flight" #2-1985 Bright Red/Carmine Cp.L-98/auto Member: NCRS, NCRS Texas, Corvette Legends of Texas

Joined: 11/8/2003
Posts: 19449
Dangit....that's right.
In that case, you need this diagram....


When you jump the A & B terminals, and turn the key on, you should be able to hear the mixture control solenoid in the carb buzz/click. If it does, it means the ECM is awake, and the Check Eng. light should flash a code 12....one flash, a pause, and two quick flashes. It will do this three times, and then flash any other codes it has stored. Code 12 is just a nothing code..it only means the ECM is in diagnostic mode. If that's the only thing it flashes, it means there are no codes stored.
Then again...if the dadburn light stays ON ...there has to be an issue with the wiring....Cry

CORRECTION! The 5 pin ALDL connector needs the D & E terminals jumped....my bad. Thanks Bob! Embarrassed


|UPDATED|12/5/2013 5:20:14 AM (AZT)|/UPDATED|


____________________________________
Joel Adams
C3VR Lifetime Member #56    
My Link


(click for Texas-sized view!)
             NCRS

"Money can't buy happiness -- but somehow it's more comforting to cry in a CORVETTE than in a Kia"
 Reply Reply  Quote Reply w/Quote
12/5/13 9:43am - Reply: 'Re: Check engine light will not go off or flash'
rraider1
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Woodland, WA - USA

Vette(s):
1977 T-Top,350,Auto Black Ruby Pearl,Steeroids R&P conversion

Joined: 10/14/2003
Posts: 1152

I don't want to confuse things but this GM ECM replacement paper says for 81 jumper D E

http://www.C3VR.com/member_pages/4201_4300/4221/ECM-test0001.jpg 

http://www.C3VR.com/member_pages/4201_4300/4221/ECM-test0002.jpg 

http://www.C3VR.com/member_pages/4201_4300/4221/ECM-test0003.jpg 

http://www.C3VR.com/member_pages/4201_4300/4221/ECM-test0004.jpg 


I hope I made the larger for those of us with older eyes






|UPDATED|12/5/2013 6:43:22 AM (AZT)|/UPDATED|


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Bob R
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12/5/13 8:20am - Reply: 'Re: Check engine light will not go off or flash'
Adams' Apple Lifetime Member
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Duncanville, TX - USA

Vette(s):
#1-1974 L-48 4spd Cp Med Red Metallic/Black deluxe int w/AC/tilt/tele./p/w-p/b/ Am-Fm/map light National/Regional/Chapter NCRS "Top Flight" #2-1985 Bright Red/Carmine Cp.L-98/auto Member: NCRS, NCRS Texas, Corvette Legends of Texas

Joined: 11/8/2003
Posts: 19449
 Embarrassed Thumbs Up

____________________________________
Joel Adams
C3VR Lifetime Member #56    
My Link


(click for Texas-sized view!)
             NCRS

"Money can't buy happiness -- but somehow it's more comforting to cry in a CORVETTE than in a Kia"
 Reply Reply  Quote Reply w/Quote
12/5/13 7:46pm - Reply: 'Re: Check engine light will not go off or flash'
stutrac
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Bethany, CT - USA

Vette(s):
1981

Joined: 11/14/2013
Posts: 32
so am i to assume i jump the 2 on the left NOT the right to get the codes?

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1981 Vette
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12/5/13 11:19pm - Reply: 'Re: Check engine light will not go off or flash'
Adams' Apple Lifetime Member
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Duncanville, TX - USA

Vette(s):
#1-1974 L-48 4spd Cp Med Red Metallic/Black deluxe int w/AC/tilt/tele./p/w-p/b/ Am-Fm/map light National/Regional/Chapter NCRS "Top Flight" #2-1985 Bright Red/Carmine Cp.L-98/auto Member: NCRS, NCRS Texas, Corvette Legends of Texas

Joined: 11/8/2003
Posts: 19449
 

Here's what you need to jump... The black/white wire, and the White/black wire....Thumbs Up

 

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Joel Adams
C3VR Lifetime Member #56    
My Link


(click for Texas-sized view!)
             NCRS

"Money can't buy happiness -- but somehow it's more comforting to cry in a CORVETTE than in a Kia"
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12/6/13 11:35pm - Reply: 'Re: Check engine light will not go off or flash'
stutrac
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Bethany, CT - USA

Vette(s):
1981

Joined: 11/14/2013
Posts: 32
Thank you for the help everyone i got a code 15 coolant temp sensor, i see a few sensors on the block? location.

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1981 Vette
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