Check Engine Light

[klgray]

Hello everyone

I just took my 81 vette to get the oil changed, and the antifreeze flushed, and now the check engine light is on steady. Any suggestions?

Kevin

 

[Evolution1980]

Kevin, it sounds potentially specific to the computer in the '81, so I moved the thread into here where the L81 "experts" hang out.

 

[Sensei]

Try disconnecting the battery for 30 seconds first and see if it will just reset. If that does not do it, you will need to check for trouble codes. You can do this with a paper clip by shorting the last two terminals of the connector under the ash tray and the engine light will flash the code #s. I have a computer that does this so I have never actually done it the paper clip way. Perhaps someone who does it this way will chime in. Once you have the code #, I can help you more. God bless, Sensei

 

[SIXFOOTER]

Hwy Sensei;

What kind of computer do you have for checking codes? I am going to need to get one

thanks
Danny

 

[Nut]

Check the L81 registry site to see if the code list is posted. I'm sure it is somewhere. If not, pm (rare81). He sent me the flash/code sheet years ago.

......... nut

 

[Sensei]

My diagnostic computer is a OTC Monitor 2000. They don't make them any more. The new diagnostic computers I found that would read an '81 were very expensive. I was patient and just kept an eye on Ebay until I found one that would work. I picked it up for $25, great deal. God bless, Sensei

 

[SIXFOOTER]

Thanks

 

[Yoda]

It is not a requirement to have the diagnostic hand held to get the codes It's nice, but not necessary..

Chapter 6E in the GM Shop Manual (ST-364-81) provides step by step how too starting on page 6E1-8

I'll do a search and try to find previous discussions here too. We've had some pretty good tech discussion in the past and it may help

Oh, if you don't have a GM Shop Manual and the 1981 Assy. Manual.. I HIGHLY recommend both as they are great sources for diy and great source of information if mechanics need it

Bud

Here is a a link that might help Code Reading The first page or two may not interest you, but it is information and by the 3rd page it should grab your attention

 

[SIXFOOTER]

I actually have 3 manuals, an AIM and a parts manual. The problem is, I like toys, so I am trying to figger out what kind of analyzer to plug in there

Is there some OBDwhatever to be looking for?

 

[Yoda]

I bought a handheld from a guy on Ebay, he said it was for a 1981 Corvette :eyerole

I paid $45.00 for it. Got it with no instructions but it did have a tag on the back with Code Errors and GM 1981 ~ 1997 I got to looking at the Code Error Codes on the back of the handheld and they didn't/don't even come close to matching up with the Codes as described in the Shop Manual :ugh

So I have it in my tool box in the shop, and it looks nice ... my recommendation to anyone looking to buy a handheld is to have the seller provide the Trouble Code Error descriptions and make sure they match with the Shop Manual

Here is the handheld I bought, that is LQQKing Good in my tool box
OTC
Monitor 85
mfr. Owantonna Tool Co.

If anyone can use this, pay shipping + $20 and it's yours, just contact me and I'll get the shipping costs and contact you back I don't even know if it works, never tried it :bash

Bud

 

[klgray]

Code

Try disconnecting the battery for 30 seconds first and see if it will just reset. If that does not do it, you will need to check for trouble codes. You can do this with a paper clip by shorting the last two terminals of the connector under the ash tray and the engine light will flash the code #s. I have a computer that does this so I have never actually done it the paper clip way. Perhaps someone who does it this way will chime in. Once you have the code #, I can help you more. God bless, Sensei

Hi Sensei

It appears the code # is 44. Can you help me out?

Thanks!

Kevin

 

[klgray]

I replaced the O2 sensor tonight, but the problem recurs. I disconnected the battery to reset the OBD, and now the code just gives me the inital code 12.

Any ideas at this point?

Thanks!!!

Kevin

 

[Evolution1980]

now the code just gives me the inital code 12.
Any ideas at this point?

Kevin, I'm assuming that you don't have the owners manual or the assembly manual ("AIM")? That would likely give you the run down of codes.

Don't take my comment to me we don't want to help. Quite the opposite! I just said that as more of an "FYI...it's good to have it" if you are interested in working on your own car. :cool

 

[Yoda]

Here is another Excellent Thread listing the Codes and other information

When I first got Rare in 1997 I had issues with the check engine light coming on it would clear for a bit then start up again. I eventually replace the Computer with a NAPA one (I think it was about $85.00 or something like that) and I've been Code Free since...

Good Luck and keep us in the loop I'm sure others will be able to reference this thread in the future

Bud

 

[Sensei]

Kevin, I assume you mean the check engine light is still coming on but when you check you are only getting the code 12 now? You probably have a weak electrical connection somewhere. This is an easy and cheap fix. Buy this:

http://cgi.ebay.com/Caig-Deoxit-DP5...ryZ88433QQssPageNameZWDVWQQrdZ1QQcmdZViewItem

Disconnect your battery, then put a very small amount on:
1. The connector on the ignition module under the distributor cap (don't remove the module, just unplug and treat)
2. The 4 pin connector coming out of the distributor.
3. All terminal connections on the ECM itself.
4. Any other electrical connections you feel up to treating. (O2 sensor, carb connections, diagnostic port connections, etc. etc....)

This is good stuff and will make your 30+ year old connections like new, but it only takes a small amount, too much is messy and attracts grime. It's like caring for a gun if you are familiar with that. God bless, Sensei

 

[Evolution1980]

Here is another Excellent Thread listing the Codes and other information

Bud, you should talk to Rob and get that post (with the addition of Code 42) into the tech section rather than have it embedded/buried in a thread from years ago. That would certainly be a good reference to have in the tech section / knowledgebase.

 

[klgray]

Final Diagnosis

Kevin, I assume you mean the check engine light is still coming on but when you check you are only getting the code 12 now? You probably have a weak electrical connection somewhere. This is an easy and cheap fix. Buy this:

http://cgi.ebay.com/Caig-Deoxit-DP5...ryZ88433QQssPageNameZWDVWQQrdZ1QQcmdZViewItem

Disconnect your battery, then put a very small amount on:
1. The connector on the ignition module under the distributor cap (don't remove the module, just unplug and treat)
2. The 4 pin connector coming out of the distributor.
3. All terminal connections on the ECM itself.
4. Any other electrical connections you feel up to treating. (O2 sensor, carb connections, diagnostic port connections, etc. etc....)

This is good stuff and will make your 30+ year old connections like new, but it only takes a small amount, too much is messy and attracts grime. It's like caring for a gun if you are familiar with that. God bless, Sensei

Hi Sensei - Thanks for your good advice. I kept having the error even after checking and spraying all of the connections, so I finally gave in and took it to the shop. It turns out that the ECM was bad. The shop said that it was giving out spurious codes.

I'd like to get a OBD sensor for my vette - thing is that the modern ones all start in 1982, with 12 pin connectors. Any advice on where to get one that fits our 81 vettes?

Regards,

Kevin

 

[Sensei]

I found my OTC monitor 2000 on ebay. Just search "1981 diagnostic" on ebay motors parts and accesories. Check every day and be patient. I got mine for $25! There is an OTC monitor 85 on there now but I did not see the adapter for our diagnostic port and they seem to want too much money for it. Again, be patient. BTW, that's the place to get an original GM 1981 Corvette Service Manual too. You need that more than the computer. God bless, Sensei