rich_e777 Posted April 30, 2023 Report Share Posted April 30, 2023 1994 Olds Cutlass 3100. Viewing the data from an Actron(I know I know its not a Tech 1, just a code reader and data viewer/recorder) tool it lists Quad Drivers 1-4 and its showing 1 and 4 are bad but 2 and 3 are ok. Ive been in the big manual for an hour and cannot really figure out what they do and I have no cooling fans and A/C clutch isnt coming on. Trying to determine if the issues are related. A search brought me to an old 2007 thread with the only info I could find. Quote Link to comment Share on other sites More sharing options...
Schurkey Posted April 30, 2023 Report Share Posted April 30, 2023 I've never dicked with quad drivers. Yes, that could be the problem with your electrical accessories not working. Kinda depends on whether the failed QD activate those accessories. I'd expect that to be in the service manual; wiring diagrams probably--but I've never needed to look that up. I suppose you could solder new QD into the ECM, but it's probably easier to replace the ECM and see what happens, AFTER you assure that those accessories aren't drawing excess current. Kinda guessing the QD turns on a relay, which turns on the accessory. So it'd maybe be problems in the wire harness to the relay, rather than the accessory itself. White93z34 and rich_e777 2 Quote Link to comment Share on other sites More sharing options...
White93z34 Posted April 30, 2023 Report Share Posted April 30, 2023 In the absence of any further information, what i would do is manually either trigger the relays for the fan or remove the relay and jump it that way. just to see if the fans work. It would be great if you had a tool that could command the fans on, but alas. the next best thing you could do is prove either the relay socket or probe near the PCM when the car should be commanding the fans and verify that. That all said, I cannot base this on anything short of "but I remember this being an issue back when on the forum" but I seem to remember people having issues with QDMs on the 94/95 PCMs I believe Schurkey is on the right path about the QDMs being what provides power to the relay in order to trigger it. rich_e777 1 Quote Link to comment Share on other sites More sharing options...
55trucker Posted April 30, 2023 Report Share Posted April 30, 2023 Generally a quad driver issue showing on ones scanner is due to a possible short in the circuit that the quad (transistor) is controlling. The *failed* quad is the result of the issue not the source. One needs to test the circuit the driver is controlling for opens or shorts. The PCM is not necessarily the root problem. rich_e777 1 Quote Link to comment Share on other sites More sharing options...
rich_e777 Posted April 30, 2023 Author Report Share Posted April 30, 2023 (edited) Awesome info guys, Thank You. That gives me something to use against the flow chart in the manual. I may have separate issues so I`ll focus more on the cooling fans and pcm. Low A/C psi according to the sensor and if I read correctly that A/C sensor reading a low psi interrupts the process of grounding the relay, I think... I`ll come back to the A/C system when I have the gauges to test it better. Edited April 30, 2023 by rich_e777 Quote Link to comment Share on other sites More sharing options...
White93z34 Posted April 30, 2023 Report Share Posted April 30, 2023 yeah low refrigerant pressure would prevent the compressor from running Quote Link to comment Share on other sites More sharing options...
rich_e777 Posted June 3, 2023 Author Report Share Posted June 3, 2023 (edited) Ok I did some testing and here is what I know. KOEO V is about 13.8 Jumping both cooling fan relays turned both fans on after confirming power to each relay cavity. Also I can see the request for A/C ON is given on the scan tool which should have the fans running as well. Based off what I`m reading from the manual the pcm should ground circuit 335(473) to activate Fan 1(2) when A/C command is ON but that doesnt seem to be happening. A test light connected to battery - will activate the fan when probing either relay circuit and work both relays as well. So fan motors work, the relays click as they should, the wiring associated between relays and fans seem to be ok aside from the circuit between the pcm and relay not grounding. Visibly the harness is ok, still wrapped up in the factory tape all the way from the fuse box. Schematic for reference I`m a bit stuck now in which direction to go and what to look at. Edited June 3, 2023 by rich_e777 Quote Link to comment Share on other sites More sharing options...
rich_e777 Posted June 8, 2023 Author Report Share Posted June 8, 2023 I found it, there was nothing else to check because everything is fine. Just me misunderstanding how my own car of 17 years works and not reading the tool right. I let the engine idle and the temp stopped going up at 190F, fans dont come on til 223-6F. Refrigerant was low and I believe leaking but I can get 25lbs at idle and it kicked the compressor on. With the A/C compressor spinning cooling fan 1 came on just as it should. Quote Link to comment Share on other sites More sharing options...
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