What does the PCM power relay do?

Per the callout, it directs voltage and current to the PCM and PCM system related components. It is located in the engine compartment fuse box and outputs on circuits 701 W/R and 702 R/BK.

What wire color and circuit feeds the fuel pump relay and distributor?

Circuit 702 R/BK from the PCM power relay splits at splice S189 to the fuel pump relay (page 25-6), splice S191 (page 25-2), connector C180 (page 25-3), and the distributor at C134 (page 21-4).

How does the FPRC solenoid valve work according to this diagram?

It controls fuel pressure at the injectors, varying pressure by a manifold vacuum signal: high manifold vacuum (idle) gives low fuel pressure; low manifold vacuum (hard acceleration) gives high fuel pressure. It connects to the PCM at connector C246 pin 37 via circuit 772 GN/BK.

Where does the PCM ground circuit go?

Circuit 50 BK runs through splice S106 (see Grounds, page 10-6) to ground point G103.

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1993-1994 Ford Probe PCM Power & Ground Wiring Diagram - ECU Page 1

Ford EVTM wiring diagram for power distribution, IMRC solenoid and powertrain control module

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Ford wiring diagram showing power distribution to the PCM, IMRC solenoid valve and automatic transaxle with color-coded wires and connectors.

AI caption July 2012 · Photo 413 of 676

This is a scanned factory-style wiring diagram page covering the power supply and ground circuits for the Powertrain Control Module (PCM) system of a Ford Probe. It shows three power sources: the 15A ENGINE fuse in the interior fuse panel (hot in start or run, page 13-7), the 30A F/P INJ fuse in the engine compartment fuse box (hot at all times, page 13-1), and the 15A ROOM fuse in the interior fuse panel (hot at all times, page 13-6). The ENGINE fuse feeds the PCM power relay coil via circuit 40 BK/W, while the F/P INJ fuse feeds the relay contacts via circuit 9 W/GN. The relay output on circuit 702 R/BK splits at splice S189 to the distributor (C134), the fuel pump relay, splice S191, connector C180, and the FPRC solenoid valve (C187), which feeds PCM pin 37 via 772 GN/BK. The ROOM fuse supplies keep-alive power on circuit 84 BL/R to PCM connector C248 pin 1 and to the 4EAT transaxle (automatic only, page 29-4). Ground is via circuit 50 BK through splice S106 to ground G103. Explanatory callouts describe the PCM power relay, distributor voltage function, and FPRC solenoid fuel-pressure regulation behavior.

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Frequently asked questions

Which fuses power the PCM system on this diagram?: Three fuses: the 15A ENGINE fuse in the interior fuse panel (hot in start or run, page 13-7), the 30A F/P INJ fuse in the engine compartment fuse box (hot at all times, page 13-1), and the 15A ROOM fuse in the interior fuse panel (hot at all times, page 13-6).
What does the PCM power relay do?: Per the callout, it directs voltage and current to the PCM and PCM system related components. It is located in the engine compartment fuse box and outputs on circuits 701 W/R and 702 R/BK.
What wire color and circuit feeds the fuel pump relay and distributor?: Circuit 702 R/BK from the PCM power relay splits at splice S189 to the fuel pump relay (page 25-6), splice S191 (page 25-2), connector C180 (page 25-3), and the distributor at C134 (page 21-4).
How does the FPRC solenoid valve work according to this diagram?: It controls fuel pressure at the injectors, varying pressure by a manifold vacuum signal: high manifold vacuum (idle) gives low fuel pressure; low manifold vacuum (hard acceleration) gives high fuel pressure. It connects to the PCM at connector C246 pin 37 via circuit 772 GN/BK.
Where does the PCM ground circuit go?: Circuit 50 BK runs through splice S106 (see Grounds, page 10-6) to ground point G103.