I do see the white with a black wire witch some sort of green conector just hanging there, I have to get my light working before I can read the code as far as only 3,221 ca emissions Corvettes sold "Gulp" I wish I had a smog guy to help me through this initial smog,, DMV wont even give me my title till I get this done. I feel pretty defeated right now.

 

Ok so if the computer is dead will I have no light at all or full time light or?

 

I didn't know that. I assumed that they used the same computers as the 81's. I stagnd corrected.

 

Rusty, you're going to need a lot of patience with this one. So far you are on the right track with identifying the CEL diagnostic connector. It is green and your absolutley right on with the location (just hanging there next to the battery). Your car doesn't have the convenience of the plug-in-type connector found with OBDII systems. Get the bulb replaced. Turn the ignition switch to "ON" without cranking the engine over. Then ground that green connector (I think your supposed to disconnect one of the battery terminals but not sure). Once grounded you should see the CEL flash. Let us know what you get.

 

If the bulb and computer are good, you should get some kind of light. I believe you should get a code 12 indicating that the system is working. However, with all of the emmission parts that your are missing, that could be a cause for no light at all. If you have no light after grounding and you are sure the bulb works, I would start with replacing/finding all the emmission related components to make your car correct. Start with what parts you can afford first, and take your time with it unless this is your DD and need to get it registered ASAP.

Welcome to the club and enjoy!

 

The system is designed so that when the key is turned to the ON (or run) position, but the engine is NOT running, the check engine light will come on as a test of the bulb and system (ECM). If the computor is functioning properly, and the bulb is good, the engine light should be lit when the ignition is turned on, but the engine hasn't actually been started.

When the ignition is turned on and the engine is started and running, the check engine light should go out. If it doesn't go out, this indicates a problem in the system, and a trouble code should be stored in the ECM.

If you have an intermittant problem, the light will come on for about 10 seconds, and then go out. Even though the light has gone out, the ECM will still store the code(s) of intermittant problems. The system will save intermittant codes for 50 engine starts, or until the battery is disconnected.

Since the engine light will remain lit as long as there is a problem with the system, it's pretty common for people to remove the check engine light's bulb, instead of correcting the problem. This is what probably happened with your car. When a previous owner had a problem with the system, or removed part of the emission equipment, the light was triggered and the bulb was then removed.

I'm pretty sure that the battery needs to remain connected to perform the test. Disconnecting the battery, will clear any stored codes from the ECM.

 

if you think that you need help finding parts or just need a hand ,i would find your local corvette club .they will have people who know what needs to be done to pass all those smog tests.good luck

 

And, [I believe] if you turn the ignition to ON [engine not running] and the CEL bulb does NOT light, it would be an idication that the ECM was not working or some problem with the wiring...most likely the ECM would be: defective, getting no 12v power, or getting no ground.

You mentioned a problem with grounds on your car. If you have a problem with the main ground wire from the neg terminal on the battery and going to the frame, everything electrical will be compromised. I suggest that you remove the neg. cable from the battery, check the wire/connector for solid joint (no corrosion, no broken strands, etc). Also get underneath the battery compartment and remove the other end of that line from the frame mounting. Clean it all up, use sandpaper to scuff/clean the frame where that lug is mounted, clean the bolt & washer. If you have an ohmmeter, connect the leads to both ends of that removed ground wire; set the meter to read resistance on the lowest scale possible. If the meter reads more than .2-.3 ohms, the cable may be bad. Once you have it hooked up, shake/wiggle each end of the wire to see if the meter changes reading; if so, it may indicate an internal fault with the wire. If you have any concerns about the condition of that wire, replace it. You can have one made at a local (full service) parts store, or you can make your own with a short piece of 2 AWG wire with a copper lug on one end and a new bolt-on battery terminal (cheap at auto parts store) on the other.

Your problem could be as simple as a bad ground wire. That may fix some of your problems and get the ECM working again. That would allow you to get any trouble codes [after you operate the car a few times] if it throws any. The diverter valve is a different issue. You may want to go to a GM/Chevy dealer and work with the Parts counter guy to look up that diverter valve for your Corvette...then check to see if any other GM cars (for that model year and later) used the same valve. With that info, you can call some auto parts salvage places and see if they have any of those vehicles with a diverter valve that is intact.

I wish you luck with solving your problem. But, your first order of business is to get that ECM working...or replaced...and get the trouble codes to determine where to begin fixing things. Good luck.

 

Ok thank you for all the help everyone. My brother in law is a police officer here in nor cal, and before I bought the car i asked him to run the VIN to see what he would find. Well car wasn't stolen or anything be he did find that it was listed as totaled in the early 90's As far as I can tell somebody bought it in Nevada and repaired it pretty much complete, as I have a repaired title from Nevada. I am guessing thats why it has a 1996 GM Good wrench 350 crate motor in it. I am surprised that some one in Nevada even put all these emission control stuff back on it at all. The ECM has yellow paint marker on it sayin "80 Vette" like from a junk yard. Everything seems to be here but not working at this time.

 

One more interesting thing, I suppose I would call it, I found, is my worthless Chilton book at least did tell me what wire from the computer should be grounded. So I did a simple continuity test with me ohm meter between that wire and the ground terminal of the battery that is right there, with the plug unplugged from the computer I did not get a signal, so I got excited for a second thinking I may have found a problem, but when I plug the connector back into the computer, only then I have a continuity signal to ground??? so that one is a bit confusing. As far as I can tell from this book the wire comes out of the computer and grounds (somewhere) having a ground signal only after the plug is connected seems like a short in the computer. But I have no idea. I also with the computer all connected rigged up a jumper wire with a small 1.5 amp fuse in it (I diddint wanna make matters worse by possibly frying stuff) and i jumped this terminal on the computer to ground and did not notice any change. So until I can get the light in the dash, hopefully later today, I will not know more. Rusty

 

Well this is not my DD and I suppose I am not in a big rush to get it reg, but I am running out of time on this red window sticker DMV gave me. I am not sure if I can get some sort of extension. I obviously have to drive it at some point to get to the smog shop. Ill likley get pinched by tha police and enter the next level of this misery.... I just finished fixin up a 57 Chevy Pickup that I did a 4x4 swap on. I swore I would never mess with non pre smog vehicles again but here I am

 

Rusty,

I know I am late to the party, but are you stil looking for the valve? I have an '81 that I took all the smog stuff off and saved. I will check the smog pump to see if I have the valve, I am at work now but will check tonight.

 

YES! that would be awesome thank you! Rusty

 

Get the CEL bulb in the socket and check its intergrity out first. Don't go 'foolin' with the computer until you can watch the CEL to see what it's doing. If it works, then get any codes. If it works and 'no codes', fire the engine and let it warm up; then (while stopped) run it through the gears on the tranny and shut it down. Check for trouble codes again. If none, the system should be working. If you have codes thrown, write the numbers down (they flash in sequence of 2-digit codes until all are displayed). As far as checking out the computer...don't waste your time. Check out the power signal going to the computer and check out the ground wires that run from the computer...but you can't really do anything with the "box" except screw it up by doing something you shouldn't. If you get it diagnosed down to the ECM being the problem, buy a new one.

But, ONE STEP AT A TIME and the CEL bulb is #1. Keep chuggin'....

 

Hey Rusty...does Cali grandfather in older cars for emissions? In Ct. where I live the cut-off date is 25 yrs. for testing. any car 25 or older is exempt to emission testing... Jim...

 

Well they do and the year used to go up every year, but our good friend Arnold Schwarzenegger passed a law to stop if forever at 1975 so any year 75 and newer has to be smogged

 

It seems that the instrument cluster only comes out from behind the dash which means removing the dash am I wrong? next to avoid doing that right now to install a CEL light bulb, I just hooked my test light up to ground and pluged the probe into the connector on the computer that should be the CEL wire. I got nothing key on, then tried with engine started and no light at all. Should this work? or did I just confirm a dead computer Thanks again for all the help Rusty

 

oops

 

You do not need to remove the dash, to change the bulb. The speedo/tach lens is held in by 4 screws, and then screws that hold the speedo/tach assenbly in the dash, can be accessed.

A 1980 assembly manual would be a big help to you, in understanding how the dash is assembled.

I don't know enough about how the 80 diagnostic system functions, to say that this proves anything. I believe the diagnostic terminal's only purpose is to activate a flash code through the check engine light. I'm not sure, but without the check engine bulb being installed, just grounding the terminal may not complete the circuit??

The whole system is designed to work around the check engine light. Not only does it signal fault codes, it's also intended to light to indicate that the system is functioning properly. I think that replacing the bulb needs to be a top priority, if you want to get the system functioning.

If CA is anything like NJ's emission testing, the engine light is the first thing they check. An improperly functioning check engine light is an automatic failure, even if everything else is working correctly.

 

You can get an ecm unit from ecklers, it will be rebuilt. I bought one a few years ago. You might change the oxygen sensor located in the exchaust also.