If you're wondering how to run wiring through the firewall, and have it look like it was installed by the factory, then you've come to the right thread.
There are two factory grommets that pass through the firewall. One on the passenger side and one on the driver's side. To access them, you need to remove the upper strut tower brace. This isn't as easy as it should be.
Passenger Side:
![295234]( "295234")
Driver Side:
![295235]( "295235")
The passenger side is really easy to access from both sides. You need to remove the lower passenger dash cover then reach up to access the grommet from the inside. Removing the glove box may also help here. This is recommended if you don't want to hassle with what I will describe for the driver's side.
Some installers may choose to just cut the nipple off the driver’s side boot and use that as a power wire pass-thru. This requires slicing the boot on the inside to let the wiring pass through the grommet but outside the factory wiring. This is the fastest method but the dealer will easily see what you’ve done and may argue with warranty claims.
The wiring for the driver's side is hidden and routed through plastic channels. The following took me 2 hours to complete. If you want to follow the factory route like I did, you will next remove the battery from the car (ground terminal, positive terminal, then battery hold-down bolt/bracket). Now you have this view:
![295236]( "295236")
And the factory wiring takes a route that goes low then comes back up as shown here:
190606L
![295237]( "295237")
Removing the plastic cover (if you choose to follow the factory path the entire route) is a hassle. It would be easier with the battery tray removed but that is also a hassle. I left the tray in, removed the ground and disconnected the brake booster connector, then opened the plastic cover which allowed me to more easily access the factory wiring loom.
The wiring loom is electrical taped to the rubber boot. Running through the boot requires you remove the tape, carefully. Do not damage or cut factory wiring doing this. You have to remove the tape on both sides. The inside is another hassle because it is behind the parking brake. I removed the parking brake which is also a hassle because of where the bolts are, just a PITA, and there are three of them. Once the parking brake assembly is unbolted, you can swing it out of the way like so:
193932
![295238]( "295238")
And now you can see the inside grommet:
193921
![295239]( "295239")
Once you have the tape removed from both sides you can feed your power wire through the grommet. I recommend some Vaseline on the power wire so it slides through with less friction. When you’ve gotten to this point, the worst is over. This is what it will look like before you start recovering wiring:
200715
![295240]( "295240")
200827
![295241]( "295241")
Now you can take electrical tape (I prefer 3M Super 33+ or Super 88) and recover the wiring bundle and rubber boot on each side. I also use black split loom to over wiring so it looks factory. The inside will look like nothing happened when you are done:
205405
![295242]( "295242")
I need a second post to finish the images.
There are two factory grommets that pass through the firewall. One on the passenger side and one on the driver's side. To access them, you need to remove the upper strut tower brace. This isn't as easy as it should be.
- Remove the two windshield wipers. Note their current position (masking tape on the windshield helps) There is a clip at the pivot point that pops off and reveals a nut. Remove the nut and lift the wiper assembly off the spline.
- Remove two plastic clips at the far left and right extents of the plastic cowl cover (it hides bolts for the strut tower brace).
- Remove the two nuts on each strut tower that hold the brace on.
- Lift the cowl cover and remove the smaller nuts that hold the strut tower brace down.
- Remove the plastic wire clip that is connected to the strut tower brace.
- Remove the strut tower brace from the car (taking care to not scratch the car or damage wiring).
Passenger Side:
Driver Side:
The passenger side is really easy to access from both sides. You need to remove the lower passenger dash cover then reach up to access the grommet from the inside. Removing the glove box may also help here. This is recommended if you don't want to hassle with what I will describe for the driver's side.
Some installers may choose to just cut the nipple off the driver’s side boot and use that as a power wire pass-thru. This requires slicing the boot on the inside to let the wiring pass through the grommet but outside the factory wiring. This is the fastest method but the dealer will easily see what you’ve done and may argue with warranty claims.
The wiring for the driver's side is hidden and routed through plastic channels. The following took me 2 hours to complete. If you want to follow the factory route like I did, you will next remove the battery from the car (ground terminal, positive terminal, then battery hold-down bolt/bracket). Now you have this view:
And the factory wiring takes a route that goes low then comes back up as shown here:
190606L
Removing the plastic cover (if you choose to follow the factory path the entire route) is a hassle. It would be easier with the battery tray removed but that is also a hassle. I left the tray in, removed the ground and disconnected the brake booster connector, then opened the plastic cover which allowed me to more easily access the factory wiring loom.
The wiring loom is electrical taped to the rubber boot. Running through the boot requires you remove the tape, carefully. Do not damage or cut factory wiring doing this. You have to remove the tape on both sides. The inside is another hassle because it is behind the parking brake. I removed the parking brake which is also a hassle because of where the bolts are, just a PITA, and there are three of them. Once the parking brake assembly is unbolted, you can swing it out of the way like so:
193932
And now you can see the inside grommet:
193921
Once you have the tape removed from both sides you can feed your power wire through the grommet. I recommend some Vaseline on the power wire so it slides through with less friction. When you’ve gotten to this point, the worst is over. This is what it will look like before you start recovering wiring:
200715
200827
Now you can take electrical tape (I prefer 3M Super 33+ or Super 88) and recover the wiring bundle and rubber boot on each side. I also use black split loom to over wiring so it looks factory. The inside will look like nothing happened when you are done:
205405
I need a second post to finish the images.
