Chart C1: ECM Quad-Driver Check
To energize controlled devices, the ECM uses integrated circuits called "QuaD-Drivers" in place of separate transistors. Each QuaD-Driver has 4 separate circuits that can be turned on or off independently. The ECM used on this vehicle (part No. 1227302) does not have fault protection, therefore, a single faulty circuit many times causes all 4 QuaD-Driver circuits to fail. Because of increased current flow, 2 QuaD-Drivers are used to drive the Torque Converter Clutch (TCC) solenoid. A faulty circuit is the largest cause of a failed QuaD-Driver, therefore, this check should be performed whenever instructed to "Replace ECM" or whenever ECM exhibits characteristics of a damaged QuaD-Driver, such as the following:
- "SERVICE ENGINE SOON" light on, with no stored codes.
- Engine will not start and/or ECM will not flash Code 12.
- Flickering, intermittent or dim "SERVICE ENGINE SOON" light.
- Output, such as the TCC, is inoperative or constantly "on".
- Engine misfires, surges or stalls.
- "Scan" tester is erratic or inoperative.
ECM NO. 1227302 QUAD-DRIVER IDENTIFICATION
| QDR Number | ECM Output Terminal | Circuit Controlled |
|---|---|---|
| 1 | A2 | A/C Relay Control |
| 1 | A4 | EGR Control |
| 1 | A5 | SES Light |
| 2 | A3 | Cannister Purge Solenoid |
| 2 | D2 | Coolant Fan Relay |
| 3 | A7 | Shift Light (Man. Trans.) TCC Control (Auto. Trans.) |
| 3 | C2 | Air Divert Solenoid |
NOTE:
Use this check procedure only after other diagnostic charts have determined that there was an ECM failure.