I got my b20 prepped and now I'm ready to throw it into my 90 hatch. When I bought the shell it came with a converted mpfi harness and obd1 ready. I need some help with where each connecter plugs into. Do I need a separate alternator harness? I'm running an obd1 LS alternator. Any help much appreciated.

 

Wow...I'm sorry but I don't have every connector memorized. I will tell you what I know, and give some advice:

1) Mark each sensor with masking tape and write the name on it (while it is still laying there.
2) After you have everything named what you think it is, then post another pic asking for the ones you aren't sure about.
3) Starting with the big giant plug on the top right, that should usually fit the main plug on the passenger strut by the Fusebox under the hood. (I'd flip over the harness on the ground to actually simulate its location in the engine....as it is laid there, it looks mirror opposite??)
4) From there, most proper connections can be determined by where the plug will reach COMFORTABLY.
5) The fuel injectors plugs are the 4 grey plugs with the red wire loom on them.
6) You probably have ONLY 1 plug that will fit AND reach an aluminum box at the corner of driver's firewall and driver's fender. That's the location of the injector resistor box (if equipped).
7) Your last picture shows 1 plug, 2 slide connectors (1 green, 1 yellow), and a single slide connector (it looks white in the picture). The yellow and green slide connector connect to a transmission sensor on the front of the passenger side transmission. The single white connector slides onto the (engine coolant temp??) sensor nearly above the trans connectors but it'll be on the side of the head. The other plug, I can't remember without looking at a honda engine, but probably will only reach one matching plug comfortably in that area.

8) As for the rest....they will usually only fit one plug COMFORTABLY with the engine harness connected as it is so far.

9) The most common mistake in hondas is accidently mixing up the MAP and TPS sensors because the 3prong plugs barely reach the wrong sensor. Use google to find out the proper color of the MAP and the color of the TPS plugs so you don't plug them in "inverted."

10) The second most common mistake is to "invert" 2 plugs near the driver's side of the intake manifold because they will fit and barely reach (if your engine is equipped with the Honda component that I am thinking of). Again, if you have 2 connectors and arent sure, use google to search for "b20 IAT wire color" and "b20 IAB wire color" (if your car has IAB's).

11) Please post another pic after you have flipped that harness over (while out of the car) ANDDDD used masking tape to label and name each plug you have identified. I am probably given you atleast half of them, and the other half usually only reach 1 plug. So please, label what you know and post the pic so we can fill in the blanks.

 

I appreciate it, I will do that.

 

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Ill make it easy on you. Get a new harness. That harness has connectors on it that will not plug into Honda sensors. Some of this are Delphi connectors.
1. Unknown not a Honda connector
2. Starter signal
3. Thermostat ground
4. Tandem (ignore DPFI only)
5. Iat
6. Tps

Your coolant switch (you marked) is actually fan switch (you need to rewire to thermostat housing)

The o2 sensor (you marked) is actually engine coolant temp sensor for the computer

 

Good job on the labeling. The last post has some good info in it (identifying the sensors). I have no idea if you need a new harness, but even if you do need a different harness, you are now ready to identify each plug on it. If you have questions on the new harness, post up pics of it too. btw...your pics can be zoomed out a little more, so we can see the location of the plug on the harness also. The quality pics you are posting will still allow us to see the color of the wires. :D

I think there should be a detailed pic of each honda harness for all cars with the plugs labeled in the stickies section. But of course, I don't have the harnesses laying around, or the time to tackle something like this. If you want to fully label your harness(es) and post pictures for future users, hopefully you will start a trend until a picture of all harnesses is available. :D

 

I was thinking I might need a new harness too. Thanks you guys for your help.