88 GT
3800SC1 w/4t60e from 1995 oldsmobile 88 OBD 1.5

My fiero started acting funny and going into limp mode the other day and gave me the check engine light.
pulled the codes and got P1650-QDM2 failure and P0134-HO2S circuit open

I haven't looked into the HO2S code yet, I believe it is just wiring since I replaced the sensor a couple weeks ago.

I do need some help with the QDM2 failure code though. I have been trying to look into it, Quad Driver Module 2, does anyone know which 4 circuits this contols? I think it is in the transmission. I haven't found a problem in the wires, but since I don't know exactly which ones to look at I have only checked a few. I replaced the PCM with a spare I had and that didn't change anything.

It started happening 2 days after I fixed my last issue which was a dying crank sensor, I replaced that as well as removed, inspected and reinstalled the engine bay wiring harness.

Anyone have any suggestions or where to look to pinpoint the issue?
Thanks

Anyone?

Quad drivers control actuator outputs like shift solenoids and egr solenoids etc.

I am not entirely positive but I *think* the qdm2 on your PCM controls trans outputs, 3 shift solenoids and the TCC solenoid. I could be wrong though, the best thing to do would be to find information on the vehicle your PCM came from and verify.

If it is in fact the ones I posted, start by disconnecting the TCC solenoid from the trans and clear the code out to see if it goes away.

Basically, when a qdm code sets it is caused by a problem with a solenoid that it controls, usually from high resistance or too low resistance (a short). Sometimes the fault can overheat the qdm in the PCM, causing a bad PCM as well so its usually a good idea to replace that at the same time.

-Joe

QDM2 only monitors the shift solenoid circuits (Shift Sol. A and B). That's it.

This code will set if there is a problem with the shift solenoids, wiring, OR if the transmission loses ignition 12v + power. If you are running a heated O2 sensor and the sensor's heating element shares the same circuit as your transmission, this could be the cause of both codes/problems. So that is where I would look first.

-ryan

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A QDM controlled item, such as a shift solenoid receives 12V directly from the fuse box. The other wire from that item goes to the Quad Driver inside the ECM, where it grounds that terminal to operate that solenoid.

The ECM is smart, it is watching the voltage at the Quad Driver output. In theory it should see the 12 Volts from the fuse box coming through the solenoid, and it should see the voltage drop to zero when the quad driver grounds it. If either of these events fail to occur, the code is set.

So if the fuse, the wiring or the solenoid fails (or is just disconnected) 12V will not make it back to the ECM. That will set the code.

If the Item is shorted, the quad driver will fail or overheat, and the 12V may not get completely pulled to ground, the ECM will see that and also send a code.

Heres a great way to check for problems:
First and most important, confirm that your fuses are good. If a certain fuse goes, that will guarantee this code to get set.
Disconnect the ECM and turn on the ignition, use a volt meter to meter the pins that connect to the items that are controlled by the quad driver to see if there is 12V present at those pins. If there isn't, you'll have to check your harness and the controlled Items further. This will eliminate the ECM as the culprit. However, since I do not have drawings, I cannot tell you which pins to check.

Hope this helps.

Thanks for the responses, I will go out and see what I can get done tonight.

So I should have +12V with ignition on at terminals BE14 and BE15 yes?
wiring

Would grounding these wires activate the solenoids? If so, and it won't do any harm, would they make any sound I can listen for to see if they are working?

I did have the wiring harness out so it is possible I missed a connection somewhere or blew a fuse by grounding a wire. I will check for those first.

quote Originally posted by D_sensitized: Is there a way to test the solenoid without a scan tool?

You can do a resistance test. Turn the ignition off and unplug the PCM. You'll need to tap into the power circuit you have feeding the transmission's pin E with one of your digital ohm meter's probes. The other ohm meter probe you'll need to connect to the shift solenoid wires coming to pins BE14 and BE15. The resistance you should see should be between 19 and 31 ohms, or very close to that range for each solenoid. If you don't get these results, unplug the transmission's electrical connector and probe the terminals with your meter directly, at the transmission. Measure resistance between pins A and E for Shift Solenoid A and pins B and E for Shift Solenoid B. You should get between 19 and 31 ohms. If not, it is probably a solenoid or internal transmission wiring issue.

Let us know what you find.

K, I checked the resistance at the computer plug and got 22.7 ohms on each one.
So I have proper resistance and voltage going through each one.
I've tried 2 ECMs and that didn't change anything.

Also, around the time this started happening, after replacing my crank sensor( I was also fiddling around with interior wires fruit to find that issue) one of my dome lights would stay on. I removed the bulb and when I put it back in after this issue got worse it was working fine. Only the right side of the 2 center most bulbs was stuck on, the other worked normally. (the ones attached to the door switch, not the dome switches). Is that just a coincidence or do those wires ever come near the trans wires. Trans gets power from pin K of the C203 connector.

In late May, one of the trans cooler lines popped off and dumped out all my fluid, I had to coast down the hill a couple blocks back home, would that have caused any issues? I forgot about it until now and it's been my daily driver with no issues since.

I don't have an ECM schematic in front of me, Perhaps QDM2 does more then just those two solenoids?

Does anyone have ECM diagrams for this car? (1995 oldsmobile 88)
I still can not find the issue and don't really know where else to look or what to check.

Anyone else ever had this happen or know how to help? This really sucks.

Well today I changed the trans fluid, even though it was only a couple months old, I got to look inside. Didn't see anything out of the ordinary.
I noticed the gear selector switch under the leaver on the trans was slightly out of alignment, (the reverse lights came on at the wrong times when shifting) so I adjusted that.

I took it for a test drive and it drove fine. Still not too sure about it so I won't be taking it to and from work until I drive it around some more to see if it comes back.

Would the gear selector being out of alignment cause this? Could it possibly make the computer think it is in another gear when the trans is in drive?