What is code 56?

Tiny
MASONERS
  • MEMBER
  • 1993 OLDSMOBILE 88
  • 3.8L
  • V6
  • 2WD
  • AUTOMATIC
  • 225,000 MILES
Car will crank and run for 5 to 10 seconds and dies slowly like it running out of gas.
Saturday, January 4th, 2025 AT 4:41 PM

11 Replies

Tiny
KEN L
  • MASTER CERTIFIED MECHANIC
  • 50,162 POSTS
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.
Images (Click to make bigger)
Thumb
Thumb
Thumb
Was this
answer
helpful?
Yes
No
+1
Sunday, January 5th, 2025 AT 3:10 PM
Tiny
MASONERS
  • MEMBER
  • 6 POSTS
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.
Was this
answer
helpful?
Yes
No
Sunday, January 5th, 2025 AT 3:15 PM
Tiny
KEN L
  • MASTER CERTIFIED MECHANIC
  • 50,162 POSTS
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?
Was this
answer
helpful?
Yes
No
Monday, January 6th, 2025 AT 9:54 AM
Tiny
MASONERS
  • MEMBER
  • 6 POSTS
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.
Was this
answer
helpful?
Yes
No
Monday, January 6th, 2025 AT 10:01 AM
Tiny
KEN L
  • MASTER CERTIFIED MECHANIC
  • 50,162 POSTS
Can you use starting fluid after or during when it stalls to see if that changes anything?
Was this
answer
helpful?
Yes
No
Monday, January 6th, 2025 AT 10:10 AM
Tiny
MASONERS
  • MEMBER
  • 6 POSTS
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.
Was this
answer
helpful?
Yes
No
Monday, January 6th, 2025 AT 10:13 AM
Tiny
KEN L
  • MASTER CERTIFIED MECHANIC
  • 50,162 POSTS
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.
Was this
answer
helpful?
Yes
No
Monday, January 6th, 2025 AT 10:44 AM
Tiny
MASONERS
  • MEMBER
  • 6 POSTS
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.
Was this
answer
helpful?
Yes
No
Monday, January 6th, 2025 AT 11:06 AM
Tiny
KEN L
  • MASTER CERTIFIED MECHANIC
  • 50,162 POSTS
Okay, how about the security light is that flashing?
Was this
answer
helpful?
Yes
No
Tuesday, January 7th, 2025 AT 10:20 AM
Tiny
MASONERS
  • MEMBER
  • 6 POSTS
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.
Was this
answer
helpful?
Yes
No
Tuesday, January 7th, 2025 AT 11:11 AM
Tiny
KEN L
  • MASTER CERTIFIED MECHANIC
  • 50,162 POSTS
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.
Was this
answer
helpful?
Yes
No
Thursday, January 9th, 2025 AT 10:19 AM

Please login or register to post a reply.

Related OBD1 Code 56 Content