Wiring connects on the firewall?

1999 FORD F-250
350,000 MILES • 7.3L • V8 • TURBO • 4WD • AUTOMATIC
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DAVIDBURNETTE
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Looking for a pin diagram explaining what the wires are for on a 99 F250 7.3 diesel. Plug in question is the bottom large grey plug on the drivers side. Plug connects on the firewall and goes out to engine bay.
Mar 21, 2026 at 7:02 PM
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AL514
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Hello, can you count how many wires there are in that connector? There are quite a few bulk multiple junction connectors like that on this truck, I believe I have the correct one here, looks to be about 42 pins. Ill post a couple diagrams of bulk connectors and you let me know which one it is by wire coloring.
Mar 22, 2026 at 11:38 AM
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AL514
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These are a couple bulk connectors, on most lists for harness connectors will give some idea of their location by their number, so C138 and C103 for example, could be towards the front of the vehicle and the higher numbers will be the connectors going further back towards the rear. I will keep looking through the list of connectors in service info as well.
Mar 22, 2026 at 11:48 AM
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AL514
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Service info this old doesnt always show the locations of components or connectors in all cases. But this should help, it looks like from the dash view here, C1049, C1050, or C1051 could be one of the connectors youre trying to ID being in that location, Im pulling up those connectors right now for you.
Mar 22, 2026 at 12:22 PM
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AL514
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These are connectors C1049-1051 and their location in the engine compartment. These 3 connectors go through the firewall at that location and then above the Brake pedal is where they look to come threw.
Mar 22, 2026 at 12:45 PM