last time the donor car was being made non-functional, and this week I took my daily driver and made it useless too.

With my wife and kids all out of town, I had her car for a week and some free evenings. The goal is to get the complete underdash wiring harness swapped from the EX civic into the VX civic so that cruise control, A/C, power windows/locks/mirrors will all work.

I HATE HATE HATE wiring. Hate it. It’s tedious. And this older 5th gen civic is a worse than the 6th gen I did this to previously. Older tech means more relays and larger electronics. And slightly worse design means a larger overall harness.

We kick things off with the easy part, strip the various extras from the dash; gauge cluster, radio, etc.


If you recall when I first got the red car, it was DEEP with dog hair, behind the dash was no exception

ok, then we take out the dash (which has it’s own small harness)  and are left with the larger harness, and all the HVAC


see that piece, that’s where I need to put in the A/C component


which I will be stealing from the black donor car, see this earlier image for that when it was still in place in the donor

ok, so dash out, I swapped over the small harness held within. This gave me the wiring/connections for the a/c on-off, for cruise control on-off, and for power mirror adjustment.


There’s ALWAYS some garbage stereo install crap.


This piece of nonsense is responsible for the random (based on bumps and motion) speaker function. And people, when will we learn, are large thick wire for the speakers connected to a teeny tiny widdle wire with twist nuts ain’t gonna make for some awesome sound.

Then, back to the black car to finally snag it’s main harness. which is a MONSTER of a thing. On later models it is in several smaller pieces, with large connectors at the firewall. This however goes from the horn (inside passenger front bumper), includes headlight, snakes along the passenger side of the engine bay to a fuse box, then through the firewall, branches off into the passenger door, then behind all the HVAC gear from passenger to driver side, then along drivers side to rear seat, across to fuel pump, across to passenger door sensor. 

my main concern was that I’d have to remove the heater box, which would mean draining the engine coolant, which I wanted to avoid (at least on the red car) because I want to be driving it again by monday, and will have to wait for another wife/kid free week to do the engine swap.


FORTUNATELY the harness goes under the box, not behind it as I first assumed (it goes behind all the other HVAC components that were easier/necessary to remove.

ok, last place it was stuck is over the pedals, under the steering column, and behind thick sound deadening.


after much cursing, and some failed attempting research (“ya brah, I just dont have power windows in my engine swapped car” seemed to be the general online consensus) I found it was bolted in three places where it passed over the pedals. Some judicious slicing of the sound deadening and...


HAZAH! she’s out.

Bottom left is connection to brake lights etc, connects at the rear seats
Bottom middle is connection to fuel pump, then slightly above that is seatbelt sensor, handbrake sensors.
Top left is the fuse box and connection through firewall to the main engine harness, and a branch into the door.
Odd little plastic bridge goes over pedals under steering column that had three bolts.
Then a long thick snake under/behind HVAC over to passenger footwell
Top right is connection to ECU, branch into door, passthrough firewall into engine bay... then connecting to engine bay fuse box, snaking to the very front right for headlights and horn.

Still to come this week is removing the main harness from the red car, which should be easier with experience from the black.


And at that point I will no longer be wrecking things, it’ll be time to reverse the whole procedure and put the desired harnesses in the desired cars.

Exhausting. This is probably... 6-8 hours or work so far.