I searched and read for quite some time looking for resistor box installation instructions for my EJ8 that wouldnít require modification of the OEM wiring harness. I read that an OBD1 distributor harness would plug into the dead end harness, but soon found that this was not true because my dead end harness has 14 wires (14p), where the distributor harness that I had collected had only 8 wires (8p). Failing to find the information I needed here, I decided to create my first write-up.
Caution: Disconnect battery before doing anything!
We first must understand the function of the dead end plug. From what I understand, the dead end harness and plug work as a junction to provide power to various things while still leaving the option to add resistance if need be. Here is a photo of plug that goes into the dead end harness:
As you can see, the plug doesnít connect all the wires together as does the 8p plug. The only instructions I found here said to find the 4 injector wires, connect those to the resistor box, and then connect all the remaining wires to the power wire for the resistor box. This WILL NOT work for the 14p dead end harness.
To completely avoid modifying the stock harness (including re-pin), I knew I would have to find a 14p harness that would fit into the dead end harness. Being that I have an EJ8 chassis, the engine harness is one piece, so I used my stock harness with my B18B engine swap. This left me with the extra B18 harness. I almost immediately found the plug I needed on one end of the B18 harness. There was a white plastic piece that I removed with needle nose pliers from inside the plug to make sure it would fit properly. I donít have a picture of the engine harness it came from or the white piece I removed, but here are a couple pictures of the soon to be resistor box harness and the plug I removed from the dead end harness together:
If you are able to get a 14p harness like I did, make sure to cut as far down as possible to avoid needing to extend wires. If you are unable to get a 14p harness and will not be making a plug and play resistor box, then the instructions will be very similar, but look at the end of this write-up for hard wiring the resistor box.
After removing the dead end plug, take the new 14p resistor box harness and plug it into the dead end harness (make sure the battery is disconnected). Now strip ends of the 14 wires for testing as well as soldering a little later (DO NOT BE AFRAID TO SOLDER, IT IS VERY SIMPLE). To find the injector wires, use a multimeter and check for continuity between the wires from the new harness and the injector clip terminals. Testing for continuity basically means to make sure one end of the wire is connected to the other and is able to conduct electricity. To do this, set the multimeter to check for continuity, which should be next to ohms. Next, look for the common color wire between all the injector clips. In my case it was yellow with a black line. To check for continuity, place one of the multimeter leads (doesnít matter which one) on the common color injector terminal, and touch the other to each of the 14 wires individually until the meter shows continuity. Continue this process for all 4 injector clips and be sure to mark the wires as you find them. To speed up this process, you may want to try the four that I found first. Here is a photo of what I discovered:
The wires were all in the second row for mine and it is very likely that yours are the same, but I cannot say for certain, so you must test for continuity.
After locating the 4 injector wires, unplug the new harness and get the resistor box to begin soldering. Here is a picture of a resistor box (which can be found at almost any junkyard or on eBay):
I went to the junkyard for mine and made sure to get one with a complete plug and some length of wire left on it. This way I will be able to unplug my complete harness at any time, but leave the resistor box in place. Instructions are the same whether your resistor box has the plug or not.
The resistor box should have at least 4 common color wires coming out of it and one different color wire. I have heard of injector boxes having more than 4 common color wires, but only 4 will be used here. Solder the 4 injector wires you found on the new harness to the 4 common color wires on the resistor box and seal with heat shrink tubing (this is not required, but I believe it is the most reliable method of joining wires).
Now, recalling that the dead end plug only connected 7 wires at a time, find the other 3 wires that were connected by the dead end plug (besides the 4 injector wires), and solder those together with the different color resistor box wire as seen here:
After sealing with heat shrink, take the remaining 7 wires and solder them together (they will not be connected to anything but each other):
Even after using heat shrink tubing, I still taped everything to be extra safe. I donít need injectors failing.
Finally, cover the harness with loom, zip-tie a few spots, and tape the ends. I chose to use ricey gray loom, with extra-ricey blue tape, but thatís the way I like it, so thatís the way I do it.
Hard Wiring the Resistor Box
I have not done this, but I would recommend removing your intake manifold for better access to the dead end harness. The process for finding the injector wires is the same, but rather than using an additional harness, the testing would be done using the female terminals on the dead end harness. Once you find which group of 7 wires the injectors are grouped with, pull all 7 of those pins from the plug, and replace the original dead end plug to keep the other 7 wires connected. Then, cut the pins off of the 7 wires that you removed and proceed with the instructions ignoring any reference to the other 7 wires.
Summary photo (for reference)
For the physical installation of the resistor box, I chose to relocate my harnesses on the driver side near the firewall to beneath the brake booster. Then, I moved the clutch fluid reservoir closer to the fender, and mounted the resistor box in its place. Here is how it looks installed:
Well, apparently I canít wait for the fall semester of school to start because I am creating homework on my own
. Hopefully this will at least help some people because I know when I looked at where my dead end harness was, I considered selling my injectors and getting some saturated ones. Now I can run either and also be prepared for much larger injectors. From what Iíve seen, 750cc is about as big as they get for saturated injectors.
Like previously stated, this is my first write-up, so it may have turned out very long, but I donít think I included very much useless information. If you have suggestions on how I might improve this write-up, feel free to post here. Good luck!
Modified by DOWNwithHT at 6:43 PM 8/17/2007