Mechanics

STEREO SPEAKERS AND 12V ACCESSORY OUTLETS

1999 Chevrolet Blazer • 158,000 miles

I have replaced the factory stereo with an aftermarket ALPINE CDA-9856. I want to install 2 amps which will require rewiring the factory speakers to the amp, and possible replacing the speakers themselves. However, I need to know the location of all the speakers and the sizes and ohm ratings. There are no 6"x9" speakers in the back, but I would like to add some; just not sure how to mount them. Plus, can you tell me where there is an available hole that goes through the firewall that I can run a power cable through. My question may be trivial, but I just don't want to screw anything up. I know there are 2 speakers in the dash, 2 in the front doors & 2 in the back doors. Are there factory enclosures to mount 6"x9" speakers in the back? This is the first time I've ever had any questions about audio in any vehicle I've owned. But, I absolutely can't find any information I need anywhere on the internet. I sure hope you guys can help me out. I just can't find any info anywhere else.
I apologize for having two questions, but the 2 12v accessory outlets on the right side of the console at the bottom of the dash do not work. Is there a seperate fuse or can I wire them directly to the cigarette lighter or another interior power source, or us the fuse panel my only option?
Thank you,
S. Jenkins
LCpl, USMC ('91-'92)
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US.Marine9_11@yahoo.com
December 20, 2011.




Sorry, Marine we don't have that type of information on our database-I recommend you seek advice with an auto stereo shop-
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Rasmataz
Dec 20, 2011.
The 2 12v accessory outlets on the right side of the console at the bottom of the dash do not work. Is there a seperate fuse or can I wire them directly to the cigarette lighter or another interior power source, or us the fuse panel my only option?
Thank you,
S. Jenkins
LCpl, USMC ('91-'92)

The ohms are not that big of a deal. 8 ohms is the most common for home audio systems but 3.2, 4, and 6 ohms have also been used in cars. The resistance values are more for the proper operation of the amp inside the radio but you have to consider that the wires going to the speakers are going to have some resistance too. If you measure from the speaker plugs in the radio with an ohm meter, you'll typically find between 10 and 20 ohms for the total circuit. What's important, if you want to be that critical, is to look at the speaker resistance specified for your new radio. Very likely it will be listed as "4 TO 8 ohms", or something like that.

To add to the misery, every manufacturer uses speaker shapes and sizes that they are sure are better than anything anyone else has ever come up with before. Some have three mounting screw holes instead of four, and you will never find any aftermarket speaker that is a direct fit. I have a boxful of new GM speaker adapters that allow standard speakers to be used. You will find similar products at Best Buy.

If this is a normal amp like GM and Ford use, there will be a wire on your new radio to turn it on when the ignition switch and radio are turned on. It may be labeled "power antenna" but it does the same function. When GM and Ford use amps, they must be used with the matching radio for proper volume and clear sound. When Chrysler uses amps, they only change the tone for the shape of the vehicle. They never increase volume or power so any radio will work with any system.

If you have an amp designed to irritate other drivers, they have their own turn-on circuitry and use a fat gauge power wire connected directly to battery power. You might consider running it under the car instead of under the carpet where it can get crushed by the rear seat brackets, and popping into the rear through one of the rubber plugs in the floor. Be aware that starting with the '87 models, GM went from one of the best generators to by far the worst pile ever developed. Due to the design of their internal voltage regulator these generators develop huge voltage spikes that interfere with the many computers and their sensor signals, and they can damage that regulator and the internal diodes. It is very common to go through four to six generators in the life of the vehicle, and the load placed on the electrical system by obnoxiously huge amplifiers will cause that regulator to drive the generator harder to try to keep up with demand. That will add to the voltage spike problem. The one thing that will reduce the number of repeat generator failures is to have a fairly new battery installed. As batteries age, they will still crank the engine just fine, but they lose their ability to dampen and absorb those spikes. Batteries in GM vehicles seem to start allowing problems to develop when they get to be about three years old. The old battery will still work fine in an '86 or older vehicle with the better generator design.

If you do have to connect a large cable to battery power, never stuff it under the terminals on the battery. Those side post terminals have caused GM owners so much grief for many years that now Chrysler wants to get in on the action too on some of their cars. The surface area for the cable's electrical connection is very small and just barely good enough to pass the required very high current for the starter. Sticking anything between the battery and cable will degrade that electrical connection. That will REALLY let those voltage spikes cause all kinds of problems. Instead, look for a smaller positive cable that attaches with a bolt and nut to the under-hood fuse box. That is a better place to attach extra cables, but the existing cables and the stud should be cleaned up with sandpaper first to be sure they're shiny. Those connections cause a lot of intermittent problems on all brands of cars so be sure the nuts are tight.

I just acquired a big pile of GM wiring diagram books last week. I'll look through them to see if I can help with the power outlet problem. I never looked to see if they're on the same circuit as the lighter.

Caradiodoc
Dec 20, 2011.
Thanks caradiodoc,
I upgraded the alternator to a rebuilt out of a 78 Buick w/168 amp output. ALL battery cables are side post and I made them custom. All grounds and starter cable are 00ga, and 02Ga to the fuse panel. All of the audio wiring I planned on running under the dash and down the center under the console. I'm running 3 Eclipse amps; 1 mono sub amp RMS 2240w @ 1/2 ohm, the other two are 2 channel, full range for the mids & highs. I believe there are 6 current speakers (I want to add 6"x9"s in the back) total of 8 speakers since the amps are 1/2 ohm stable. I'm running 12-14Ga wire to all the speakers & 4Ga to the subs; 4Ga power wire and 0ga 6" ground. The speakers I currently have are MB Quart's and the 6"x9"s are Eclipse. All 4 ohm rated. The subs are 2 Rockford T1 12" and 4 Punch P2 8" (all subs are 4 ohm on one mono amp; all amps fan cooled) all ran with breakers instead of fuses. I custom molded the fiberglass sub enclosure so my wife would still have shopping room in the back. I do everything myself so I like making sure that absolutely nothing is visible. I used, I think close to 15-16 sq/yds of dynamat and rubber undercoating, and some fiberglass in the body. At moderate volume, you can't hear anything outside, and there's not a single rattle outside. I just don't know there "all" the speakers are or what sizes they are. I will eventually custom remake all of the door panels and the rear hatch panel & headliner. I don't spend hardly any money on any of my mods, just a lot of meticulous work. I guess that where my ADHD & OCD are really useful. Any diagrams relating to the wiring of speakers, radio, interior lights; basically anything interior would help me a lot and be greatly appreciated.
Thanks again.

The newest book I have is for a '92 and it shows the older style plugs that I thought were gone by that time. You should have two small 4-pin plugs at the radio for the speakers. One is blue and one is white. According to the harnesses I made for my test bench, the wire colors appear to be the same for both style of plugs.

In the blue plug, the dark blue and light blue are for the right rear speaker. The yellow and brown wires are for the left rear. In the white plug, the tan and gray wires are for the left front, and the dark green and light green are for the right front.

In the black 6-pin plug, the orange is the 12 volt memory wire and is always hot. The yellow is the switched 12 volts to turn the radio on with the ignition switch. Pink is the switched 12 volts for a power antenna or amp. Gray goes to the dash lights to adjust the display and back-lighting brightness when the headlamps are on. Brown is for the tail lights to tell the display to dim at night when the headlamps are turned on. Black is the ground wire.

They didn't have power outlets in '92 so I can't help with those.

Caradiodoc
Dec 20, 2011.

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