How to utilize stock speaker wire

4BangerStanger

CarAudio.com Enthusiast
Apr 23, 2019
70
3
DFW
I'm about to installing active components (Silver Flute 6.5" and Seas Prestige 1" tweeters powered by a Tarmps 4 00x4) in my Mustang. I know that I can still through the Molex connectors to get the speaker wire in to the door to the mids. But, I've seen a lot of folks on here saying to just use the stock speaker wire. But, I'm having trouble visualizing how to do that. Do I run speaker wire from the amp (under the passenger seat) to the wire harness in the kick panel and splice the wires there? Also, the car has factory components, so the factory speaker wire splits off to the tweeters in the a-pillar at some point. How do they typically do that? Do they run the speakers in series? Is there some kind of passive crossover involved? I need to make sure I get full power and full range to the mids (crossovers will be handled by the deck). I'm really leaning toward drilling the molex, but I'd be lying if I said if didn't make me a little nervous.
 

4BangerStanger

CarAudio.com Enthusiast
Apr 23, 2019
70
3
DFW

Popwarhomie

Team Lethal Pressure
Jan 22, 2010
6,088
243
Florida
I used the stock 14 gauge in my ST. My factory amp was in the rear and I used a Rockford Fosgate DSR1 which plugged into the factory wiring harness and labeled what all wires were what so I could plug them into my aftermarket amp.

Find a wiring diagram that labels all the wiring colors and use that 9 wire wire to extend the factory wiring to where your new amps will be.
 

4BangerStanger

CarAudio.com Enthusiast
Apr 23, 2019
70
3
DFW
I used the stock 14 gauge in my ST. My factory amp was in the rear and I used a Rockford Fosgate DSR1 which plugged into the factory wiring harness and labeled what all wires were what so I could plug them into my aftermarket amp.

Find a wiring diagram that labels all the wiring colors and use that 9 wire wire to extend the factory wiring to where your new amps will be.
OK. I get what you're saying. I don't have a factory amp, so I'd just do the same thing off the back of the hu, which it easy enough. The only question is, if I do that, will I get a full range / full wattage signal at the mid? The stock wire splits off at some point and goes to the tweeters and mids. Running new wire to the tweeters will be no problem since they're in the a pillars. So, I'm only wanting to use the stock wiring for the mids. I just don't know how the stock competents are wired. Are they typically wired in a series with some sort of crossover on the speaker itself? If that's the case I'll be golden.
 

4BangerStanger

CarAudio.com Enthusiast
Apr 23, 2019
70
3
DFW
Found the diagram online. Looks like are just wired in series. So, as long as I disconnect the factory tweeter, I would be good, right? Also, I'm reading that the factory wire is 18ga. Is that sufficient for the 62 watts that the 400x4 is putting out?
 

Attachments

2RZ-FE

Senior VIP Member
Mar 14, 2011
360
45
Dixon, Ca
18awg should be OK for that power.

My Stratus has molex. No factory tweeters so I ran a new 16awg wire. Need to do a second run so i can run active. Installing those boots back over the molex is a pain in my car so I have been procrastinating.
 

keep_hope_alive

Acoustics Engineer
Premium Member
May 1, 2007
7,410
192
Quad Cities, IL
It's common to intercept and reuse stock wiring with the manufacturer puts a molex plug at the door jamb. As noted above the factory tweeter and door woofer are on the same wiring (but in parallel, not series). Simply put, they get the same signal because the passive crossover is mounted to the tweeter. This is pretty typical across all makes/models that don't have fully active factory systems (typically reserved for higher trim levels).

Be sure to tape-off the unused harness and it's helpful to wrap it in something soft (like foam or felt) so it doesn't rattle around in the dash.

I highly recommend soldering if you're splicing into factory wiring. And in your case you're cutting the factory wiring since the harness is still connected to the factory radio. It's usually frowned upon to do this, which is why running new wiring is preferred. Instead of cutting wiring behind the dash/radio, you could intercept the factory door wiring in the kick panel where cutting is less likely to cause issues in the future (9[wire wouldn't be needed in this instance). Wiring behind head units is under a lot of stress when the factory radio is removed and reinstalled. Knowing what wire is what may require access to an online service manual so you can get the door molex plug diagram.

If you do cut behind the factory radio, be sure to insulate/tape/heatshrink each wire separately to prevent shorting out. The factory wire covering (usually fabric or plastic split loom) needs to be pulled back and you'll find the factory wiring is likely secured in several places to help alleviate strain. Just take your time and try to make it be as strong and secure as the factory wiring was.

Note that the other benefit of 9-wire is that you can use 4 conductors to give the signal to the amp (connect to head unit outputs) and 4 conductors to power the factory speakers (connect to the speaker side of the harness). The 9th wire is for remote turn-on, for which you'll look for 12V when the car is on.
 

4BangerStanger

CarAudio.com Enthusiast
Apr 23, 2019
70
3
DFW
It's common to intercept and reuse stock wiring with the manufacturer puts a molex plug at the door jamb. As noted above the factory tweeter and door woofer are on the same wiring (but in parallel, not series). Simply put, they get the same signal because the passive crossover is mounted to the tweeter. This is pretty typical across all makes/models that don't have fully active factory systems (typically reserved for higher trim levels).

Be sure to tape-off the unused harness and it's helpful to wrap it in something soft (like foam or felt) so it doesn't rattle around in the dash.

I highly recommend soldering if you're splicing into factory wiring. And in your case you're cutting the factory wiring since the harness is still connected to the factory radio. It's usually frowned upon to do this, which is why running new wiring is preferred. Instead of cutting wiring behind the dash/radio, you could intercept the factory door wiring in the kick panel where cutting is less likely to cause issues in the future (9[wire wouldn't be needed in this instance). Wiring behind head units is under a lot of stress when the factory radio is removed and reinstalled. Knowing what wire is what may require access to an online service manual so you can get the door molex plug diagram.

If you do cut behind the factory radio, be sure to insulate/tape/heatshrink each wire separately to prevent shorting out. The factory wire covering (usually fabric or plastic split loom) needs to be pulled back and you'll find the factory wiring is likely secured in several places to help alleviate strain. Just take your time and try to make it be as strong and secure as the factory wiring was.

Note that the other benefit of 9-wire is that you can use 4 conductors to give the signal to the amp (connect to head unit outputs) and 4 conductors to power the factory speakers (connect to the speaker side of the harness). The 9th wire is for remote turn-on, for which you'll look for 12V when the car is on.
I appreciate the advice. I just installed an aftermarket hu, I won't have to cut any of the factory wires. I also pre ran the RCAs and remote wire. So, it should be pretty painless.
 
  • Like
Reactions: keep_hope_alive