i just bought my 94SSE back for my mom and this is the code. it is running so rough, but since changing the plugs and wires, it at least idles(badly but it does) and when driving it, when at drivign speeds, it runs fine, just when u stop or are at idle does it just run like crap. please give me something else to check

QDM1 stands for "quad driver module 1". This code is usualy a result of a failed control module. Quad drivers are "sections" of a control module, for example, there can be 4 or more quad driver modules in one computer and they are always refered to in numerical order. QDM 1 may control cooling fans, QDM 2 may control A/C clutch opperation, QDM 3 may control EGR opperation and so on.

I would be leaning toward a faulty ECM.

fatcat gave a great description of the QDM but I wouldn't go out looking for a replacement PCM just yet. To add to the above description, the QDM is the part of the PCM that provides a LO (ground) output to certain accessories like relays, solenoids and indicator lamps. Most of the time, there are more than one accessory driven by a particular QDM. For example, my 93 has QDM A which controls the canister purge solenoid, Temp lamp, LO speed fan relay and TCC apply solenoid and QDM B which controls the three EGR solenoids and three different trans shift solenoids. Yours will be structered a little different as your 94 PCM is different but you can get the idea. Unfortunately, the PCM doesn't pinpoint the exact circuit that is having the problem.

If you have the luxury of having a spare PCM, by all means try that first as this can save a lot of troubleshooting but most don't have them laying around. By your description of the problem, it could be a faulty EGR valve or shorted EGR wire. Someone with a 94 manual should look up exactly what circuits are controled by the QDM 1 though.

I think 94 is the same as 95.. QDM 1 relates to TCC solenoid, evap purge soleniod (charcoal canister) and boost soleniod.

With your car running rough at idle and stops I'd hold off on the QDM failure for a couple minutes and start checking all the vacuum lines. The most common line to fail is directly under your airbox. A vacuum line comes from the motor to the charcoal canister/evap purge sol (part of QDM 1 see where this is going?).

It'* a simple piece of rubber hosing that connects the lines together. Being that these cars are aging, the rubber is starting to get brittle. Even my 97 and SSESC'* 97 had this exact same issue. I'd check all the lines you can find including the ones that go other places. It'* a super cheap thing to fix. I think 4 feet of rubber vacuum lines (I got 2 sizes) cost about $3

search.....ladee daadee daa!

ok replaced those lines and still to no avail. it will fire up as soon as the key is turned. will hold an idle, although rough as hell, and when running down the road its fine. This is about to drive me nuts. could it be the coil pack? im wondering cause it sounds like a miss almost, but the plugs and wires are new and it didnt help anything when i changed them.

Sounds like testing the coils would be your next item. When it'* running rough you don't hear air sucking sounds like vacuum leak do you?

just the cone filter suckin in air, thats all ican hear. it almost feels like a spark miss, so, i guess the next item on agenda is the coil pack

ok newest updates, i went to the junk yard and bought a coil pack with the ignition module, changed it out car will not even run and there is no spark at all coming from the coil pack, so what granddad is thinking is that (remember the accidental pole hitting) when he had to splice all the wires to the harness back together that one of the splices came undone when i loosened the bolt that holds the connector on, so i am getting a new harness with longer whires and we are going to resplice them and see what happens. keep in mind that she started and idled*crappy* but idled before i changed the coil pack so we think this has to be the problem, and yes we did put the original back on. i will let ya'll know the updates as they arise!!

Even with all this, i am so glad to have my bonne back in the family!! I ll get to drive it everyonce in a while, i like my GP GTP alot!!

OK, latest update, i broke the wiring harness when unbolting it from the coil pack so we had to resplice all the wires with a new harness and then the new coil pack works good. it starts, runs, idles, and has lots of get up and go, however, the idle is still rough, what could be the cause? Please help.