*****IMPORTANT*****Note that the wire color layout diagrams accompanying each picture are as seen FROM the CONTROL HARNESS SIDE of the connector with the release tab (for a male side connector) or locking notch (for a female side connector) on top. That is, you are looking at the wires going into the connector, OPPOSITE the side that is pictured. Like this: How to identify ECU pin numbers. ******************* As we all know, the 1990 model year had many quirks to it when compared to the later model 1Gs. Because this was a single (and the first) year of the Eclipse/Talon/Laser trio, information on these cars isn't nearly as abundant as 1991-1994 models. I don't plan to dive into and explain the differences between these models as there are plenty of threads around naming the differences. In short, this article is a configuration diagram. It aims to familiarize members with the 1990 4G63 turbo engine control harness electrical connections, similar to what snowborder714 did in his 2g Engine Bay Electrical Connections article, but not nearly as thorough. To be clear, this article does not cover every electrical connection in the 1990 engine bay, only those on the engine control harness, including the handful of interior connections. NOT THE HARNESS YOU'RE LOOKING FOR? SEE ALSO: The 1990 Engine COMPARTMENT Wiring Harness. As a couple extras, it will touch on some connector differences that must be attended to when swapping a 1990 turbo engine control harness into a later model 1G or vice versa (these are denoted by **). It lists original wire colors and original individual wire locations as viewed from the wire side of the connector as well as a visual of each connector on the harness. Also, for comparison, here is a similar page for the later model 1Gs (those connectors labeled with * are either completely different, in a different location, or non-existent on the later model 1Gs): 1Gb DSM 4G63 Turbo Wiring Harness Diagram First and foremost, the main harness itself. The alphanumeric identifiers relate to those in the 1991 configuration diagram found in the electronic copy of the factory service manual: Download the 1G Service Manuals. The harness displayed here is a 1990 turbo engine harness which, by consequence, means it is from a vehicle with a manual transmission. Click to enlarge slightly or zoom by pressing Control and + (the plus sign): To shrink, press Control and - (the minus or negative sign). A-08: Dual Pressure Switch A-09: Wiper Motor A-10: Control Wiring Harness and Battery Cable Assembly Combination *A-11: Auto-Cruise Control Vacuum Pump A-12: Brake Fluid Level Sensor A-13: Control Wiring Harness and Solenoid Valve Harness Assembly Combination A-36: Air Flow Sensor A-51: Waste Gate Solenoid A-52: Control Wiring Harness and Engine Compartment Wiring Harness Combination A-53: Control Wiring Harness and Engine Compartment Wiring harness Combination A-55: Fuel Pump Check Connector A-56: Noise Condenser A-57: Defogger Relay A-58: Injector Resistor Pack A-59: Engine Speed Adjustment Connector A-60: Ignition Timing Adjustment Connector *B-00: Noise Filter (for Tachometer) B-01: Injector No. 4 *B-02 & B-05: Throttle Position Sensor and Idle Switch **B-04: Idle Speed Control Actuator B-06: Injector No. 3 B-07: Detonation (Knock) Sensor B-08: EGR Temperature Sensor B-09: Injector No. 2 B-10: Injector No. 1 *B-14: Ignition Coil (Coil Pack) *B-15: Power Transistor Unit B-16: A/C Magnetic Clutch B-26: Oxygen Sensor B-29: Engine Coolant Temperature Gauge Unit B-30: Engine Coolant Temperature Sensor (for ECU) B-31: Engine Coolant Temperature Switch (for A/C) *B-32: Crank Angle and Top Dead Center Sensor (Cam Angle Sensor, CAS) C-56: Oxygen Sensor Check Connector C-57: Control Wiring Harness and Body Wiring Harness Combination (1-pin, passenger side kick panel) **C-58: Control Wiring Harness and Body Wiring Harness Combination (14-pin, passenger side kick panel) C-59: Control Wiring Harness and Body Wiring Harness Combination (6-pin, passenger side kick panel) C-63: MPI Control Relay C-64: MPI Control Unit (ECU, small connector) C-65: MPI Control Unit (ECU, medium connector) **C-66: MPI Control Unit (ECU, large connector) **C-67: Control Wiring Harness and Body Wiring Harness Combination (under center console) The wire color layout diagrams accompanying each picture are as seen FROM the HARNESS SIDE of the connector with the release tab (for a male side connector) or locking notch (for a female side connector) on top. They should be color coded correctly, but if there is a disagreement with the letters and the color of the letters, go by the letters. When two colors are listed together, the first is the main color and the second is the color of the stripe or tracer. The letters represent the following colors: B - Black W - White R - Red G - Green L - Blue Y - Yellow O - Orange Lg – Light Green PM me if you find any errors and I will make corrections as necessary. Finally, the following supporting vendors supply the individual connectors linked or partial kits for different model year DSMs: JNZ Tuning Extreme PSI Magnus Motorsports At the end of the day, they are all coming from Sheridan Engineering.