Chart C-1 ECM Quad Driver (QDR) Check

Chart C-1 ECM Quad Driver Check:

ECM Quad Driver Application Chart:

CHART C-1 ECM QUAD DRIIVER CHECK (QDR)

DESCRIPTION

Many ECM's use an integrated circuit (IC) instead of individual transistors to operate different components that are controlled by the ECM. These IC's are called QUAD DRIVERS (QDR's). Each QDR has 4 seperate outputs so it can operate 4 different items independently.
As an example, one QDR may operate the check engine light, the canister purge solenoid, the EGR solenoid and the A/C relay. The QDR is not always connected to 4 different outputs. Where more current flow is required (such as the TCC solenoid or M/C solenoid) 2 of the outputs may be used to drive the same device.
A bad QDR normally causes an ECM output to go open or shorted. Often all 4 outputs will not operate even if only 1 circuit is faulty.

TESTING NOTES

1. This procedure will not test all ECM operations. It will determine if a circuit caused the ECM QDR to fail.
2. Because the most common cause of QDR failure is faulty vehicle circuits you are urged to use this procedure whenever an ECM is replaced, especially when:

a. The CHECK ENGINE or SERVICE ENGINE SOON lamp is on and no trouble codes are stored.
b. The engine will not start and/or the ECM will not flash code 12.
c. Dim, flickering or intermittent CHECK ENGINE lamp.
d. An output is non-operative or "ON" at all times (such as TCC).
e. Scan tool will not operate.
f. Engine misfires, stalls or surges.


This procedure will not only find the damaged QDR, it will usually find the circuit that caused the damage to the ECM.