Engine Control Module (ECM)

ECM consists of a microcomputer, inspection light (Red LED), diagnostic test mode selector, connectors and wiring for voltage signal input, voltage signal output and power supply. See ECM LOCATION table. Unit is not serviceable and should not be opened. Inspection light (Red LED) is provided on side of unit so system operation can be checked. ECM contains memory and logic circuits, which enable it to interpret sensor inputs and control various engine systems.

Fused battery power is provided to ECM terminal No. 20 (Purple wire) when ignition switch is in Start position. Continuous fused battery power is provided to ECM terminal No. 58. Battery power to drive ECM internal components is provided through ECCS relay, which is energized by ECM when ignition switch is turned to ON position.

ECM LOCATION

Application	Location
G20	Under Dash, Behind Center Console

NOTE: ECM components are grouped into 2 categories. The first is INPUT DEVICES, which are components that control or produce voltage signals monitored by ECM. The second category is OUTPUT SIGNALS, which are components controlled by ECM.