Quad driver B No.1 error


Old 12-12-03, 04:36 AM
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Quad driver B No.1 error

I have a 1993 Buick Lesabre, 3800 engine. My GM scanner picked up a code 26 and 56, quad driver B no.1 error. Does anyone know what components this controls?
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Old 12-12-03, 04:23 PM
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Quad driver is an annoying code that usually means a dash bulb is burned out, or you have some kind of ECM fault.
Old 12-12-03, 05:19 PM
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Thanks s_ginter. Iwas beginning to wonder what it could be because the car runs fine.My heater lights have been acting a little crazy, not working sometimes. Thanks.
Old 12-12-03, 07:15 PM
Join Date: Apr 2002
Location: Pittsburgh,Pa
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Put an ECM in it.Light bulbs don't cause quad driver codes.1992 to 1995 ECM's in a word sucked.If it runs ok leave it alone.You will need to test every solenoid and relay on the car related to the ECM.20 OHMS OR MORE.Suggest you do this from the ECM connectors as a short in the wire between the ECM and related components will cause a repeat failure.You will need a wiring diagram for your car to proceed.A little generic test,make sure your heater is off and the engine is cold and turn the key on but don't start the car is the coolant fan running?If it is the ECM is cooked.
Old 12-13-03, 11:29 AM
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Each quad driver operate a maximum of 4 components. You will need a schematic to determine which components. You will have to ohm test both the components and the related wiring back to the ECM. TCC solenoids are pretty notorious but since you recently replaced a motor mount I'd look closely at the wiring anywhere near there.
Old 12-13-03, 12:33 PM
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Thanks alot Davo, and Desi. I will try that generic test out too.
Old 12-13-03, 01:19 PM
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Check the torque converter solenoid resistance and the second gear switch. Most likely.
Also the canister purge solenoid, the "temp" lamp, the low speed fan relay. look for any symptoms to point you in the right direction. clear codes drive the car and see which code comes back first. Very good chance it is the ECM
Old 12-14-03, 05:18 PM
Join Date: Dec 2002
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I've had several vehicles with QDM Faults and sometimes it is the ECM, but don't just assume it is. If it's not you wasted your $$. The codes 26 and 56 are for 2 different failures. QDMA and QDMB.

QDMB Controls shift solenoids a & b, EGR solenoids, and TCC pulse width modulation Solenoid.

QDMA Contols the low speed fan, the evap purge, temp light, and tcc apply.

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