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

Per the diagram callout, the PCM power relay directs voltage to the PCM, the fuel pump relay, and PCM related components.

What fuses power the engine controls circuit?

Three 20A fuses in the engine compartment fuse box: one hot in Start or Run (feeding the PCM power diode via circuit 16 R/LG) and two hot at all times feeding the PCM power relay and fuel pump relay (circuit 37 Y).

What wire circuit goes to the inertia fuel shutoff switch?

Circuit 238 DG/Y (dark green/yellow) from the fuel pump relay runs through connectors C202M/C202F to the inertia fuel shutoff, shown on page 25-6.

How is the PCM grounded?

Circuit 57 BK goes to grounds G100 and G104 (see Grounds pages 10-1 and 10-2), and circuit 570 BK/W goes through splice S106 to ground G101.

Which circuits connect the PCM to the Data Link Connector (DLC)?

Circuit 926 LB/O (via C138F/S139), and circuits 209 W/P, 348 T/O, and 915 PK/LB at the bottom of the PCM through connectors C199F and C138F.

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1995 Ford Bronco 5.8L Engine Controls Wiring Diagram - PCM & Fuel Pump Relay 25-1

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

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Wiring diagram showing 5.8L engine control power distribution, PCM and fuel pump relays, and data link connector circuits.

AI caption February 2011 · Photo 463 of 1799

This document is page 25-1 of a Ford factory-style wiring diagram set covering the Engine Controls circuit for the 5.8L engine (part of a 1995 Bronco wiring diagram album). It shows power distribution from the engine compartment fuse box — one 20A fuse hot in Start or Run and two 20A fuses hot at all times — feeding the PCM power diode, the PCM power relay, and the fuel pump relay. Callouts explain that the PCM power relay directs voltage to the PCM, fuel pump relay, and PCM-related components, while the fuel pump relay directs voltage to the fuel pump. The Powertrain Control Module (PCM, solid state) is shown with its power feeds (circuit 361 R, 37 Y), grounds (57 BK to G100/G104, 570 BK/W to G101), and connections to the Data Link Connector (DLC) via circuits 926 LB/O, 209 W/P, 348 T/O, and 915 PK/LB. Circuit 238 DG/Y routes through connectors C202M/C202F to the inertia fuel shutoff on page 25-6. Cross-references point to Power Distribution page 13-5, E4OD Transmission page 30-2, Grounds pages 10-1 and 10-2, and continuation on page 25-2. Wire gauge/circuit numbers and color codes are labeled throughout.

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Frequently asked questions

What does the PCM power relay do on the 5.8L engine controls circuit?: Per the diagram callout, the PCM power relay directs voltage to the PCM, the fuel pump relay, and PCM related components.
What fuses power the engine controls circuit?: Three 20A fuses in the engine compartment fuse box: one hot in Start or Run (feeding the PCM power diode via circuit 16 R/LG) and two hot at all times feeding the PCM power relay and fuel pump relay (circuit 37 Y).
What wire circuit goes to the inertia fuel shutoff switch?: Circuit 238 DG/Y (dark green/yellow) from the fuel pump relay runs through connectors C202M/C202F to the inertia fuel shutoff, shown on page 25-6.
How is the PCM grounded?: Circuit 57 BK goes to grounds G100 and G104 (see Grounds pages 10-1 and 10-2), and circuit 570 BK/W goes through splice S106 to ground G101.
Which circuits connect the PCM to the Data Link Connector (DLC)?: Circuit 926 LB/O (via C138F/S139), and circuits 209 W/P, 348 T/O, and 915 PK/LB at the bottom of the PCM through connectors C199F and C138F.