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1982 carbed LG4 can’t read codes

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Old Apr 25, 2020 | 10:26 AM
  #1  
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Car: 1982 Firebird
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1982 carbed LG4 can’t read codes

I insert the paper clip and nothing happens, the light came on after my mods, also most vacuum stuff was plugged just to get me home, I will hook up other stuff if needed
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Old Apr 25, 2020 | 11:18 AM
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Re: 1982 carbed LG4 can’t read codes

I insert the paper clip and nothing happens
Probably the wrong 2 holes then. Re-check where you're plugging it into. Should be pins A & B; it's 2 pins next to each other at one corner of the connector, can't recall which corner it is.

Last edited by sofakingdom; Apr 25, 2020 at 11:21 AM.
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Old Apr 25, 2020 | 11:47 AM
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Re: 1982 carbed LG4 can’t read codes

First off, it's NOT a paper clip. It's a GM Electronic Engine Control System Diagnostic Link Access Tool. It might resemble a paper clip, but it costs a lot more.

Key on, engine off, insert your paper clip, err, Diagnostic Tool in the A & B sockets.



If it doesn't produce results, check the ECM fuse.
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Old Apr 25, 2020 | 12:38 PM
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Car: 1982 Firebird
Engine: 5.0 LG4
Transmission: 200C
Axle/Gears: 2.73 open diff
Re: 1982 carbed LG4 can’t read codes

Originally Posted by Vader
First off, it's NOT a paper clip. It's a GM Electronic Engine Control System Diagnostic Link Access Tool. It might resemble a paper clip, but it costs a lot more.

Key on, engine off, insert your paper clip, err, Diagnostic Tool in the A & B sockets.



If it doesn't produce results, check the ECM fuse.
EDIT: ECM fuse is good not broken or anything I pulled it out. Still can’t check the codes

Last edited by 82Firebird5.0; Apr 25, 2020 at 12:50 PM.
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Old Apr 25, 2020 | 01:41 PM
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Re: 1982 carbed LG4 can’t read codes

Originally Posted by 82Firebird5.0
....It comes off the red battery cable
Originally Posted by sofakingdom
ECM

Other half of it should be somewhere nearby

Might have something to do with your Check Engine light
Originally Posted by 82Firebird5.0
Ok guys I’ve got a mild cam, edelbrock air cleaner, hooker headers and y pipe, advanced cam timing etc
so I extended the factory wiring harness to get the 02 sensor to fit my headers so it’s not an 02 problem. All the vacuum lines not in use are capped off. Any idea what could be causing the light? Which emissions thing should I plug back in to get it to turn off
Don't take this as as scolding , because it isn't .....

You now have at least three threads that I know of in three different areas of the forum all trying to solve the same problem . The problem with posting multiple threads like this is that people who may want to help you might not have noticed the other threads and will be missing crucial bits of the information needed to help you in reaching a proper diagnosis of what's not right with your car . Keeping it all in one thread will give the respondents all the info in one place to be able to formulate the best possible answers .

Now , like Sofa said , I also believe the connection you hold belongs to the fusible link shown powering your ECM in this 1982 CCC schematic I shamelessly pilfered from ATG . Your car's check engine light is driven by a check engine light module that will turn the light on even in the absence of the ECM receiving the 12 volts it needs to run , for that matter you could unplug the ECM entirely and the CEL will still be on , with no signal from the ECM being there to turn it off *.

* Later model cars , like my 1989 for instance , had the CEL module built into the ECM instead of a separate stand alone unit , so this only applies to early cars like your 1982 .


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Old Apr 25, 2020 | 09:26 PM
  #6  
82Firebird5.0's Avatar
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Car: 1982 Firebird
Engine: 5.0 LG4
Transmission: 200C
Axle/Gears: 2.73 open diff
Re: 1982 carbed LG4 can’t read codes

Originally Posted by OrangeBird
Don't take this as as scolding , because it isn't .....

You now have at least three threads that I know of in three different areas of the forum all trying to solve the same problem . The problem with posting multiple threads like this is that people who may want to help you might not have noticed the other threads and will be missing crucial bits of the information needed to help you in reaching a proper diagnosis of what's not right with your car . Keeping it all in one thread will give the respondents all the info in one place to be able to formulate the best possible answers .

Now , like Sofa said , I also believe the connection you hold belongs to the fusible link shown powering your ECM in this 1982 CCC schematic I shamelessly pilfered from ATG . Your car's check engine light is driven by a check engine light module that will turn the light on even in the absence of the ECM receiving the 12 volts it needs to run , for that matter you could unplug the ECM entirely and the CEL will still be on , with no signal from the ECM being there to turn it off *.

* Later model cars , like my 1989 for instance , had the CEL module built into the ECM instead of a separate stand alone unit , so this only applies to early cars like your 1982 .

ok I found the wire and plugged it in, car runs much better now. I am worried though I started the car twice and it quit both times because my dumb self had left the paper clip in the ports. Did I hurt anything it kinda ruined my drive when I was worrying about it. Once I pulled it out it started fine
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Old Apr 26, 2020 | 07:30 AM
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Re: 1982 carbed LG4 can’t read codes

Originally Posted by 82Firebird5.0
ok I found the wire and plugged it in, car runs much better now. I am worried though I started the car twice and it quit both times because my dumb self had left the paper clip in the ports. Did I hurt anything it kinda ruined my drive when I was worrying about it. Once I pulled it out it started fine
Hi 82Firebird5.0 , No , you didn't ruin anything running it in diagnostic mode , the reason it ran like crap with the paperclip in is that the ECM behaves very differently in diagnostic VS regular run mode .

As long as it went back to running good with the paperclip removed , your fine ....
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Old Apr 26, 2020 | 09:03 AM
  #8  
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Car: 1982 Firebird
Engine: 5.0 LG4
Transmission: 200C
Axle/Gears: 2.73 open diff
Re: 1982 carbed LG4 can’t read codes

Originally Posted by OrangeBird
Hi 82Firebird5.0 , No , you didn't ruin anything running it in diagnostic mode , the reason it ran like crap with the paperclip in is that the ECM behaves very differently in diagnostic VS regular run mode .

As long as it went back to running good with the paperclip removed , your fine ....
sweet! It starts and runs a lot better, it’s got old gas so I’m burning it off and I’ll get some fresh to see how it runs. It’s about 60 degrees where I live, and the choke takes about 2 minutes of high idle at 1500 rpm to kick down, the choke closes then opens all the way, after it’s completely open it still is at fast idle even if I sharply punch the gas. Eventually I can get it to kick down
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