GM Schematics All Rights Reserved

The essentials to run a 01227747 ECM will be listed below. Starting at the A Cavity of the GM TBI ECM: A1 is the fuel pump relay and the battery voltage trigger that activates a relay. A5 will be used to control your Service Engine Soon light (SES/ MIL). A6 is ignition power and needs to be placed to the ignition switch, A8 goes to serial data. Along with A9 – which is diagnostic test which will be accompanied on the diagnostic link connector. A11 is the “sensor” ground wire, that is shared with the Coolant Temperature Sensor (CTS) and the Throttle Position Sensor (TPS). A12 goes to ground AKA the engine block or cold hard steel.

CTS Sensor


TPS Sensor O.S.

Moving to the B connector 12 cavities and total. B1 goes to battery voltage, B2 goes to fuel pump signal B3 goes to EST reference – which is right on the distributor, B5 EST reference High – purple white in color, also goes to the distributor. B7 is ESC signal black, B10 is a park neutral switch wire, which can be grounded.

EST / HEI Distributor Small

Moving to the C and D connector 16 cavities on top, 16 cavities on bottom 32 cavities total. C3 through C6 go to the idle air control valve, C9 requires crank voltage from starter, C10 is the coolant temperature sensor signal yellow, C11 is Manifold Absolute Pressure Sensor or just (MAP) signal C13 is Throttle Position Sensor signal dark blue in color and C16 is 12 volts battery power.

MAP Sensor GM TBI | Speed Scene Wiring

MAP Sensor

Moving on to the (D) section of this connector. D1 is ground to motor, D2 is MAP sensor ground – purple in color, D4 is EST control light going to distributor, EST bypass is D5 and that is tan/black and color, oxygen sensor ground, which is the same as chassis ground. D7 is the oxygen sensor signal – going directly to the sensor, D14 is injector driver green, D16 injector driver dark – blue and color.