Finchinater

Didn't help much to get the definition. I don't know what exactly to check.

Evaporative Emission (EVAP) canister purge solenoid valve circuit. This is the definition off of shoebox's site. Do I check the canister or the circuit.

Where do I find these on my car?

BTW, 93Z , catback, CAI, 115k miles. That's about it

busta9876

there are two solenoids on the intake, one on each side of the intake. The one on the drivers side is the EGR solenoid, the one on the passanger side is the EVAP purge solenoid. It's a two wire electrical connector, one wire should have +12v with the key on, the computer commands the solenoid by providing the ground to the solenoid.

also check vacuum lines form intake to solenoid, and solenoid to canister.

the computer does a few checks on the EVAP, one checks the circuit, the other watches the MAP when EVAP purge is commanded, and checks to make sure there was a change in pressure the split second EVAP purge was commanded. if it does not see this change, it will set a code.

chances are its electrical, bad solenoid, or fuse blown. if one wire does not have 12v with the key on, probably a blown fuse.


good luck

Injuneer

You have a 93, and the code list is different than the 94/95 cars. Shoebox's list has both sets of codes, where they are different. In the 93...

DTC 26 = Quad-Driver Module (QDM) #1 circuit
applies to:
- AIR pump relay circuit
- EGR solenoid
- EVAP solenoid

Could be a problem with any one of those three items, or the Quad Driver itself.

To my knowledge, the check is purely for electrical continuity.

busta9876

i remember that know in the 93...my first lt1 swap was a 93..i had the Quad Driver code, ended up being a damaged pin in the EGR solenoid plug, someone had jammed a test lead in there and it had an intermitant connection.

with the codes i remember the fans kick on too.

Finchinater

I appreciate the responses guys. So basically, break out the volt meter, check electrical connections, check for blown fuses, check vacuum lines to intake.

Injuneer, I honestly don't know what the QDM is and don't know what to look for and what to check. I could really use your wisdom. My car has been runnin' rough for about a month, PS manifold is glowing at night, 2k studder, smell of exaust inside, bad gas mileage and low power when up to temp. I'm sure it could be one little thing that escalated into my current problems.

Anyway, pix and or detailed instructions would be helpful from anyone. I can knock it out tommorrow, but the weather in ohio is starting to be not so friendly.

Thanks again

busta9876

1993 LT1

Grey PCM connector

Pin 1 evap solenoid control green wire
Pin 2 egr solenoid control gray wire
Pin 8 air pump relay control dark gray wire

first thing i'd check for power at all three of the above, i think they all use the same fuse..so if 12v at one, all should have power, unless wire is broken somewhere.

if power is good, i'd check the ohms on the three above, also check the pins for damage when you disconnect them. I don't know what the ohm value would be on the solenoids, 5 to 15 ohms i would imagine.

are there any other codes in the ecm? glowing manifold doesnt sound good.

good luck! let me know if you need to know anything else.

the code 26 will be electrical, not vacuum lines or somthing like that.