briand354

Quad Driver Module 1 Code 26

This is the code that I am getting.
Do I Need a ECU? Thats basically what everyone i have searched on the internet is telling me.
Please let me know.

If you have one I am interested if that will fix the problem.
It runs rough, and is f*ked until I replace the ECU I think.
but let me know, these things are hard to come by.

anyone?
-Brian

Muffin

It would help if I knew what year car you have, or am I missing something here?

briand354

Sorry. I must have spaced. It's a 1992 lt1

blackbear bob

Code 26 QDM 1 means the ECM has seen a shorted condition in a circuit connected to QDM 1. It is not the fault (usually) of the ECM. You must identify the shorted component in the circuit. Replacing the ECM will most likely result in the same code.
Bob

blackbear bob

Things to look at are AIR solenoid, EGR solenoid and the most comon cause the purge solenoid. One of these is shorted causing the code.

I can link the diagnostics if you'd like
Bob

briand354

I would love the diagnostic for this. Im lost and cant find too much info on how to fix this.

Any help offered would be greatly appreciated.
Thank you in advance.
-Brian

blackbear bob

try this.
Disconnect the above solenoids one at a time and see if the condition clears. Also you can check the resistance of the when they are disconnected. One of the is shorted, or the wiring has a short.
Bob

surfer93

I got mine when my Evap solenoid went belly up.

But it is usually not a short but one of these 3 items -

1) Evap Solenoid - this would be my bet, as they are turned off and on frequently
2) Air Pump relay - real easy to check, start your engine and listen for pump.
3) EGR Solenoid

briand354

Well, Heres my next problem, I cant find any of the things to disconnect.
I went snooping around the engine, and I know where the EGR is, I dont know where the air pump is, let alone how to disconnect it.

Does you have a picture of any of these things or, possibly a map of the whole engine?
can you take a picture of what I should be disconnecting?

Thank you..

briand354

Could you send me a pic of these things?
I cant find them.. I dont have a detailed layout to find where they are.

Thanks.

jaa1992

Don't have a picture, and most of that stuff is off the 92 race car.
Maybe this will help:
look at the drivers side of the intake.
Find the intake manifold bolts to the rear of the looped hose
One of them has a black box with 2 vaccum lines and an electricl connection.
This is the EGR selenoid.

Look at the passenger side of the intake
Find the front intake manifold bolts
one of them has a similar looking black box with 2 vaccum lines and an electrical connection.
This is the EVAP selenoid

The AIR pump is in the area under the driver front head light.
Its kinda noisy, have the hood up, start the car, get out and listen to that area. If you don't hear a high pitch whine then it is in the wiring or relays.

Please get a copy of the Factory Service Manual - it will save you tons of time and frustration.

toptechx6

First page of DTC 26 diagnostic chart showing wiring diagram.



Electric air pump, left front behind headlight, the relay is mounted to the cover



Air bypass solenoid behind AC compressor below ASR servo, has vacuum connection on top, wiring is below (white tab on connector)



EGR solenoid, (blue connector) under left fuel rail cover, lift straight up to remove cover.



Canister purge solenoid (red and blue connector) under right fuel rail cover



Most quad driver circuit one failures I have diagnosed are purge solenoids that fail "open", a quick check is remove the connector then take an ohm reading across the two pins of the solenoid, if it is open (infinite resistance) it is bad.

briand354

Hello ...
First of all I would like to say thank you and I love you guys for helping me with my problem here.
I havent totally figured it out yet.. but Im working toward the resolution.
I measured the resistance of the ohms on both the EGR solonoid as well as the Canister Purge valve solonoid and they are both OL (open loop)
meaning they are both bad. I have the EGR solonoid, and I am awaiting the canister purge solonoid.. So, just for the hell of it, i measured the ohms of the new part.. to make sure im doing it correct and it comes back with a value. So, as soon as I can get the other part.. hopefully this weekend.. I will be out there trying to put these bad boys on.

thank you so far for your help and I will give you an update asap.

-Brian

briand354

Hi.

its been a year.

I am not able to get this car running correctly, and still need help.

I replaced the things mentioned, and still nothing.

Could this be in fact the ecm ?

On the diag sheet it is the last thing there

-Brian

briand354

I replaced the EGR solonoid, and I think the canister purge solenoid

What now ?
ECM ?

toptechx6

Doesn't sound like you did any of the diagnostic tests just threw parts at it so why not guess at the ECM? Its only money.

briand354

I did do the diagnostic, like a year ago now (or longer)

I replaced those parts, and didnt fix the problem.
They were only like $50 for the both of them.

But,
when the mechanic had the scanner connected we got the
'quad driver ' code mentioned above, and once the car was running, he was unable to communicate with it, and everything was N/A.
In his opinion in needs a ecm.

Anyone in RI have an extra ECM, or will lend me one to test ?

Thanks,
-Brian

pcolt94

Could this be a late 93?


Code 26 is different for a 92 compared to a 94. On a 94 the code is the evap canister. And the 92 is the quad driver. I believe the posts relating to the quad driver for the 92 is the correct path.

I had the same code 26 for my 94 but the solution was different. It was the solenoid…easy fix.
You got to use the right book and information to be in the right place.

briand354

Well, as I said before, I replaced the EGR solenoid, and the canister purge solenoid.

I am going to have the mechanic look at this again.
Well used the reference material from above, and with the parts replaced, there was no change in running condition/codes.

Hence the reason, the mechanic said it is the ECM.
I just didnt want to throw $350+ at an ecm (which NO ONE stocks) to find out i am replacing something blindly, and it wont even fix the problem.

$50 isnt that bad for the thing i did replace .. (solenoids), the originals seemed old, and did nothing to fix the codes.
Also, the air pump seemed fine to me at the time.

Any suggestions from here ?
Im thinking about starting all over again, and re-trying the diagnostic.
Maybe i am the fail, but I dont think so, I tend to agree its the ecm.

When i was driving the car, on the highway during the summer, all of a sudden, i have the CELs, and it felt like ****.

My mechanic corfirmed only 1/2 the engine was firing.

-Brian
\

pcolt94

Check the injector fuse for each bank. #21 & 22.


In reviewing the information again I can see how with one error code (26) you could go in 4 basic different directions. Not a real dedicated error code. The ECM probably just has a quad switch in one chip.

But I still recommend the advice offered where you are going to have to isolate all inputs to find if it is the ECM or not.