What is code 56?

1993 OLDSMOBILE 88
225,000 MILES • 3.8L • V6 • 2WD • AUTOMATIC
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MASONERS
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Car will crank and run for 5 to 10 seconds and dies slowly like it running out of gas.
Jan 4, 2025 at 4:41 PM
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STRAILER
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a Code 56 in the OBD-I (On-Board Diagnostics) system generally refers to an issue with the Quad Driver Module (QDM) in the Powertrain Control Module (PCM). So, it looks like the ECM is bad. I would get a rebuilt unit by searching eBay or Google. Here are the instructions on how to do the job. Check out the images (below). Please let us know what happens.
Jan 5, 2025 at 3:10 PM
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MASONERS
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I went and an ECM but still didn't fix problems it's still cranking and running for 10 to 15 seconds and shutting off like it's running out of gas or starving for air.
Jan 5, 2025 at 3:15 PM
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I would do the ignition module and coil pack next, they don't say anything more about the code but I have seen the ignition module cause this problem. Can I ask if the security light is flashing when you try to start it?
Jan 6, 2025 at 9:54 AM
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MASONERS
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I've already put an ignition module on it already and no, the security light isn't flashing. The only thing the does is, it'll crank and run good for 10 to 15 seconds and shuts off like it's running out of gas or starving for air because when it does it I try giving it gas and you can hear it sucking a lot of air like it isn't getting any or gas.
Jan 6, 2025 at 10:01 AM
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Can you use starting fluid after or during when it stalls to see if that changes anything?
Jan 6, 2025 at 10:10 AM
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MASONERS
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I can but I don't have to because it'll crank right back up itself and run again 15 to 20 seconds and shut off again but every time soon as it shuts off it'll crank right back like nothing wrong but shuts off.
Jan 6, 2025 at 10:13 AM
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STRAILER
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When the engine is stalling spray starting fluid to see if it will keep running, if so then you know it is a fuel issue, also this car might have an oil pressure switch that will cut off the fuel pump if you have no oil pressure, you might want to bypass the switch to see if that is a problem.
Jan 6, 2025 at 10:44 AM
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MASONERS
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I've tried that spraying it and it want when it starts shutting off it shuts off, but cranks right back. I'll check for oil pressure switch and see.
Jan 6, 2025 at 11:06 AM
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Okay, how about the security light is that flashing?
Jan 7, 2025 at 10:20 AM
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MASONERS
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I ran codes it said throttle position sensor low voltage and (MAF) mass air flow sensor circuit and quad driver module b and quad module driver circuit.
Jan 7, 2025 at 11:11 AM
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The Quad Driver Module (QDM) is part of the ECM and controls various solenoids and relays, such as:

EGR solenoid
Coolant fan relay
EVAP purge solenoid
TCC (Torque Converter Clutch) solenoid

So you may have a shorted relay or sensor I would start unplugging EVAP and EGR solenoids to test them manually. Also test the sweep of the TPS sensor.
Jan 9, 2025 at 10:19 AM