bigblock wiring

​My notes from the 88 harness.

But now i have a big problem. the bulkhead fitting for the '90 harness has pins in different places. looking at the two, i see 5 pins that are not in the right spot. Comnparing the 89 & 90 harnesses, they are pinned almost identical. (the 89 harness came w/ the motor, but is butchered by previous owner, the 90 harness came with my cab)

This is a huge problem. I need it pinned like the 88, for it to work with the dash harness. I see myself as having three options.
#1, i rewire my 88 chassis harness to plug into the 90 control harness, and then re-pin the bulkhead connector to plug into the 88 dash harness. This seems to be the easier of the two, but now i have a custom harness so if anything happens to it ill be ****ed.

#2, completely rewire the motor harness to plug into the 88 main control harness. This is gonna be a huge project because it will require grafting the 351 harness onto the 460 since the ECM connector is on the 88s engine harness. This will make it kind of like a 88 F350 harness, but is not something i want to do because it will be crazy hard to do.

#3, find a engine harness from a 1988 F350 w/ 460. Somehow i dont see this as very feasible.


My father has the complete Ford wiring diagrams book for a 1990 which he is going to mail to me, so thats half the battle right there.
Here is what i need. I need to know the color code for all the wires that go to the tailgate on a 1988 bronco, so i can eliminate those wires from the bulkhead fitting. Those could very well be the wires that dont match up with the main control harness im using. At this point i dont know what too many of the wires are for, only where they go. I know the parts guys at the local Ford dealer, so im going to see if i can get these diagrams tomorrow.

​Notes on the '90:

​Some interesting info.

Both harnesses have 24 wires. All of the similar pins in the bulkhead connectors go to the same places, and most are the same colors.
The 88 has 7 wires the 90 does NOT have. The pins arent even in the 90's bulkhead connector. I suspect 4 of these are for the tailgate. The other 3 i have no idea, as of yet. Possible they have to do with the dual vs. single fuel pump setup in 88 vs. 90? I dont know yet.

The 90 has ~8 wires that, while they have corresponding pins on the 88's bulkhead connector, they dont go to the chassis in the 88 harness. Tomorrow i need to ohm out these pins on the 88 harness, to see where they go (maybe to the engine or elsewhere? or possible for the dual tank setup the 90 had?)


The wiring for the O2 sensor is different too. Rock Auto lists a different O2 sensor for each year, but the Ford p/ns seem to be the same? Not sure yet. The 88 has a 3-wire O2 sensor, the plug on the 90 harness has 4 wires. I think the difference is that the 90 has a ground wire in the plug, i dont think the 88 did.

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