car is throwing dtc:26 . What do i need to replace to fix?

 

DTC 26 is Quad-Driver Module (QDM) #1 Circuit...I am looking inot that for you....

James

 

Check the evap purge solenoid for a shorted coil. It's on the right side of the manifold plenum and it should be 21.8 ohms approx.

 

ECM detected the wrong potential voltage at the #1 quad-driver module circuit for 20 seconds. To reset, remove power from ECM for at least 30 secs!!

http://www.troublecodes.net/GM/

That might help ya out man!!

James

 

"Check the evap purge solenoid for a shorted coil. It's on the right side of the manifold plenum and it should be 21.8 ohms approx."

Hey man...that code is for the 94-94 LT1 PCM's.....


Just pull your PCM out for about a minute or to to reset it and if it still does that THEN try the EVAP purge solenoid...but th DTC 26 code is the code for 94-95 LT1's

James

 

That's right it is, but a quad driver is a semiconductor device that drives 4 outputs. The evap solenoid is one of the items that quad driver #1 switches. The others may include the EGR solenoid and Air Pump relay.

 

Youre right!! My bad....I failed to look in the diagrams. I just wanted to find what the code was first and then go from there....good looking out!!

James

 

I haven't seen any drawings that show which driver controls which devices. I just know frome past experiences that the possible cause for #1 driver failure is the the Evap solenoid. If you have a source that lays out exact Driver loads for 93's please point me to them.

 

I actually have the same DTC code on my 93. Do you by any chance have it turn on (SES light) a few mins after you start the car, and not turn off till you shut the car off. then repeats?

 

It will come on after a few minutes. I have access to a snap on scanner at work so i can reset the pcm from there, but the code keep popping back up even with the air pump re connected.

 

Is the fuse in the AIR pump good?

It sure would be nice if someone could confirm or prove wrong the premise that the 93 Quad Driver codes correspond 1:1 with the 94/95 codes. I've been asking that question for several years. Seems logical, but they don't necessarily appear to match.

 

Maybe this will help prove that....

http://www.troublecodes.net/GM/

Or if that doesnt help....just pick up like a Chiltons or a Haynes manual. It shows both years. (well 93 vs. 94-95)

James

 

The list you posted for the 92/93 LT1 ("P"), and Chiltons show DTC 26, 27 and 28 as "Quad Driver" faults. But none of those references confirms what the QD is connected to.

 

Do you have a manual with wiring diagrams? Chiltons has like 2 different ABS circuits on there...but only shows ABS components!
You would have to have a circuit description or know the COMPLETE theory of operation of ABS...mainly just the circuit description!!

Thats all I can say...but I will keep looking...

James

 

What does the ABS have to do with the PCM? Absolutely nothing. I have a Chiltons. I also have a GM manual fo my car. It's a 94 so the wiring is the same as a 93 with a few minor exceptions. Quad drivers have nothing to do with ABS. The systems are seperate, completely. Chiltons, Haynes(the worst), or any other don't show specific quad driver loads. All they show is pinouts(if that) from the PCM and not internal parts. Like I mentioned before and Injuneer also mentioned, the Air pump relay, EGR, and Evap can be suspect of causing this fault. I know for sure that the evap is on quad driver #1.