October 2003: Wiring Harness Re-Install

If it weren't for guys like Steve Good living in my town, I would be lost on things like this. Steve's experience installing wiring harness is legendary when the topic comes up. He once strung a 67 1600 with a 76 wiring harness in the same weekend. So I take him at his word when he says he'll help me put it all back in.  He didn't let me down!  First, you stretch the two parts out on the floor to get the layout understood.
There are two harnesses. One is pushed from the cabin into the firewall and backwards towards the trunk, the other you feed from the engine compartment back into the cabin. This one below is the cabin to trunk section. It's the longer of the two pieces.
On the cabin side, you lay things in the general area they will be installed.
On the driver's side, the harness runs underneath the seat mounts closest to the door.
They are fed through this hole in the back seat bottom support, and then secured in place to the car using the tabs welded onto the tub.
The harness going to the tail lights and fuel pump are fed through the driver's side access hole to the trunk. Note that the rear door panel is not required to do this, but was being test fit and forget to remove it for this photo shoot.
On the trunk side, you pull this all towards you and prepare to feed it into the locations around the perimeter of the trunk where it was originally stored. It also has tabs to hold it firmly against the car.
Up front by the firewall, we pull the harness through the upper hole in preparation to feed into the large hole in the upper right to connect to the fuse block assembly.
The wires are fed into the big hole and set aside until the next harness assembly is installed.
This new fuse block bottom shows how color coded it is. Fortunately I have another car to compare this to, so it was easy to put the wires in the right places. Arrows show how it fit in this part of the harness.
View showing how the fuse block will look and fit into the body shell on the driver's side fender.
Ok, in the drivers side foot well, the wiring is fit into place. Another reference car is used to pull relays and get actual location of the harness placement. Never underestimate how good a picture is worth in this case.
Another view looking up towards where the heater box goes. Those wires will have a home as I put the heater box back in it's cavity. It's important to note that I used a special high heat tape which is narrow and white to re-wrap the harness this time around. It's much better than friction tape and is made of fiberglass.
On the firewall side, I pull wires through the hole while Steve pushes from the driver's foot well. The arrow indicates the wiring plug for the windshield wiper motor. I also felt it was easier to leave the wrapping on the harness thin in some places so that it would easily travel through the holes. The original harness was so thick it's almost impossible to get it through the holes without the tape coming off. I'll further wrap the wires completely once they are in place.
Feeling pretty good here, the first harness is in place now.
More wires are feed and organized through the seat bracket before final lock down.
Final securing of the harness down to the tub begins. I believe we have done a far superior job than the factory did, judging by the amount of carpet glue and crud removed from the tub originally.
Closer inspection of own it looks. I plan to finish insulating the car with sound deadener now that the wiring is secured.
A view looking at the bundles moving into the rear seat area.
Don't forget the reverse switch wires. This was a tricky one, and also includes setting a new 1/4" rubber grommet into the tub to keep water out. This section will also have a protective sheathing placed over it before installing it onto the transmission.
A view looking towards the fender well for clarity.
In the trunk we have placed wires behind the trunk hinge bracket.
Next up, the E30 battery cable is pulled through the hole. It is the thick cable that will travel to the front of the car to be connected to the original battery cable assembly. This is necessary when you re-locate the battery to the trunk as I have done. Fortunately, this cable also has a second power feed wire that can be used for powering a stereo amp or other type device, or relay for an alarm system without having to tap into the cable itself. The lower arrow points to the hot wire used for the rear window defroster.
Here the power cable is brought over where it will be attached to the battery soon.
The cable follows the same path as the harness. Later I will attach it to the firewall with other parts from the E30 to finish the installation. That will be covered later this month or next.
This cable is also managed under the seat bracket also. Don't forget the Wurth Contact OL solvent!
In some cases, the sheathing the cable had was brittle. This time I was sealing up the wires going to the fuel pump with black heat shrink tubing and a heat gun. Be careful and don't melt in any wires in the process!
Ok, the firewall side harness comes next. Here I am pulling the wires through the firewall.
There was several wires that needed to be pulled through. These wires go to things on the gauges such as the tach and water temperature.
Back up front, we need to shoe-horn the rest of the fuse block wires into that small hole with the previous ones.
By shoe horn, I mean shoe horn! here you see it's important to make the wires in the hole as narrow as possible. Take your time, these are also fragile plastic ends.
Finally all in. This is trial and error to get them all in there. Spray Wurth Contact OL solvent in these ends before you install them to keep any corrosion off.
Ok, on the fender, the master ground cable goes here. Sand off the paint with a Dremel tool and make sure all surfaces are clean on the copper cable end also. A 10 mm bolt with a washer is key to good ground here.
Ok, it's not the wiring harness, but the return fuel line for the TII. It and the tank vapor canister tubes follow the same path for 80% of the layout. The fuel return line goes in the lower hole, the vapor lines go into the hole on top of the rear fender well.
On the passenger foot well, the location of the plastic line requires a new rubber grommet installed in the firewall. Push the tube through, later it will be attached to the engine.
A view of the area adjacent to the brake fluid reservoir. Previously I installed it, along with the voltage regulator with new bolts or screws. Note the brown/white wiring harness is clearly marked for the future. The other arrow shows a rubber gasket which carries the harness wires to the headlights.
A view showing the two lines going to the fuse block. The small plug adjacent to it runs an original engine diagnostic tool. It is great for remote starting or measuring RPM if you have a tool such as the 2002Tuner.
Looking back at the whole setup after I have secured it for now. Arrows point to the original hot lead (pink) going to the battery, and the lower wiring bundle that goes to the fuel injection and the starter.
Firewall view. This is pretty hooked up now. Arrows point to the return fuel line and fuel vapor line.
View of the core support wires, which run behind the radiator. These use specially designed BMW wiring harness nylon straps which anchor it in place (arrows). You can also see the right side headlight wires going into the core support.
A view under the dash shows things are attached to relays and looking quite tidy. I'm totally happy with the way it has turned out - better than I anticipated, but I still have a few new plastic ends to put on which are very cracked. Wurth can provide the period correct wire spade lug ends with insulated covers.
A view showing the fuel lines and vapor lines that go back to the trunk. This is the passenger side foot well.
Tracing back to the passenger side wheel well behind the back seat.
Just for the photo shoot, I've placed the tank temporarily in the car. You can see how the wiring harness is secured to the body and the far black lines power the electronic fuel pump under the car. Actually the silver tank looks pretty cool, but I'm sure it will be black when I'm all done screwing it back into the car.
WHEW, lots of photos. But a hard subject to talk about without them. I sure hope this helped you tackle the job yourself. It's easy when you have helpers like Steve who have the experience to make it happen.

Also I rebuilt the wiper motor bearings, bushings and the brackets holding the wiper arm assembly under then hood. This is no small chore, however I left my camera home and didn't take any pics. A future topic for sure... I used Mobil 1 synthetic assembly lube wherever moving parts were previously lubed with that type of grease. I still need more parts for the ends of the wiper arms to finish up.

The firewall blanket was installed. These are still available, but you have to use an Exacto knife to cut out some areas that are filled in from the injection molding process.
After the blanket goes in, the bracket that holds the TII brake booster was installed.
The brake fluid reservoir has two sharp screws that are exposed. There are two parts which are plastic tips which cover these up. Chances are yours are missing.
A view showing these areas prior to installation of the harness.




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