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QDM Fault


jonlabree

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Hi, Jon!

QDM = Quad Driver Module = the 4 separate circuits/modules of the ECM. Each module has it's own set of sensors/system to handle. When the 4 don't all return the expected value, the QDM error code is displayed.

Best to spend some quality time with the FSM, and the diags in the car. I once solved a QDM error by replacing the ICM and coils, but would'nt suggest that as the only solution. It could be security, emmissions, crank/cam sensors, or just a bad wire in your harness. I'd need some alone-time with my FSM, and your car, to devine the precise diagnosis.

What other symptoms have you been experiencing, Jon?

Sleeplessness? Irritability? maybe even constipation, or restless third-leg syndrome?

These are all symptoms of a QDM error.

You should call your Reatta-healthcare professional, and get 'yer prescription re-filled today!

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Guest RattyOne

Good Ol' E026 - got the same problem. Seems the drivers provide a ground or lift it when required. Looked up the problem on the website and got all the way to "look for loose grounds or wires in the harness" from GM - which to me reads - darned if we know.

I plan on taking the panels apart, getting at the ECM and cleaning the connections inside the car - will post any results. sure wish there wasn't so much copper in these cars!

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  • 2 weeks later...
Guest RattyOne

Final update on QDM fault - after posting on this site, I got help and found a burned out Service Engine Soon (SES) light bulb! This is in an '89 Reatta and the bulb is a stock item at any parts house.

Funny thing was that all the Buick documentation never,ever, mentioned that an instrument bulb could cause the fault!

Man it was GREAT to get that monkey off my back and silence the chimes!!!!

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Help with this if possible please????

I was un-fortunate to see the darned EO26 code appear on my coupe about a year ago (it has always appeared as a C at first, then immediately changes to a H after clearing). Better Explanation: It appears as EO26C....I clear the codes while at a standstill, and then I have a clear "NO E CODE" message..Immediately changes to EO26H as soon as I start driving and go approximately 1/2 of a mile...miles vary...I have gotten as far as several miles...I think maybe stopping the car or some other function keys the change from C to H). I have been through the FSM, spoken to 2 seater about the situaltion, and with his help addressed I would say 80% or more of the supposed faults with no success...then I saw a post about 2 months ago on the silly SES bulb thing, and with the help of someone with a 89 (keep in mind I have a 90), along with my inability to perform the VERY SIMPLE task of installing glasses on my face so I could see before I touched the electronics on a computerized automobile, I destroyed my IPC frown.gif.... smile.gif. I very intellegently tried to remove the SES bulb which I could not see was soldered in place to a circuit board with rubber tipped mini needle-nosers...

BROKE THE BULB...Yeaaa smile.gif. OH well, new /used IPC now installed, and will address the other 20% in the spring or sooner mayby if ANOTHER brainstorm occurs. Some of these probelms that set the code do not hinder the operation of the car at all.... as it is in my case. One item I have not addressed is the EGR system.....any suggestions here please?

Any help will of course be more than greatly appreciated smile.gif...

Nic

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Guest dpannell

Nic I have the exact symptoms you do.....No code until i drive for a couple miles.

I too would like to keep this thread alive.......Any chance you could share some of the potential faults passed on from 2-Seater?

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It has been a year since I communicated with him on the issue, but if memory serves correctly, I always get the basic ignition system where it should be first. I remember chating/discussing the procedures in the FSM at length, but the bulb was never brought up, and we did not get around to the EGR valve.....probably because I did not have a spare on hand....which I do now, and will address sometime in a few months/spring.

Sorry not much help at present, but I am facing the same situation as you .

frown.gif

Nic

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Back in the Summer while traveling slow on roads winding through a National Park I had the SES light come on. When I stopped I noticed the engine was running slightly rough. I checked for codes and got the dreaded E026. I pulled the FSM out of the compartment behind the seat and handed it to my wife and told her to read while I drove.

After driving and reading for couple of miles we decided it could possibly be the EGR causing the code because we did have a rough idle. We knew raw air passing through an EGR valve that is stuck partly open can be the cause of a rough idle.

We stopped again and I went back to the diagnostics screen. I went to the override section and cycled the EGR valve on and off about 25 times in each of the three stages. Then I cleared all the codes. Started the car back up and have not had the E026 code or rough idle since.

It could have been a small piece of carbon keeping one of the parts of the valve from seating properly and the opening and closing of the valve repeatedly knocked it out. OR maybe it was my lucky day. I don't know.

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Guest dpannell

TDman...I've cycled through all of the solenoids....hear them clearly, and my car runs very smooth.......However, my SES light is burnt out....

That might explain my code except for the fact that like Nic's, mine will "set" no codes until driven.....despite engine temperature.

The FSM keeps sending me back to the diagnostic aid pointing at connectors, harnesses, or damaged terminals.....

Dave

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Dave, if I were troubleshooting your problem I would not go any further until I had eliminated the SES as a source of the problem. I didn't see where you said what model you have but I'm assuming it is a 90 or 91 since changing the SES bulb in the 88 and 89 is fairly easy.

Have you tried replacing the instrument panel? If the code goes away with replacing the panel you wouldn't have to do additional troubleshooting that is not necessary.

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Guest dpannell

TDman, I agree wholeheartedly...I do have to eliminate the SES light possibility. The part that confuses me is that it will not set the code until driven...despite engine temperature. My thoughts would be that the code would set as soon as it recognized the SES bulb out. ??????

My cars down for the winter for body mounts and painting....It's going to give me a chance to go back through some connections and make certain they're good. The panel is on my list now. oh, and yeah..it's a 90'

Dave

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  • 12 years later...
On 11/13/2007 at 3:49 PM, manikmekanik said:

Hi, Jon!

QDM = Quad Driver Module = the 4 separate circuits/modules of the ECM. Each module has it's own set of sensors/system to handle. When the 4 don't all return the expected value, the QDM error code is displayed.

Best to spend some quality time with the FSM, and the diags in the car. I once solved a QDM error by replacing the ICM and coils, but would'nt suggest that as the only solution. It could be security, emmissions, crank/cam sensors, or just a bad wire in your harness. I'd need some alone-time with my FSM, and your car, to devine the precise diagnosis.

What other symptoms have you been experiencing, Jon?

Sleeplessness? Irritability? maybe even constipation, or restless third-leg syndrome?

These are all symptoms of a QDM error.

You should call your Reatta-healthcare professional, and get 'yer prescription re-filled today!

Way too funny. Thanks for the laugh. A must when dealing with ECM diagnostics and repairs. G SORENSEN   

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