I installed an Alpine cd changer and ran cable from trunk to headunit and plugged in VOLALP adapter. How do I get my 12 volt constant power? I read in the archives that I could get it from the headunit harness but I don't know how to "splice" into this without compromising the power to the headunit. I read the wire map at bay13 and identified which wire is 12 volts, but I don't know how to use it. I'm so close...HELP! Thanks.

Rose, try this link:

http://au.geocities.com/ozbrick850/cdchangerinstall.html

The website is not mine, but I contributed this little bit to it a while ago. Hope it helps. I just jammed the tinned tip of the adapter wire into the back of the radio connector and it's bee almost 3 years without an incident.

Good luck

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Vladimir. 1998 S70. Base, 5-speed manual.

I had it installed by a shop, and i believe there is a plug hanging off the harness that goes to the radio, which you take 12vdc from.

OK. But how do you "take" 12 volts from this source?

Rose . First you need to expose the constant power wire, diagram is on Bay 13 @ volvospeed.com. then you can attach yellow wire. you can also buy a wire tap at radio shack or kmart to attach the wire. Disconnect battery just to be on safe side. Just remeber to keep you radio code handy.

Ah! That's what I needed to know! Just out of curiosity...I assume the headunit is drawing off of that power, so taping into that power for the cd changer does not affect the amount of power distributed to the headunit? I did not know devices could "share" the same power source. Thanks for the help.

Remember Ohm's law:

Never talk back to Mrs. Ohm.

If that doesn't help, try Ohm's other law:

E=I*R Translated into English, Voltage = Current * Resistance.

If you have one device drawing X amount of volts (i.e. the head unit) and you add in parallel another device that will draw Y amount of volts (i.e. the adapter) off of the SAME line, then Ohms law dictates that they will get their required voltage by increasing CURRENT DRAW through that wire. Since resistance remains pretty much constant, the circuit will automatically draw more current to keep the equation balanced. What this means:

The wire which was designed to carry a certain load now is carrying more. What amperage fuse is attached to this circuit? Just something to consider. More current will also generate more heat, so if the wire is undersized it's going to be like pushing water through a straw instead of a garden hose. Should any of this concern you?

I doubt it. The changer should indicate somewhere how many amps it draws on a dataplate or something. It probably won't be much. If you've got a couple of low current draw items pulling power off the same line, then as long as the wiring is adequate you shouldn't have a problem. I wired my CD changer's power source to the rear amplifier on my '89 and never had a problem. If it's too much juice, you'll just keep blowing fuses. That's what they are there for, to prevent you from overloading the wiring. Examples of higher current draw items: Electric radiator fans, fuel pumps, ECUs. I'm a bit rusty, but hopefully Elec. Eng. 101 has been helpful in explaining your situation. If you need more explanation, just email me specific questions and I'll try to help. If I can't I'll fire it over to my father; a Volvophile and Electrical Engineer both for many years longer than I've been alive.

-Jon
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1LT Jonathan T. Belmont-- '91 Coupe 165K 'Gustaf'

Glad to have been of help, enjoy your cd changer. Ps where did you buy your Volap adapter ?

I don't know to tell you the truth. My husband bought it but I think it's the wrong one. I have a '96 850 which I think requires the VOLIL adapter. I'll try this one and see if it works.

I will be installing this adapter on a 1996 850 today. I'll let you know if it works or not.

Well,you`ll have to drive your car to electrician just for safety reasons,and to do this:Direct from your battery take + and for negative ground take your car`s chasis.That will secure your constant 12 volts of power.Do not do this YOURSELF because i`m affraid of short-circuit.I`m sure this will help.