I have a high milage 87 TII that needed a new passenger side wiring harness. I aquired one that i was told came off a turboII. It appeared to be identical to what was left of the old one. After installing it i find that this odd looking device on the wheel well that has a large plug on it. I missed it when comparing them some how, i think i might have got a n/a harness. I'v read some where that the solenoid resistor adjusts fuel pump voltage for gas milage or something.
My question is, how important is, and can I rig it up to work some how. I really don't want to try and get another harness, let alone change it again.

 

This would be the perfect time to do the fuel pump rewire mod to install the fuel pump resistor back near the pump.

Pick up main relay power at the fuse panel, the ground signal at the ECU pin 3D, & the circuit opening relay under the dash.

 

That sounds more like the solenoid resistor for your fuel injectors. I believe that is a 6-prong connector with 5 wires (recalling from memory). The connector is located low, near the front of the passenger side strut tower, and the output goes to the fuel injector connectors.


Edit: On second thought, it could be for either the fuel pump or the injectors. I made my comment based on your having an '87, and possibly a harness from a later model. Again, I'm recalling from memory, but the FI resistor is located near the strut tower, and the pump resistor is farther forward.

 

Good point from "buttsjim"
I forgot the S4 turbo's injector resistor pack is under there also.

 

The Fuel Pump Relay and Resistor are NOT a part of the EMISSIONS harness. It is a part of the FRONT harness.

What was described is the Solenoid Resistor meant for low impedence cars. It's a part of the EMISSIONS harness. So the fellow has a high impedence car since his original harness didn't have one. If your going to use the harness with the Solenoid Resistor, then you need to disconnect the Soleniod Resistor from it and put it on the shelf. Then jumper all FIVE of the wires in the harness connector together. Now the harness will be fit for a high impedence injector car.