Improvising a constant wire

[Odysseus]

Hello all! First post alert!

I have a 2005 Lincoln LS. As soon as I bought it, I upgraded the head unit and speakers, and it all worked great. Then one day, I hit a bump in the road and my radio cut off. I took a multimeter to it and found out I have 12 volts from the ignition wire going into the head unit, and zero volts on the constant (yellow) wire.

Took me a while to figure this out, but today I ran a wire from my battery to my front seats, and just to see if that constant wire was my problem, I cut the constant on the harness and twisted the new wire into it, going into the radio. I had a helper touch the wire to the battery, and what do you know, the radio powered on!

Rather than chasing down whatever short I have, I've decided I'm going to get an inline fuse and run a wire from my battery to my constant, similar to how I tested it.

A couple questions have stemmed from this chain of events, mainly just curious so that I break as little as possible.

1. Are there any issues with running a constant wire straight from the battery? It seems like it would accomplish the exact same thing the constant wire already does, you know, by having a constant voltage going into the radio. Anything I should be worried about, other than basic electrical safety?

2. If I run an inline fuse on that improvised constant wire, what amperage would be reasonable? I was considering a 10 amp fuse.

One of my biggest pet peeves is rednecked/half assed car audio and underglow, so the rest of my install already looks great. I'm just gonna redneck this and hopefully nothing more. I am NOT ready, or willing for that matter, to tear apart my interior and find that short. This will have to work for me.

Not sure if it's related to the short but I figured I'd mention it, traction control and ABS both have been acting up since the day my radio went out. I didn't come here to solve that problem, but if I ever want to find that short or if one of you knows a thing or two about Lincoln LS electrical, that gives us a good starting point.


TIA!

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[1aespinoza Premium Member]

As you did not mention this, I will ask. Did you check the radio fuse?

 

[Odysseus]

As you did not mention this, I will ask. Did you check the radio fuse?

Haha yes, I know someone has to ask. I checked both radio fuses that the car has and every single fuse on my fuse panel. All good. Even replaced the radio fuses for good measure, but no dice.

 

[1aespinoza Premium Member]

I checked both radio fuses that the car has and every single fuse on my fuse panel.

This sounds like a BCM problem. Take the car to Autozone to see if the OBD2 port is working. OBD2 Bus and radio may be linked.

 

[Odysseus]

This sounds like a BCM problem. Take the car to Autozone to see if the OBD2 port is working. OBD2 Bus and radio may be linked.

It works, I have a code reader. I use it daily with this car

 

[1aespinoza Premium Member]

It works, I have a code reader. I use it daily with this car

Since you have not messed with any wiring prior to this issue, I still think the BCM is to blame since traction control and ABS issues began at the same time. Hunt for an BCM pinout for car and trace those wires. I bet they run on the same color code.

 

[hispls 5,000+ posts]

I say there's no problem in running another 12V constant to your radio provided you're fused and put it somewhere safe. 10A fuse may or may not do for your head unit and it may suggest a size in the owners manual.

The only thing I'd be worried about is what's going on with the original, but as you say that's a whole other can of worms.

 

[Odysseus]

I say there's no problem in running another 12V constant to your radio provided you're fused and put it somewhere safe. 10A fuse may or may not do for your head unit and it may suggest a size in the owners manual.

I was going with 10A because that's what is the fuse under the wiring harness on the rear of the head unit.

 

[hispls 5,000+ posts]

I was going with 10A because that's what is the fuse under the wiring harness on the rear of the head unit.

Should be safe.

 

[Odysseus]

Update! Ran my new constant wire and of course forgot to feed it through my trim panels before connecting it, so it's just hanging out the front of my radio right now.

I'll fix that eventually but what's important is that it works and I haven't have any trouble running a 10 amp fuse.