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1986 Ford Bronco EFI 5.0L Electronic Engine Control Wiring Diagram (Page 60)

Wiring diagram for the EFI 5.0L electronic engine control showing ECA, emissions solenoids, sensors, and numbered circuits.

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This is page 60 of a Ford electrical/vacuum troubleshooting manual (EVTM) showing the Electronic Engine Control wiring diagram for the EFI 5.0L engine. It traces power from the ignition switch (circuit 20 W/LB via Fuse Link N, 18GA red) and the motor starter relay (circuit 301 R, then Fuse Link Z, 20GA blue) through splice S172 to the EEC Power Relay and out on circuit 361 R to the emissions solenoids: EGR Control Solenoid (EGRC, 362 Y), EGR Vent Solenoid (EGRV, 360 DG), Thermactor Air Bypass Solenoid (TAB, 190 W/R), and Thermactor Air Diverter Solenoid (TAD, 200 W/BK). These feed Electronic Control Assembly (ECA) pins 52, 33, 51, and 11. Lower ECA pins connect to the Inferred Mileage Sensor (IMS) on 223 T/LG, the Exhaust Gas Oxygen Sensor (EGO) via connector C160 on 94 DG/P, a 22K resistor on 11 DG/Y (pin 4), and the ignition module via 349 DB, 324 Y/LG, and 57 BK (pages 29/30). Grounds run through splices S171, S180, connectors C101, C170, C787, to grounds G208 and G710 (page 10). Page references also cover the fuel pump (page 103) and tachometer (page 95). Wire gauge, colors, circuit numbers, and pin assignments are all identified.

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Frequently asked questions

What ECA pins do the emissions solenoids connect to on the EFI 5.0L?
The EGR Control Solenoid (EGRC) connects to pin 52 via circuit 362 Y, the EGR Vent Solenoid (EGRV) to pin 33 via 360 DG, the Thermactor Air Bypass Solenoid (TAB) to pin 51 via 190 W/R, and the Thermactor Air Diverter Solenoid (TAD) to pin 11 via 200 W/BK.
What fuse links protect the EEC circuit on this diagram?
Fuse Link N (18GA red) on circuit 20 W/LB from the ignition switch, and Fuse Link Z (20GA blue) on circuit 301 R from the motor starter relay, feeding splice S172.
What wire color and circuit feeds the Exhaust Gas Oxygen (EGO) sensor?
Circuit 94 DG/P (dark green/purple) runs from ECA pin 29 through connector C160 to the EGO sensor, with a shielded drain wire (circuits 89/0) to pin 49.
Where do the EEC grounds go on this diagram?
Ground circuit 57 BK runs from ECA pins 20 and 16 through splice S180 and connector C787 to grounds G710 and G208; circuit 60 BK/LG grounds pass through splice S171 and connector C101 to battery ground (see grounds page 10).
What resistor is shown connected to ECA pin 4?
A 22K resistor is wired in circuit 11 DG/Y (dark green/yellow) at ECA pin 4.

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