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Sensor plug diagram thing


I got a 97 Buick century and I just did an engine swap but there are 40 fucking billion of these goddamned plugs and I don’t know where they go
Is there a diagram of where they go and what is it called


I haven’t seen a diagram with all of the connectors, but there are swap guides and other similar stuff on forums out there. Pretty much any W-body 60* 3X00 (3100, 3400, 3500) swap guide will apply your car as far as wiring and sensor location.

I will try to get some pictures of the loom on my Impala tomorrow, as that has a blown 3400 in it. I already have the loom unplugged from everything and numbered, but I’ve been down this road a few times before and know all of the sensors in my head, so I would have to make notation on the pics to be useful to you.


This maybe? Might have schematics in it, as long as the wires are coloured properly.


OK I took a few pics to get you going. Some of the connectors may be slightly different for you, but this is one of those things that seems really daunting at first but isn’t that bad. Once you get a few connectors in place, the stiffness of the wire loom tends to point all of the connectors were they need to go. There are also very few connectors that are the same, whether a different shape or keyed differently, so it’s pretty hard to put the wrong connector in to something.

Intake Air Temperature (IAT) sensor and Mas Air Flow (MAF) sensor.

The unlabeled red connector is for the EVAP solenoid, and the unlabeled black connector between the throttle position sensor (TPS) and the EGR is the Idle Air Control (IAC) solenoid.

This pic gives you an idea of what the labeled connectors look like on the male side.

The two pin connector labeled IGN connects to the Ignition Control Module. The other end of that goes down to the Crankshaft Position Sensor which is located on the rear (firewall) side of the block under the exhaust manifold in the middle. There is also one for the Vehicle Speed Sensor on the passenger side of the transmission; those two are the outliers that you need to get under the car to plug in. There is that one transmission bolt that takes ~2’ of extensions to install, so if you still have the wheel off for that then you should have good access.

The one labeled ALT goes to the alternator. The large purple one I refer to as the BAC (Big Ass Connector) which goes to a small harness for the injectors. I’m not sure when then started using it, as I haven’t torn apart any mid to late 90’s W-body’s, only earlier and later ones. The white 4 pin connector goes to the oxygen sensor. That one might also be a bit different for you.

In my case, the computer is behind the driver’s side headlight, all the wiring runs in front of the engine to the fuse box on the passenger side, and then wraps around the engine towards the back. Your car might be different, as well as the grounds. They tend to put studs with an extra nut in places where grounds go, so hopefully it is easy to figure out where to ground things.

That’s a good chunk of what you need to do. If you end up with any connectors that you can’t find a home for, then try to make note of the number of pins, general shape, and rough location in the engine bay or other connectors on the loom. Pics help too. I know there was one connector for a variable power steering system that was rarely used and I’m not sure when they stopped using that. It’s not uncommon for a few connectors to have nothing to plug in to.