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Ford Bronco 5.8L California Engine Controls Wiring Diagram - MIL & O2 Sensor 25-11

Wiring diagram of California 5.8L engine controls showing intake air temp sensor and RH heated oxygen sensor circuits to the PCM.

AI caption · Photo 472 of 1799

This is page 25-11 of a Ford factory wiring diagram set covering Engine Controls for the 5.8L (California emissions) engine. It shows the circuits for the Malfunction Indicator Lamp (MIL) and the LH Heated Oxygen Sensor (HO2S) as they connect to the Powertrain Control Module (PCM). The MIL circuit is fed from fuse 17 (10A) in the fuse panel (hot in start or run), through wire 640 R/Y, splice S215, connector C250 to the instrument cluster MIL, then via wire 658 PK/LG through connectors C202F/C202M and the Data Link Connector (DLC, C198F) to PCM pin 17. The HO2S heater is powered by fuse E (15A) in the engine compartment fuse box (hot in run) through wire 298 P/O and splice S134; the sensor signal runs on wire 94 R/BK through C110F/C110M to PCM pin 43, and its ground is wire 57 BK through S168 to ground G100. Wire 359 GY/R connects from C103 (page 25-10) and branches as 359 GN/R to the E4OD transmission (page 30-1). Notes explain that the MIL lights with ignition ON before cranking and that the oxygen sensor provides a voltage related to exhaust oxygen content for air/fuel regulation. Cross-references include pages 13-3, 13-4, 13-11, 10-3, 30-1, 54-3, and 60-3.

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Frequently asked questions

Which fuse powers the LH heated oxygen sensor on the 5.8L California engine?
Fuse E, a 15A fuse in the engine compartment fuse box (hot in run), feeds the LH HO2S via wire 298 P/O through splice S134.
What wire color is the Malfunction Indicator Lamp (MIL) circuit?
The MIL is fed by wire 640 R/Y from fuse 17 (10A) in the fuse panel, and its output side is wire 658 PK/LG running through C202F/C202M and the Data Link Connector (C198F) to PCM pin 17.
When does the MIL (check engine light) illuminate according to this diagram?
The indicator lights with the ignition switch in the ON position prior to cranking and goes off when the engine starts. If a fault develops in the engine control system, the PCM will turn on the indicator.
What does the LH heated oxygen sensor do?
Per the diagram note, it provides a voltage related to the oxygen content of exhaust gases to the PCM for regulating air/fuel ratio. Its signal is wire 94 R/BK to PCM pin 43, and it grounds through wire 57 BK to G100.
Which connectors and splices are shown in the O2 sensor circuit?
Connectors C1028F/C1028M at the sensor, C110F/C110M in the signal wire, splices S134 (power) and S168 (ground), and ground G100 (see Grounds, page 10-3).

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