I'm trying to feed wires from the battery though the firewall to the center console for a Ham radio. How is that normally done? Do I have to take off the front right fender? I can't see any entry point on the firewall under the dash.

 

you don't say what model car you have, so I'm kinda wildcarding my response

I haven't done my 745 yet, but on my 850 and our 240, there was a rubber plug somewhere on the firewall not far from the steering column (I think its to the left and somewhat above the steering column) that had like nipples you could snip to create wire ports. this was there specifically for add on auxilliary wiring. actually, after I wired my stereo amp power, and trailer brake controller on the 850, I discovered that Volvo had already put some wires in specifically for those purposes, hah!

the 240 I did so long ago I don't recall if the rubber plug had nipples or not. I may have just put a hole in the plug, run my wires through, then goobered it up with some RTV (silicone rubber sealant) to keep the weather and fumes out.

you definately want to do it on the left side, away from the exhaust system. anyways,the battery is on the left on most of these cars.

 

OOPs Goofed. It is a 1992 240 wagon!

 

k, let me go out and look at where my trailer power wiring goes through the firewall on our 87 240 sedan... ahhhh. ok. ummmm. the drivers side wheel well, I snaked the wire under the topmost piece right along the outside edge of the engine compartment, and where the wheel well joins the firewall, there's an opening, and you can see a couple existing cables that come across the top of the brake master cylinder against the firewall, then duck into that opening, and through a rubber plug. I think I found that under teh dash and poked my wire out, then pulled it from the compartment side and fed it through that channel between the top plate which supports the strut tower, and the actual wheel well, its right along the outside edge of the compartment all the way to the battery. in my case, its just a big fat red "+" power wire, using aircraft grade fuel-proof and high temp insulation (love that silver tinned aircraft wire, it solders so nicely).

btw, if you need to run stuff to the back... In the past I've always run it under the driver's door sill, and behind the carpet, but my Volvo parts CD suggests you should instead run stuff along the base of the transmission hump on the passenger side, under the carpet, then behind the back seat zig over to the right side, and over the right wheel well under the plastic. I dunno, once its there, I'm sure its great, but getting there would probably require pulling the center console and the passenger seat, me thinks, big job.

 

Well, I solved my problem. I pulled a plug high on the firewall. I ran a fish tape down and after jiggling it around, I put more and more into it and realized it had to be going into the rocker panel as there was no place else. It didn't pop out underneath or in the cabin.



I popped this plug off [below] and felt around and found my fish tape. No rust in there, which was nice to know also.



Success. I pulled the wire through, but the long path means I have to lengthen the wires.

 

k, here's where I ran mine.





the plug I used is behind that hole, and has those hoses/wires/whatever that snake around the top of the brake cylinder going through it, I poked my wire through it from the INSIDE, then found it behind that panel and fed it between the strut tower and the wheel well and the fender to the battery. worked great.

any plugs you removed, I hope you poked your wires through small holes in them and replaced them, those plugs keep road crap and fumes out of the passenger area.

 

A fish tape! Props to you. On my car that plug in the rocker is to help keep the water draining area under it from wetting the rug. You may consider plugging it back up around the wire there. But it might not be a problem as well. I just figured I'd throw that one out there.

 

I tried that area. I actually found an empty wire loom and tried my fish tape down that. I could not see it come through the firewall, and looking on the inside, did not see anyplace where wires came through. I did spot the cable hood release, but there was no space unless I drilled a hole.

I cut a slit in both rubber and plastic grommets. It is a tight fit but dam of caulk would not hurt also.

 

ok, i looked under my dash. I guess its the same rubber plug that the hood release goes through, also that black hose in the picture which seems to go to the brake pedal. its way to the left under the dash, behind a bunch of wiring. I'm not sure what that other taped bundle of wires under the hose is, but it also goes through this plug.