What does the PCM power relay do on the 1996 5.8L engine?

Per the diagram callout, it directs voltage to the PCM, fuel pump relay, and PCM-related components. It is fed by a 20A fuse (position 9) that is hot at all times, with a start/run feed through the PCM power diode on circuit 175 BK/Y.

What wire feeds the fuel pump relay?

The fuel pump relay is fed through a 20A fuse (position 16) on circuit 37 Y (hot at all times). When energized it outputs +12V on circuits 926 LB/O and 238 DG/Y, directing voltage to the fuel pump.

What connector is the Mass Air Flow (MAF) sensor on and what wires connect to it?

The MAF sensor is at connector C130, with wires including 967 LB/R, 968 T&B, and 361 R power (relay energized).

How is the PCM grounded in this diagram?

PCM pins 24, 51, 76, 77 and 103 use 570 BK/W wires that join at splice S101 and go to ground G101; a 57 BK circuit runs to ground G100.

What does the EVAP canister purge valve do according to this diagram?

It allows gasoline vapors into the engine to be burned; a charcoal-filled canister collects and stores vapors from the fuel tank. It connects through C129 on circuit 191 LG/BK.

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1996 Ford Bronco 5.8L Engine Controls Wiring Diagram - PCM & Fuel Pump Relay

Ford 25-1 Engine Controls 5.8L wiring diagram, page 96, with PCM power relay, fuel pump relay, MAF sensor and EVAP canister circuits

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Wiring diagram of 5.8L engine controls showing PCM, fuel pump relay, EGR and EVAP circuits with color-coded wires and connector callouts

AI caption July 2017 · Photo 242 of 386

This document is page 25-1 of a factory-style wiring diagram titled "Engine Controls, 5.8L," marked "96," showing the engine control power distribution circuits for a 5.8L engine. It depicts the engine compartment fuse box feeds (fuse 22 20A hot in start or run; fuses 9 and 16, 20A each, hot at all times) supplying the PCM power diode, PCM power relay, and fuel pump relay. Wire circuit numbers and colors are labeled throughout, including 175 BK/Y, 37 Y, 361 R, 926 LB/O, 238 DG/Y, 57 BK, and 570 BK/W. The diagram shows the Mass Air Flow (MAF) sensor at connector C130, the EVAP canister purge valve at C129, splices S136, S104, S139, S102, and S101, and connectors C202M/C202F, C185, with off-page references to C107 (page 25-4), C109 (page 25-5), C101M (page 25-2), and C271 (page 25-6). The Powertrain Control Module (PCM) is shown as a solid-state device with numbered pins (24, 51, 76, 77, 103, etc.) grounding through 570 BK/W wires to splice S101 and ground G101; another ground path runs through 57 BK to G100. Explanatory callouts describe the functions of the PCM, MAF sensor, EVAP purge valve, and the relays.

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Frequently asked questions

What does the PCM power relay do on the 1996 5.8L engine?: Per the diagram callout, it directs voltage to the PCM, fuel pump relay, and PCM-related components. It is fed by a 20A fuse (position 9) that is hot at all times, with a start/run feed through the PCM power diode on circuit 175 BK/Y.
What wire feeds the fuel pump relay?: The fuel pump relay is fed through a 20A fuse (position 16) on circuit 37 Y (hot at all times). When energized it outputs +12V on circuits 926 LB/O and 238 DG/Y, directing voltage to the fuel pump.
What connector is the Mass Air Flow (MAF) sensor on and what wires connect to it?: The MAF sensor is at connector C130, with wires including 967 LB/R, 968 T&B, and 361 R power (relay energized).
How is the PCM grounded in this diagram?: PCM pins 24, 51, 76, 77 and 103 use 570 BK/W wires that join at splice S101 and go to ground G101; a 57 BK circuit runs to ground G100.
What does the EVAP canister purge valve do according to this diagram?: It allows gasoline vapors into the engine to be burned; a charcoal-filled canister collects and stores vapors from the fuel tank. It connects through C129 on circuit 191 LG/BK.