Wire Tracing

Floppie — Sun, 19 Apr 2009 01:01:25 +0000

This morning, I decided that enough was enough. It’s time to get my driver side speakers working, damn it. None of them work – tweeter, door, or rear; all three of the passenger side ones and the subwoofer all work. This makes blown speakers a fairly unlikely cause.

So, I opened up my service manual, figured out exactly how the sound got from the head unit to the speakers, and went outside to get started. First things first; I disconnected the negative battery terminal and pulled out the head unit – nothing new there. I also pulled the back speakers out, which was real easy; took a look at the connections on the left rear speaker, noticed some loose aluminum leads sticking off one of them, and pulled it off. Then I came upstairs and copied down the diagram for the head unit’s wiring harness – where each wire goes and what it does.

Went back down, investigated things a bit, and noticed that there was some speaker wire running into the driver side door. Hmm, that’s a little odd, that should be in the stock wire housing, rather than next to it. Look over toward the center, by the pedals, and there’s some identical wire. I pulled on it a little bit and found that the other end didn’t lead anywhere. Hey, maybe that’s part of the problem.

The passenger side of my car, minus one seat

Looking at my wire diagram, I notice that the head unit doesn’t connect directly to any of the speakers – it goes through an amplifier. Fair enough, I should probably look at the amp wiring as well – come upstairs, find out where it is…it’s mounted on the bottom of the passenger seat. Awesome, I’ve got to pull the seat out. Get some instructions on that – turns out it’s actually pretty easy, four bolts to unscrew and a few wire harnesses to disconnect.

Go down, yank the seat, get the amp off (also real easy, it’s mounted on two bolts and held on by two nuts), and take a look to make sure all the wiring looks solid. It does. So I come back up, copy down the wire harness diagram for that as well (26 leads instead of 20, that’s 33% more fun!), and go down to see if I can find any obvious issues. I can’t. Then that purple wire that’s pigtailing off of the brown one (lead #1, switched power) behind the head unit catches my eye. I’d really like to know what that is.

The path that this mystery purple wire follows

So I trace it. I find that it leads from its position behind the head unit, down under the carpet on the passenger side, back along the base of the doorway, underneath the back seat, and finally back into the trunk. Upon reaching the trunk, it is spliced crudely (electrical tape) with a similar blue wire that has a grounding connector on the end. Except it isn’t connected to anything; I’d thought maybe it went to the subwoofer or something, but no. It was just sitting there, drawing juice back to ground against the chassis uselessly. So I wrapped the end in electrical tape to at least eliminate the grounding.

At this point I decided to go for a drive without the passenger seat in – just for fun. I plugged the head unit and amplifiers’ harnesses back in, reconnected the battery, and went. I found this odd side effect that my blinkers didn’t work, but I think that was because I didn’t reconnect the hazard light switch (it’s mounted on the head unit’s facade), because they work fine now.

When I got back, I decided it was time to do something about the extraneous wiring going throughout my car. In the back, near the sub, there was a fairly heavy-duty white cable that grounded against one of the screws under the back seat – except that it was cut roughly two feet from the end. So it was just a useless piece of aluminum and rubber. Pulled that out. There were also four pigtail connectors (with no wires leading off of them) connected to four of the amplifier’s wires – pulled those off and wrapped the spots they were connected to with electrical tape.

That white grounding cable that was cut a couple feet from the connector

[caption id="attachment_259" align="alignright" width="150" caption="Mystery purple and white cables, after removal, sitting on my passenger seat...which was sitting in the driveway "][/caption]Then it was time to do something about that damn purple wire. I decided that it couldn’t possibly be important since it wasn’t connected to anything, and therefore was just adding extra weight to the car. So I opened up the pigtail connector, pulled it off the brown wire (taped up the very excessive amount of exposed copper), and started pulling the purple one out. This ended up being a bit involved – had to take the panel at the base of the doorway off, among other things.

Under the back seat, I discovered that it was ziptied together with this thick silver cable. I reasoned it out that this couldn’t be serving any useful purpose either and I wanted it gone. So I got the pair of them out from under the back seat, up front through the floor, and out from under the carpet. Finally, these damn things are gone. I’m decently confident that the purple wire may have been the cause of my battery drain.

White and purple cables, showing the white cable's connectors

I’d just like to take a minute to rant about the previous owner of this car. As you can see from the pictures at the left, this mystery white cable was used to connect some sort of home audio equipment to the car. Home audio equipment has no place in your vehicle unless it’s a ricer show car, and if that be the case it should be an XBox and a big screen TV replacing the back seat or something along those lines. This, quite frankly, is ridiculous.

The bits of silver speaker wire that were visible before removing anything

Then I decided it was time to take a look at this speaker wire down near the driver’s feet. After pulling the plastic panel out from the underside of the dashboard, I found that this speaker wire wasn’t being used for speakers at all – it was being used as power/ground for the red light by my feet…the one that doesn’t work. Well, I’m down here, might as well pull this out too. So I get all the wires out, except the one that leads into the driver side door – it’s connected to something, I’m going to need to pull the door panel off to figure out what.

Finally, I decided that it was time to call it a day. I pulled out the vacuum, got the trunk rug real good (it’s still a bit discolored from boxes of cat litter, but I’ll get it taken care of), got the entire passenger side floor since I had the seat out, everything. Then I remounted the amp to the bottom of the seat, reconnected all the wire harnesses, bolted the seat back in, and finished up. Just for fun I took a picture of the resulting pile of extraneous bullshit that came out of my car, and of the nice clean passenger side with the seat back in place. I didn’t manage to get the speakers working, but at least I got some garbage out, and possibly fixed the drain.

After eight hours of fun today, I leave you with these beauties

The passenger side (taken from the driver side) after vacuuming everything and bolting the seat back in

The pile of extraneous shit that came out of my car today

Floppie's Blag » speakers

Wire Tracing