What fuses power the PCM and fuel pump circuits on the 5.8L engine?

Three 20A fuses in the Engine Compartment Fuse Box: fuse U (hot in Start or Run) feeding the PCM power diode, and fuses I and O (hot at all times) feeding the PCM power relay and fuel pump relay circuits.

What wire feeds the fuel pump from the fuel pump relay?

Circuit 926, a light blue/orange (LB/O) wire, runs from the fuel pump relay through connector C198 to the fuel pump motor, showing 12V when the relay is energized.

Where does the inertia fuel shutoff switch circuit go?

Circuit 238 (dark green/yellow, DG/Y) runs through splice S139 and connectors C202 and C185 to the inertia fuel shutoff switch; the circuit continues on page 25-6.

What does the PCM control according to this diagram?

The Powertrain Control Module receives inputs from various sensors and uses the information to control fuel flow, Exhaust Gas Recirculation (EGR), ignition, transmission controls (with E4OD), and evaporative emissions.

What ground circuits does the PCM use in this diagram?

Circuit 57 (BK) grounds at G100 and G104, and circuit 570 (BK/W) runs through splice S106 to ground G101. Ground details are referenced on pages 10-1 and 10-3.

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Ford 5.8L Engine Controls Wiring Diagram 25-1 - PCM & Fuel Pump Relay Circuits

Engine Controls wiring diagram, 5.8L, page 25-1, PCM power relay and fuel pump relay circuits

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Ford 5.8L engine controls wiring diagram showing PCM power relay, fuel pump relay and engine compartment fuse box circuits.

AI caption August 2018 · Photo 373 of 386

This document is page 25-1 of a Ford factory-style wiring diagram covering Engine Controls for the 5.8L engine. It shows the power feed circuits from the Engine Compartment Fuse Box (three 20A fuses at positions U, I, and O; fuse U hot in Start or Run, the others hot at all times) to the PCM Power Diode, PCM Power Relay, and Fuel Pump Relay. Circuit numbers and wire colors are labeled throughout, including 175 BK/Y, 37 Y, 361 R, 926 LB/O (fuel pump feed), 238 DG/Y (to the inertia fuel shutoff switch, continued on page 25-6), 912 W/R (to the E4OD transmission, page 30-2), 570 BK/W and 57 BK grounds, plus 209 W/P, 914 T/O, and 915 PK/LB going to VIP data link connectors. Splices (S102, S106, S136, S139), connectors (C101, C185, C198, C199, C202), and grounds (G100, G101, G104 with references to grounds pages 10-1 and 10-3) are identified. Explanatory callouts describe the PCM Power Relay directing voltage to the PCM and fuel pump relay, the fuel pump relay directing voltage to the fuel pump, and the PCM's role controlling fuel flow, EGR, ignition, E4OD transmission, and evaporative emissions. Voltage test values (0V/12V relay energized) are noted at relay terminals.

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Frequently asked questions

What fuses power the PCM and fuel pump circuits on the 5.8L engine?: Three 20A fuses in the Engine Compartment Fuse Box: fuse U (hot in Start or Run) feeding the PCM power diode, and fuses I and O (hot at all times) feeding the PCM power relay and fuel pump relay circuits.
What wire feeds the fuel pump from the fuel pump relay?: Circuit 926, a light blue/orange (LB/O) wire, runs from the fuel pump relay through connector C198 to the fuel pump motor, showing 12V when the relay is energized.
Where does the inertia fuel shutoff switch circuit go?: Circuit 238 (dark green/yellow, DG/Y) runs through splice S139 and connectors C202 and C185 to the inertia fuel shutoff switch; the circuit continues on page 25-6.
What does the PCM control according to this diagram?: The Powertrain Control Module receives inputs from various sensors and uses the information to control fuel flow, Exhaust Gas Recirculation (EGR), ignition, transmission controls (with E4OD), and evaporative emissions.
What ground circuits does the PCM use in this diagram?: Circuit 57 (BK) grounds at G100 and G104, and circuit 570 (BK/W) runs through splice S106 to ground G101. Ground details are referenced on pages 10-1 and 10-3.