What components ground through G103 on the 5.0L Bronco?

The Electronic Engine Control (EEC) Module (pin 49) and the Heated Exhaust Gas Oxygen (HEGO) Sensor both ground through circuit 89 to ground G103. A third branch at connector C110 is marked (NOT USED).

What is the wire color and circuit number for the G103 ground circuit?

Circuit 89, wire color O (orange), is used for all branches of the G103 ground circuit shown on this page.

What connectors and splices are in the G103 ground path?

The HEGO sensor wire passes through connector C114; all branches join at splice S107; the wire then passes through connector C101 before terminating at ground G103. Connector C110 is shown but marked (NOT USED).

Is C110 used on a Bronco without the E4OD transmission?

No. C110 is labeled (NOT USED), and the diagram notes 'NOT USED ON BRONCO WITHOUT E4OD TRANSMISSION.'

Where can I find the full EEC module and HEGO sensor diagrams referenced here?

Both the EEC Module and the HEGO Sensor diagrams are referenced to page 24-4 of the same manual set.

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1990 Ford Bronco 5.0L Grounds G103 Wiring Diagram - EEC & HEGO Ground Circuit

Grounds wiring diagram G103 for 5.0L showing EEC module and HEGO sensor ground paths through splices

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Grounds diagram (G103, 10-8) for 5.0L showing ground circuit 89 routing from EEC module and HEGO sensor through splices to G103.

AI caption April 2011 · Photo 672 of 1799

This is page 10-8 of a Ford factory wiring diagram set, showing the "GROUNDS (G103)" circuit for the 5.0L engine. The diagram traces the ground path for circuit 89 (orange wire) from three sources: the Electronic Engine Control (EEC) Module pin 49 (referenced to page 24-4), the Heated Exhaust Gas Oxygen (HEGO) Sensor (also page 24-4, through connector C114), and connector C110 which is marked "(NOT USED)". All three legs of wire 89 O join at splice S107. A callout box notes that one branch is "NOT USED ON BRONCO WITHOUT E4OD TRANSMISSION." From splice S107, the single 89 O wire passes through connector C101 and terminates at chassis ground G103. A reader can learn how the EEC module and HEGO sensor share a common engine ground (G103), which connectors (C114, C101, C110) and splice (S107) are in the path, the circuit number and wire color (89, orange), and where to find related diagrams (page 24-4). The page was uploaded as part of a 1990 Ford Bronco documentation album, and the callout referencing the Bronco without E4OD transmission is consistent with that application.

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Frequently asked questions

What components ground through G103 on the 5.0L Bronco?: The Electronic Engine Control (EEC) Module (pin 49) and the Heated Exhaust Gas Oxygen (HEGO) Sensor both ground through circuit 89 to ground G103. A third branch at connector C110 is marked (NOT USED).
What is the wire color and circuit number for the G103 ground circuit?: Circuit 89, wire color O (orange), is used for all branches of the G103 ground circuit shown on this page.
What connectors and splices are in the G103 ground path?: The HEGO sensor wire passes through connector C114; all branches join at splice S107; the wire then passes through connector C101 before terminating at ground G103. Connector C110 is shown but marked (NOT USED).
Is C110 used on a Bronco without the E4OD transmission?: No. C110 is labeled (NOT USED), and the diagram notes 'NOT USED ON BRONCO WITHOUT E4OD TRANSMISSION.'
Where can I find the full EEC module and HEGO sensor diagrams referenced here?: Both the EEC Module and the HEGO Sensor diagrams are referenced to page 24-4 of the same manual set.