New Stereo headunit wiring questions - Chevelle Tech
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post #1 of 15 (permalink) Old Nov 24th, 13, 4:23 PM Thread Starter
JPS
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Joe
 
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New Stereo headunit wiring questions

Background: I'm about to make power/ground connections for an aftermarket [Pioneer] stereo headunit in a 70 EC sweep dash, original electric harness. [Plan to replace later when I go to a 3 hole SS dash, but for now original harness is functional].
Basic stereo install: no PreAmp, no Subs- just four 35 watt, 4 ohm speakers.
Pioneer headunit has two power supply leads: one for 'Switched Power' from ignition and one for 'Continuous Power' for Clock/Station Memory.

1. I'm presuming that a fuse-block connection at the 'IGN' terminal will be sufficient for 'Switched Power' ?
For this connection, what gauge wire is correct for powering the 45watt total [22 x 4 channel] headunit (see #3 below) ?

2. The headunit is so close to the 'LIGHTER' receptacle, that I'm tempted to make the 'Continuous Power' connection to it, since the only purpose it's used for now is charging a cellphone. Any conflicts?
2A. Alternately, for a Continuous Power' lead from the fuse blockwhich terminal should be used, and presuming it's a low current draw, which wire gauge is sufficient for Clock/Station Memory (see #3 below)?

3. FYI: the Pioneer supplied connection harness is made up of either 14 or 16 gauge leads- why wouldn't I just match the wire gauge of the harness?

4. Years ago, I installed a separate 'ground buss' on bottom edge of dash for my aftermarket [VDO] Oil & Temp gauges with backlighting circuits and I still have 4 terminals left there.
Any conflicts with connecting the headunit ground to this electric gauge 'ground buss'?

5. The Pioneer manual warns to "Use speakers over 50 watt (output value) and between 4 to 8 ohm impedance. Do not use 1ohm or 3 ohm speakers for this unit."
My speakers are Polk and specify 105 watt Peak Power Handling; 35 watt RMS.
I'm presuming I'm within the "over 50 watt (output value)" specification ?


Thanks for your inputs/suggestions- I hate doing it wrong the first time...
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post #2 of 15 (permalink) Old Nov 24th, 13, 6:05 PM
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Re: New Stereo headunit wiring questions

I used the lighter for the non switched wire and the ground went to the metal dash frame. If you have non stock exhaust.You will probably need some sort of amp.
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post #3 of 15 (permalink) Old Nov 24th, 13, 11:20 PM
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Re: New Stereo headunit wiring questions

Amps= Watts/Volts

Amps = 44/12.6

Amps= 3.5A

According to the American Wire Gauge chart a 3.5A load is fine for 24g wire.

You are more than able to use those terminals for ground, and the speakers are just fine for you to continue to use.

9 years and FINALLY she's drivable, just in time for my first born son.
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post #4 of 15 (permalink) Old Nov 25th, 13, 12:58 AM Thread Starter
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Re: New Stereo headunit wiring questions

Rod- thanks, but I mis-stated in original post about the Pioneer harness, they're not 14-16 gauge: The Ground & Continuous [Black, Yellow] leads are about 18 gauge, while the 'IGN' [Switched] lead, and all others for that matter, are smaller; maybe 22 or 24. [Eyeballed using my wire stripper.]
My logic thinks the Continuous [Yellow] power lead for Clock-Memory, drawing smaller current, should be the smaller conductor, like 22 or 24.
Likewise, the 'IGN' [Red] power lead for AMP-CD-Radio, drawing more current, should be the bigger 18 gauge.
They're sized exactly opposite. Am I missing something here?- [likely basic electrics and electronics].

Also: I looked and I'm already connected to the 'IGN' terminal on the fusebox for my Oil & Water electric gauges. Can the headunit share with the 2 gauges? All others are used too: gauge lights are on 'LMPS', I think the HEI distributor is on BATT, Electric choke on ACC.
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post #5 of 15 (permalink) Old Nov 26th, 13, 12:16 AM
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Rod
 
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Re: New Stereo headunit wiring questions

the HEI wouldn't shut off it is on BATT. HOWEVER even if the red wire is that smaller gauge it is still sufficient for that power consumption. Try connecting it up with red to IGN, and Yellow to Batt and see if it shuts off when it is supposed too, and retains memory. If not swap the two wires and try again. But which ever is the memory wire needs to be a 3A fuse. Does the head unit have its own fuse plugged into the back of the unit?

9 years and FINALLY she's drivable, just in time for my first born son.
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post #6 of 15 (permalink) Old Nov 26th, 13, 5:21 AM Thread Starter
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Re: New Stereo headunit wiring questions

Rod- I didn't re-trace all secondary circuits from the fusebox, but something is already tapped into the BATT terminal, but other than my gauges and their lighting, the only other power feeds would be to the electric choke and the HEI.
Although I don't see an apparent battery drain, I'm going to review the 'BATT' circuit to be sure its not draining needlessly. The car remains parked for weeks at a time and hasn't had any starting issues. However, I did need to replace the battery last Feb., and it was less than 2 years old, but was a cheap Autozone battery.

The headunit has a 10amp blade fuse in its chassis.
Still need a 3A fuse in-line for headunit memory power lead?

Thanks.
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post #7 of 15 (permalink) Old Nov 26th, 13, 11:15 AM
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Re: New Stereo headunit wiring questions

You SHOULD have a wire in your harness for your "clock" You could tap into that and use a 3A fuse inline for your memory lead, unless you have a fuse in your fuse block marked as clock. If you do not have a clock just replace it with a 3A if it is of something larger.

With regards to the BATT connection, do you have something that is switched by a toggle switch or by a solenoid?

BTW where in Cali are you located.

9 years and FINALLY she's drivable, just in time for my first born son.
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post #8 of 15 (permalink) Old Nov 26th, 13, 3:00 PM Thread Starter
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Re: New Stereo headunit wiring questions

Yeah, nothing is 'switched', so I'm going to retrace that 'BATT' line to see if it's really anything important...
It would be easier to run memory lead w/in-line 3A, direct from the 'clock' terminal.
...carlsbad.
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post #9 of 15 (permalink) Old Nov 26th, 13, 3:44 PM Thread Starter
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Re: New Stereo headunit wiring questions

Rod, I answered w/out reading carefully: "...or by a solenoid?"
Interesting; definitely possible. Going to do a close look w/a multi-meter.
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post #10 of 15 (permalink) Old Nov 26th, 13, 10:28 PM
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Re: New Stereo headunit wiring questions

Carlsbad is a LITTLE far to come help you with your wiring... I'm up north of Fresno.

9 years and FINALLY she's drivable, just in time for my first born son.
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post #11 of 15 (permalink) Old Nov 27th, 13, 10:03 PM
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Joe
 
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Re: New Stereo headunit wiring questions

There seems to be a lot of confusion in this thread...

First off some basics of basics for car stereos.

Most people just think the memory wire is just that, just for memory because it is constant hot. This is the main power supply feed for the whole stereo. This is a higher current battery feed for the electronics. The "ignition" wire is ONLY a trigger to tell the stereo it's okay to draw full current (if need be) from the hot/memory lead. Typically "yellow" is hot/battery connection and "red" is ignition/switched power. Some manufacturers such as Panasonic didn't even fuse the ignition line as it had a resistor in-line with it as it ultimately would trigger the base of a transistor or FET to turn on the stereo (very tiny current).

You may connect the "memory" wire to the cigarette lighter feed IF the wiring in your vehicle is up to snuff (meaning your fuse block is not a rusty piece of junk and/or riddled with voltage drops). The ignition/switched wire should connect to the ACCESSORY fuse aka radio fuse in the fuse block, or splice it into the original factory power feed wire. WHY? This is wire isn't hot during engine cranking as the ignition switch was designed to "shed" all unecessary loads during cranking. This will also allow you to enjoy tunes when the key is the proper accessory position when the engine is not running.

High end/high power stereos need a dedicated power feed (memory/hot) wired directly to the battery to avoid voltage drops.

Your speakers should work fine. Not sure on the above calculations on current/wiring as that would be for a given constant load, but as a rule of thumb, 18 gauge wire is fine for speakers from typical head units.... Longer runs (like into a car's trunk) and go no smaller than 16 ga.

Manufacturers are always going to use the tiny sized wires coming out the head-unit because 1) cost 2) they only have so many inches to provide output. It's up to the end user to splice the proper sized conductors on to these based on load and length of wire.

-If you don't stand for something, you'll fall for anything.
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post #12 of 15 (permalink) Old Nov 28th, 13, 6:42 PM Thread Starter
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Re: New Stereo headunit wiring questions

Rod- Thanks, though I didn't expect anyone to drive on over to give me a hand, I still appreciate the gesture.
Back in the 70's, I probably did a car stereo upgrade more than once incorrectly.
Now wiser and having a car in 'old' shape, worries me in terms of the 'original' electrical not being able to handle modern loads.

Coppertop- What you're saying is consistent w/my assertion above in #4.
That changes my wiring schematic and confirms basis as to why the 'Ground' & 'Continuous' leads are larger than the others.

Thanks.
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post #13 of 15 (permalink) Old Nov 28th, 13, 10:53 PM Thread Starter
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Re: New Stereo headunit wiring questions

Coppertop- the Pioneer manual states:
"when not connecting a rear speaker lead to a subwoofer", perform these connections:
"Yellow: Connect to the constant 12V supply terminal.
Red: Connect to terminal controlled by ignition switch (12V DC)
...etc"

...appears consistent with your statements, but are you also saying that I won't be able to play the radio unless the key is fully in the 'On' [Run] position?

BTW: hope everyone here @TC is having a happy thanksgiving...
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post #14 of 15 (permalink) Old Nov 29th, 13, 6:42 PM
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Re: New Stereo headunit wiring questions

Quote:
Originally Posted by JPS View Post
Coppertop- the Pioneer manual states:
"when not connecting a rear speaker lead to a subwoofer", perform these connections:
"Yellow: Connect to the constant 12V supply terminal.
Red: Connect to terminal controlled by ignition switch (12V DC)
...etc"

...appears consistent with your statements, but are you also saying that I won't be able to play the radio unless the key is fully in the 'On' [Run] position?

BTW: hope everyone here @TC is having a happy thanksgiving...
Joe,

I certainly ate my fill

Connect your "red" to the "ACC" (accessory) lug in the fuse block or splice it into the original power feed meant for the factory original radio.

This will allow you to listen to the radio when the key is in the "accessory" position when the engine is not running and when the engine is running normally in the "on" position. Don't use the key "ON" position with the engine not running just to listen to radio, that's why GM provides the "accessory" position.

-If you don't stand for something, you'll fall for anything.
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post #15 of 15 (permalink) Old Nov 30th, 13, 12:30 PM Thread Starter
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Re: New Stereo headunit wiring questions

Thanks Copper- makes sense.
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