Adding extra wires for future proofing electrical upgrades…

e9Leveque

e9Leveque

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Since I pulled my wiring harness from the front of the car into the engine bay in preparation for refresh of bay, I’m wondering about adding some extra wires that go to the fusebox area or beyond for any future upgrades I might do. I already have my battery in the trunk with a distribution block in the old battery location, and have added relays (and their wiring) for stereo/amp, headlights, and rear window motors, etc, but wondering what other upgrades people have done that might be more easily accomplished with wiring already in place rather than having to go add an additional wire to the harness later.
Some options I’ve seen discussed in searching older threads:
1. Heated seats. I added this to my E39 and it’s a game changer for colder days (or even cool spring days) here in Seattle. That was easy, but these seats seem a bit daunting to me and I’m not sure whether it’s worth taking on. This would likely be a wire that I could add just terminating with extra cabling under the driver seat.
2. Map light: my car doesn’t have this, not something I think I would need/want, but it does look like an option on some cars
3. A/C: while I imagine most of this wiring would be within the engine bay, this is an upgrade I’ve considered having our good friend Don do in the future. Any wiring for the controls that should be added now?

Any others? Hopefully this list will serve as a list of possible electrical upgrades for others as well.
 
one map light ideas is to use the e28 / e30 mirror with map lights at the bottom edge. you just have to run power from the dome light to the mirror (a few inches for non-sunroof cars).

i like the heated seat idea, to me its only something to tackle if you reupholster the seats.

i added a power distribution block in the interior of the car, fed directly from the battery to send power to the window motors and anything i do with stereo or possibly heated seats. i think i ran a 10 or 12 gauge wire down the harness.
 
AC wiring:
in the front you have
-the additional fan (which has a direct + from the battery to the relay)
-the pressure switch in the drier
-the compressor

the other wiring is from fuse box to the center console - blower motor, blower switch and temp switch.

There is one wire going from the temp switch to the engine bay.
 
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Dlc said:
AC wiring:
in the front you have
-the additional fan (which has a direct + from the battery to the relay)
-the pressure switch in the drier
-the compressor

the other wiring is from fuse box to the center console - blower switch and temp switch.

There is one wire going from the temp switch to the engine bay.
Click to expand...
Got it - so worth having one heading to rear of console for that.
 
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in the wiring diagram you have
-12 battery
-11 fuse
-10 add'l fan
-9 relay
-8 compressor

in the front

3-7 sit in den center console

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I've installed a couple of additional circuits into my car:

- Seat harness inertial reel (my harnesses contain an inertial reel that will pull you back into the seat when the yaw sensors detect an accident).
- Fuel pump controller for my electric fuel pump.
- Footwell lights on a fade to black timer (this is actually an add-on to the dome light circuit).
- Secondary temperature trigger for the fan in front of the condensor, run off a temp sensor in the lower radiator hose connection independent of whether the a/c is on.

You might also consider a fog light circuit, and a circuit to charge your cell phone.
 
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You don’t need an extra wire in the console for the a/c. If adding a USB like I did in the glovebox don’t run it off the same fuse as the radio.
 
HB Chris said:
You don’t need an extra wire in the console for the a/c. If adding a USB like I did in the glovebox don’t run it off the same fuse as the radio.
Click to expand...
My radio has a USB output off the back of it (Retrosound) but yes, maybe best to just have a separate dedicated circuit. The distribution block I have in the engine bay has a fusebox so I can run things “direct” from battery (which all go through a much larger 100A safety fuse) or I can have items run from block to fuse/relay and then out to rest of car
 
You might want to run a few 00 wires from the trunk to the engine bay for that future Mr. Fusion electric power source :p
 
e9Leveque said:
Touché ! May have to print this as a lark at some point. I also still owe you an assessment of the LED rheostat that we had discussed in the gauge lighting thread. The part arrived but I haven’t had time yet to play with the multimeter.
Click to expand...
Only if you promise to get a photo of it mounted to the trunk lid of your coupe!!
 
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