rollin93

I am getting the abo9ve code on a 93 TA. Can anyone lead me in rthe right direction. What does this module associated with? Where to start trouble shoooting.

Thanks
Brian

aboadnan

See this it might help.

http://web.camaross.com/bb/Forum28/HTML/002883.html

DinoZ

Not to dig up old stuff, but I'm getting this code on a 93 Z28 that we just picked up. I tried the link above, but it says page cannot be found.

Anyone able to hook a brother up, on what exactly this code means, and/or what I have to do to take care of it? TIA!

mike 96 ws6

i don't know the answer but am interested in what it is. i have a freind with a 93 buick 3800 v6 with that code 26 quad driver module. i remember seeing that code back in those days but don't remember what the solution was. anyone???

smoknta

I think that code has to do with the AIR pump or the EGR valve.

will69camaro

Digging up an old thread so i'm not accused of "not searching" I have a 69 camaro with a 94 LT1/T56 swap. I recently started it up and a few codes were thrown. The only one that is concerning me is the "DTC 26: Quad Driver Module1 Fault" The fans kick on immediatly which to me suggests that it is in what is known as "limp home mode." What exactly is the quad driver code? I had the harness modified to remove the air, egr, evap and the PCM is STOCK (no programming yet at all). I called the wiring place and they say my PCM is bad. I called Bryan at PCMforless to get a second opinion on that and he concurs. I spoke with my buddy about it (he's an early GM FI EXPERT) he says he just doesn't think the PCM is bad. While doing testing for me on his TPI car he pulled the plug for the EGR and it threw a "quad driver moduleA fault" is it possible that the computer is still searching for the EGR or another sensor on the same quad driver and isn't finding it and throwing the code? Trying to do a little research so i dont drop 100-150 on a new pcm and have the problem still exist.

Thanks,
William

Injuneer

If you have a 94 PCM, you're using the wrong DTC code list. Hard to believe none of the other people you asked noticed that. They stopped using the "quad driver module" after the 93 models. That's why his TPI responds differently as well. In a 94:

DTC 26 = Evaporative Emission (EVAP) canister purge solenoid valve circuit

When you removed the "evap" system, the PCM no longer sees the correct voltage when it attempts to ground the evap purge solenoid. You would have to put the correct resistor into the wiring harness, in place of the missing solenoid. You will get the same problem for the missing EGR solenoid (DTC 27), and if you didn't wire up the AIR pump relay and insure a good fuse in the circuit (DTC 29). Or, you need to have your PCM programmed to delete the diagnostics.

When you need to look up a code, use Shoebox's list... it shows the differences between the 93 and the later LT1 cars.

http://shbox.com/1/Dtcs.htm

will69camaro

We used a scanmaster and entered the VIN from the 94 camaro and it brought up that code. I'm glad to hear that it doesnt seem like it will be a PCM problem. I had the wiring done and it was supposed to have all that removed (EGR, EVAP, AIR, etc...) There was a guarantee on that so are we sure that it's not a PCM problem? Do you know how big a resistor i need to put in to make the code go away? Will the DTC 26 code make the car run in "safe mode"?

Thanks,
William

Injuneer

You can remove the wiring for the unused components, but then you have to eliminate the diagnostic codes. Or provide some sort of false load.

The diagnostic for the EVAP purge solenoid is looking for near "0" voltage when the PCM supplies the ground to activate the solenoid. The purge solenoid is 35.4 ohms resistance. You could get away with a much larger resistor, to keep the "watts" requirement of the resistor to a minimum. On the skip shift solenoid (12.4 ohms) people are generally able to get away with a 2,000 ohm resistor. The diagnostic for the skip shift solenoid is similar to all the others - looking for near (but not equal to) "0" volts at the PCM when the device is activated.

I doubt the PCM does very much in the way of "protection" on DCT 26. There is no inherent risk of damage to any component of the vehicle if you lose the purge stream. The PCM will turn on the fans for DTC 29 but I don't think it takes any other protective action. Not sure why it even turns the fan on.

Fastbird93

Well, seeing as how you have a 93, the following are directly from my 93 service manual:

DTC 26 Description

DTC 26 Disgnostic Chart

will69camaro

I have a 94 that i'm using and that's what my questions were pertaining too.

William

Injuneer

You lost the "continuity" of the thread. While the person who originally posted this 2-1/2 years ago ago owned a 93, the thread was resurected from the dead recently by "will69camaro", who in fact has a 94 PCM.

will69camaro

LOL i guess i did bring back a thread that was a "little old"....I now have video of my car but waiting for it to be hosted then i'll post it up.

William

Fastbird93

Well.......ahem.....yeah.......

Yes folks, I am a master of the obvious.

That said, there should be an inherent amount of similarity between the 93's and 94's so those charts should help out some, at least to put you guys in the right direction.