Reading OBD I codes with a multimeter

[kringold]

Only in order for me not to repeat myself please see the thread here.
hotrodders.com/showthread.php?p=463808#post463808

[Venturi]

Hi kringold welcome to the site.

You can't display the codes with a multimeter that way but it is easy to do it with a paper clip. The following page shows how and also list the code definitions.
www.troublecodes.net/GM

I plan on adding code display procedures for most OBDI vehicles on site but I haven't had a chance yet.

[DanD]

Hey kringold great to see that you made it over.
If this is the same Chevy we’re talking about why are you worried about codes? With all the modifications and changes made, (that we discussed over at Kurt’s site) this computer won’t have control of anything anyway.
If it’s because the service engine soon light is on, I suggest pulling the light bulb.
Dan.

[kringold]

Yea it's the same but the carb is a feedback carb and doesn't the puter control it? I'm finishing up the wiring (still have a couple unknown ones) and when I do fire it up, I want to check to make sure what I do have hooked up is right and not grounded/shorting out.

[DanD]

Yea you’re right it’s a feedback carb and the system was originally designed to have the fuel mixture automatically adjusted via a mixture control solenoid receiving commands from the computer.
The computer makes these commands after it analyzes information from the inputs, like the coolant, air temperature, MAP, TPS, vehicle speed and O2 sensors ect.
If the computer does not have all of these inputs for whatever reason, disconnected, poor connections or bad sensor the computer will go into a default mode. In other words the computer will try and set everything to a preset known value that will allow the engine to run and leave it there. The computer will also go into default if it makes a command and it doesn’t see the result it expects.
That’s why I asked why you where worried about codes, because of all the different things that we talked about on that other board. (Can’t remember it all) Other than at that time you said that you were not concerned with emissions and just wanted what you needed to run the thing and give you oil and temperature warning lights.
If you changed your mind and want it all to work as intended, I /we will try and help sort it out but we could be in for a long frustrating time doing so.
I still say, fire the engine up with whatever that isn’t connected and see how it runs, you won’t hurt anything if it’s unhooked.
One other thing is, if by chance there is something shorted to ground, as soon as you turn the key on to check for codes you will have fried whatever that might be anyway. So have a look around for anything obvious that might let the smoke out of a sensor or the computer, if you don’t see anything hit the key and see what happens.
Dan.