Dec 7, 20071993 MKIV Toyota Supra E85 Project- Sep 2007
The B1 connector, or "THE BIG YELLOW CONNECTOR, near the ECU"
There are 5 wires you will use grom this connector
BLACK/WHITE - Large 10 guage Black with a white stripe - Starter (depending on year, AT/MT, this could have a white or blue stripe)
Black/orange - Large 10 or 12 guage black with a orange stripe - Needs switched power. This runs directly from the ignition switch, and powers your injectors, coil, and igniter.
Black/orange - Small 16 guage black with orange stripe. This also needs switched power. This could be tied into the Large black/orage wire.
Green - (FC on ECU) - Green wire - This controls ground the Circuit Opening Relay
yellow - (FP on ECU) - Yellow wire - NOT NEEDED! this is used to reduce the voltage on the fuel pump, but is not neccesary.
This is the wire that goes to the starter solenoid. It is located in the center part of the connector. In a manual, this will travel from the ignition switch, through the clutch switch, through the starter relay, then through this connector. Automatics are a little more difficult. If you do have an auto wiring harness, the starter wire run through the engine harness, to the tranny harness under the intake manifold. You will need to cut and splice the wires togother in order to complete the loop to feed power to the starter solenoid. The auto will usually use a Black/White wire, and the manual will use a Black/Blue wire. In some vehicles such as the 85-older supra's, and I have noticed older model pickups, that this wire goes through tho body harness. If this is the case, you will have to figure out where that is, splice into it, and run it to this connector. On newer vehicles the starter will run through the engine harness.
This is a large black wire with an orange stripe. Along with the starter, these are the two center wires in this connector. You have to have switched power to this wire in order to supply power to your injectors, coil, and igniter. This usually comes through the ignition, and requires at least 15 amps. In other words, don't use the power from your radio.
Circuit Opening Relay(Ground)
The green wire coming from the FC signal from the ECU, controls the ground on the Circuit Opening Relay. As long as there is power to this relay(which is discussed on the C1 connector), power will then travel to the fuel pump, or Fuel Pump Control Relay. This allows your fuel pump only to turn on when the engine is running. When the engine stops running, the ECU will cut the ground signal to this wire, which will turn off the Circuit Opening Relay, and no longer supply power to the fuel pump.
Fuel Pump Control Relay(Ground)- This is for the resister, and is not needed
This yellow wire from the FP signal on the ECU, is used for a dual speed fuel pump setting. The ECU will supply a ground to the Fuel Pump Control Relay, which will then change the resistance on the power going to the fuel pump. The relay and resistor is located on the passenger side strut tower. I have run many swaps without this component, and have not seen any impact on fuel economy or peformance.