tony58

Is it possible for a "92" LT1 to always start,always run flawlessly,get great gas mileage and have a bad EMC?The SES comes on every time I drive the car after reaching 180-190 temp.Code 26-Quad driver modual.I've contacted two local shops,both say it needs a new computer.
If it needs a new computer, I understand they are hard to come by? Any sources out there where one can be bought?
A large Chevy/Buick/GMC wont even work on anything older than a 2000.They no longer have the diagnostic tools to work on these.So anybody in the Nashville,Tennessee area that knows of a older Corvette friendly?
I'm trying to get the car fixed before Spring,so I can sell it.I'm sure Id take a beating trying to sell a car with a SES light on...

billschroeder5842

https://www.corvetteforum.com/forums...code-26-a.html

Here is a link from a CF discussion from a couple of years ago. Maybe a hidden gem for you

tony58

That is some good information.That seems to be close to the same problem I'm having.Difference is my car runs great,his was running crapy.The guy never stated what was the final fix was.Thanks again...

cardo0

That's part # 88999183 for 1992 corvette and 1993 V8 camaro's/firebirds. Rock Auto wants $212 for a reman ECM # 88999183. I found LT1 PCM's for $20 on Craigslist partouts. Try your local boneyard first.

Finding used bargain parts is most of the fun owning a Chevy.

Happy hunting.

MatthewMiller

Here's some more useful info. What this is saying is that the actual "driver module" is a current driver to drive some different components that require real current, rather than the milliamps that the ECM itself uses for its signals. Without this buffer, the little ECM signals would not successfully power these components. If the driver itself is bad, then I guess you're in for a new ECM. There are lots of places to get one, as cardo0 noted.

BUT...if one of those components driven by that module is bad instead, and maybe shorting the circuit, then the new ECM will be a waste of money and you won't solve your SES. That Saturn page I linked lists eight components that could cause this. I don't know if it will be the same eight in your C4, but I bet they are the same or close to the same. My bet is on one of those (you can obviously rule out the SES light being burned out!). But the point is, if something like your "Hot" light is burned out and causing the code, your car will still run great. The fact that it runs just fine makes me think it's not the module itself, but one of the devices that the module controls.

JimLentz

I would put a scan tool on it while driving and make sure the ECM sees the correct engine temps when the problem occurs. These ECMs from the 92 and 93 Corvettes often have a cold solder problem that can cause all kinds of codes/issues. I sent mine off to a place in southern Illinois (SIA Electronics) where they fixed my ECM. It could be that one of the solenoids/relays doesn't operate until a certain temperature and when the ECM tries to operate it there is a short circuit that is detected and thrown as the code 26 you are seeing.

charliet615

Tony58, if you are in the Nashville area, there is one shop I would trust to work on the Corvette. It's the Car Care Center in Pegram, Tn just to the west of Bellevue. Contact Paul Jr @ 615-646-4685. I would let him work on my 93 any time. Charlie

tony58

Thanks Charlie,I just called him,sounds like a very knowledgeable mechanic.He is the only one that said not to change out the computer before any testing.Wanting to sell the car,so got to do something.
I'm also trying to get a hold of Gordon Killebrew to see if he wants to fool with it?(He wrote and proof read our service manuals).I know him from cars shows and cruise in I attend.

bjankuski

Code 26 does not mean computer failure, it is a failure of the evap circuit, it could be bad wiring or the solenoid. Follow the diagnostic chart in the service manual or find a shop that will do the same.

mixalive

That code will set on a 92 if the computer does not "see" the evap solenoid. Maybe disconnected, lost its ground or hot wire is broken. Probe the two wires of the evap solenoid with the solenoid connected with a DC volt meter. You should see a varying voltage up to 12 volts as you rev the engine past idle. The evap solenoid is on the passenger side of the intake manifold, connected with a hose to the throttle body, under the black plastic "Corvette" covers.

tony58

I missed the Saturn page the first time.Found it the 2nd time.Thanks

tony58

Thanks for all the replys. Wow, there are so many things that code 26 involves.Also found this old thread on Google.Might help someone as well as myself?
https://www.corvetteforum.com/forums...river-4-a.html

MatthewMiller

I hope it helps. And FWIW, one of the eight components in that article that are driven by the Saturn driver modules is the evap purge solenoid, as mentioned by mixalive. If the 92 C4 has anything in common, then that all fits together. That evap solenoid is probably a very good place to start checking.

But the bigger message is this: the factory service manual (FSM) will detail this code and provide a diagnostic flow chart to address it. You would also have a schematic to see everything that driver module powers. So if you have any inclination to diagnose and fix this yourself, it is worth laying your hands on the FSM.

tony58

This might shed some light? I've got two C4's.On the 92 when I remove the gas cap even in cold weather, its like you turn on a propane tank.The 96 has little to no spewing out air.