Chart C1 - ECM Replacement Check Chart

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In order to reduce incidents of repeat ECM failure, a revised ECM diagnostic procedure is available. Beginning in 1982, most ECMs are equipped with Integrated Circuits (IC) in place of separate transistors to operate various controlled components.

These ICs, called Quad-Drivers (QDR), have 4 separate outputs, meaning that each QDR can operate up to 4 different components. An inoperative QDR can result in ECM output becoming open or shorted to ground. Often, all 4 outputs of a QDR will fail, even if just one QDR circuit is faulty.

Refer to the following tables to determine which ECMs contain QDRs. Since this procedure is not applicable to ECMs which do not contain QDRs, those ECMs are not listed.

Performing the diagnostic flow chart will identify an inoperative QDR. Once the circuit is identified, it must be repaired to eliminate repeat ECM failure. This diagnostic procedure must be used when "Replace ECM" is the conclusion of any procedure.

ECM QDR IDENTIFICATION

Application			Output Terminals
1983-84
1226153, 1226452, 12266454, 1226455. 1226519
QDR No. 1			G, E, 6, 4
QDR No. 2			8, 19, P, P
QDR No. 3			18, 18, T, T
1985-87
226457, 1226519, 1226865, 1226866, 1227076,
1227169, 1227301, 1227855, 1228079
QDR No. 1			G, E, 6, 4
QDR No. 2			8, 19, P, P
QDR No. 3			18, 18, T, T

Fig 1: ECM Replacement Check Chart C-1

Courtesy of GENERAL MOTORS CORP.