No Lighter or Stereo Power

[DustyRoad]

Hi all, been coming to these forums for almost a year whenever I've had a common problem but never got around to registering.

I've been installing a sound system in my 91' L series and make a pretty damn stupid mistake that resulted in no power what so ever going to the stereo head unit or the cigarette lighter. The fan works fine, the AC is disconnected at the moment so I can't test that.

Now the mistake I made was when I was trying to set up the amplifier (very first time doing this) I decided to splice the 12v wire into the head units 12v supply.
When I turned on the ignition there was a spark at the join and no power.

Today after buying an amp wiring kit and studying up on how to do it properly I redid all the wiring, running it from the battery with a fuse, etc. I checked over all the fuses and wiring while doing this.
None of the fuses in the fuse box under the steering wheel column were broken, the fusible links near the battery don't seem burnt either, just a little oil and dirt on them. There was a pair missing but that would be unrelated.
The wires that I check were okay but I didn't take of panels and check the entire length.

I thought of just running another wire from the battery to the stereo as I don't need the lighter but I'd still need to solder it to the wire in the plug.


Cheers, hope the wall of text wasn't to hard to read.

[stilson]

Gotta be a fuse mate, check them again with a meter.

[Davidov]

Either a fuse or somewhere along the line its completely melted the 12v wire, which wouldnt at all be surprising as most amps run at 40A+ and require 4 Guage wire direct to battery, the 12v to the head unit would be something like 16 guage (<20 amp)?

I would just run a new wire, following the length of it is a lot of work to pull apart the dash and loom (where the loom is tied/bundled together are likely places for a burnt out wire as it would get the hottest).
If the wire is burnt out you will need to run a new one anyway so might aswell just run one.

[Alex]

It'll be the fuse in the main fuse box. Have another close look at the 'illumination' fuse I think it is. You'll notice the stereo fuse also protects the lighter, dash lights and interior light I THINK.

8 gauge wire is heavy enough for anything under 500watts RMS.

How you wired up the amp first time is extremely dangerous and you're lucky you didn't burn the car to the ground. Take it to an auto sparky and get them to check what you did is ok.

Did you run a proper earth?

Sent from my HTC Velocity 4G using Tapatalk 2

[steptoe]

and don't make error some of us older ones do in the power source of old wiring method. Sound systems used to be main power wire for stereo went through IGN & ACC with a constant battery supply to run a clock - hook up new stereo like this and you get problems in power delivery. I was blowing fuses when I ramped up the volume

It now seems to be big power supply is direct to battery / fuse and ACC & IGN get trickle supply to control switching of big power wire.

[Davidov]

8 gauge wire is heavy enough for anything under 500watts RMS.

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Who runs under 500W RMS?

Alex also brings up a good point about a proper earth. It must be equal size to the +12v or larger. And also be safely and properly secured as if it gets free it can be a huge hazard. If you have it connected in cabin like mine (lug to a bolt of the passenger chair mount) it should be well crimped & soldered, so that it cannot get loose.

Not enough humility is taken towards car stereo electronics unfortunately. They are VERY dangerous. To give you an idea of the power it has through it, i accidently welded a chrome-vanadium spanner to the battery mount.
Car batteries easily have enough power to kill.

[DustyRoad]

Hey all, thanks for all the replies. Didn't expect this many.

After all the suggestions to check the fuses again I went out and pulled out every fuse one by one. There was one that was broken, the position fuse. Replacing that seemed to fix the power problems.
Although I'm left wondering what the position fuse is actually for, if both the radio and lighter fuses were fine.

As for the ground Alex and David, I've got it bolted to the front passenger seat (the amp is sitting underneath it). I have crimped and soldered it. I make wiring harnesses for CAT Underground so I sure as hell hope my build quality is up to scratch.
As for the sizes you were talking about David, is that the wire gauge?
Because the earth wire supplied in the wiring kit is 18 AWG, a lot smaller than the 12v power.
The actual earth length is roughly 250mm.

Also how you were talking about the 16 AWG stereo power melting, is it possibly is has also melted the insulation (as well as the blown fuse) but is still currently working?


Last question, all 3 RCA cables supplied were far too long and I've got almost a meter coiled up near the amp. Is there going to be to much heat and risk melting the insulation?

Cheers.

[Davidov]

As for the sizes you were talking about David, is that the wire gauge?
Because the earth wire supplied in the wiring kit is 18 AWG, a lot smaller than the 12v power.
The actual earth length is roughly 250mm.

Also how you were talking about the 16 AWG stereo power melting, is it possibly is has also melted the insulation (as well as the blown fuse) but is still currently working?


Cheers.

Hi, it is possible it may have caused some sort of insulation damage, but it all depends.
What is the RMS rating for the AMP you have? I find it a bit strange that they gave you such small earth wire unless its a very low power unit. I was running a sony explode 600W (something like 200W RMS) for a while with 8AWG to the battery and ground, and that was the very smallest i would take it. Now that i have a JL700/5 (700W RMS) 8AWG would eventually burn out or could cause damage to the amp.

I will ammend my point about the earth wire in that over very short distance runs you can get away with using smaller wire. I probably wouldnt really go any smaller than one or two steps smaller to be safe.

But remember, the bigger, better quality wire you run to your amp and any speakers for that matter (up to a point) will make them run better and sound better. I noticed a huge difference upgrading to 4AWG with my JL amp.

[Alex]

Good advice from David there. Cabling is where the difference can be made, especially in high end/competition systems.

I suspect you probably blew the fuse when you were mucking around with the power and stuff behind the dash.

Ive blown this fuse sooo many times. Mainly because im too slack to take the negative off the battery before doing any major electrical work haha.

your RCA leads will be fine coiled up like that.

alex

[DustyRoad]

Thanks for the replies lads.
The RMS, which I'm assuming is the same as rated power is 140W with a 350W max.
Nothing special, its a Sony XM-SW1. The cheapest single channel Supercheap had.
I'm running the 12" subwoofer off the amp with the 2 5" and 2 6.5" speakers running off the head unit.
Didn't want to spend to much on the little old L series, but enough to keep the audiophile in me at bay.

As for the earth wire, it is far smaller than the power. If you think it's at risk in any way I can use the left over stuff from the 12v.
The wiring kit I bought was separate to the amp, a Sony kit I also got from Supercheap.
I actually just went to the supercheap website to get you a link to the wiring kit and I noticed what I've done wrong.
The 18 AWG was the REM wire, haha. The reason I stuffed that up is because I already had the REM soldered and ready to go with my own 16 gauge.
The earth is indeed 8 AWG, the same as the 12v.

I better go out there in the dark and change it before I go blasting my tunes on the way to work tomorrow!
Here's a link to that kit if you were curious.

And thanks for the RCA info Alex, I wasn't looking forward to finding a way to stretch out that much.

[Bantum]

Got any pics of your install ?

Especially of the connections, as we might be able tell what you've done by looking at it ...

[Alex]

So you used the amps trigger wire as the main power supply? Although you're not playing with mega amounts of power, I'd be changing that straight away.

To give you an idea I'm running 4guage with an inline fuse from the battery to a power distribution block which splits into 2 4guage cables, each going to a different amp. I'm running a 4x125wrms amp for my speakers and a 1000wrms monoblock to my subwoofer. 4guage does the job just fine.

Both my amps are under the seats and are earthed to the seat rail lugs using 4guage cabling. My earth leads are only about 10-15cm long. I used battery ring terminals (the big ones) for the earth connection to the seat rail/car body

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[DustyRoad]

It wasn't the main power I was using the trigger/rem for Alex, I was using it as the earth.
I changed it over to the 4 gauge straight after posting last night.

My set up is a baby version of yours. I'm using 4 gauge from the battery, then about 100mm til the inline fuse, then a single 4 gauge runs to the amp under the front passenger seat. I've earthed it the same way, onto the seat's mounting bolt with a ring terminal.

So then, all problems solved, yay!
Thanks for all the help fella's. I'll be sure to post some pics of the set up in the sound system section once I get it a bit more respectable lookin'. (namely the "custom" wooden faceplate on the head unit I made, heh heh)