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Hello, I’m working on a project truck with my son. It’s a 94 f150. Stock motor was the ole 300 but he wanted to swap for a 351. I was able to get a wiring harness from guy online and now as I’m putting it back together I’m noticing there is no plug in on the passenger side of the harness for the TPS or IAC valve. Those plugs should be on the passenger side of the harness, correct?? I have two plugs (besides the fuel injector plugs) and one goes to the ECT sensor…. See pic. Am I correct? Are those plugs in another location? I was told this harness was from a 95 351w Two plugs on passenger side of harness
There are several ways a '94 F150 4.9L can be built; and several DIFFERENT ways for a '95 5.8L to be wired. So you should NOT plug that wiring together with a battery connected until you have exhaustively investigated the exact routing of each circuit to make sure they're either 1) entirely compatible, or 2) properly modified to work together. If not, you could set the truck on fire when the battery is connected & everything is plugged in. The connectors WILL fit together, but that does NOT mean they work together. You & he would be MUCH better-off simply maintaining/repairing the original engine with its original wiring. A 5.8L makes slightly more torque than a 4.9L, but at a MUCH-higher RPM (less useful unless he's drag-racing), and the engine is MUCH heavier (meaning some of that torque is wasted pushing the extra weight). My 4.9L F150 is very nimble & peppy.
The best way to ID electrical connectors or connected components is to ID the wire colors and then look them up on this page & the NEXT few:
For example, in your first pic: LG/R in that chart can be (among other things listed) the stoplamp (BOO) switch feed, but that wouldn't be on the engine. It can be an alternator wire, but you'll find that LG/R wire in the alternator harness behind the battery. So it has to be the ECT, which uses that style of connector and also has a Gy/R (SIGRET) wire as confirmed in this diagram:
I really appreciate your response and time. Unfortunately we are way past keeping the 4.9 as that’s gone and the Windsor has been rebuilt and is sitting in the frame. I’m just trying to determine if the TPS and IAC valve plugs should be on the passenger side of the harness or do they come from somewhere else? There aren’t a ton of things that the harness needs to plug in to as I have deleted the AC,smog and EGR as part of the build. I purchased a new IAC from local parts store and there is no connector in the harness with that type of plug.
Wiring harness help
