The Stovebolt Site Forums The Shop Area The Electrical Bay The Radio Bench Install Tips 12 volt CD/Radio in a 6 volt vehicle

Hello,

If you are trying to install a modern 12 volt radio/CD/cassette Head Units into a 6 volt negative ground vehicle, below are some wiring diagrams and special wiring instructions.

Modern aftermarket automobile stereo in-dash radios CD/cassette Head Units require special wiring.

The RED wire that normally goes to the vehicle ignition Accessory switch is internally connected to a voltage sensing circuit. When the ignition is switched on, 12 volts is applied to the RED wire, the voltage sensing circuit senses voltage and turns on the CD player, pre-amplifier and power amplifier circuits (standby mode). They do this so you don't have to turn on the Head Units power switch to play a CD.

With the engine off ignition switched on or in the accessory position and the Head Units power switch switched off (standby mode), you can insert a CD into the Head Unit and it will power up full on and start playing without turning on the Head Units power switch.

If you do not remove 12 volts from the RED voltage sensing wire the Head Unit remains on or in a standby mode which will result in the battery to drain.

The Head Units on and off switch does not fully shut the Head unit off; you have to remove 12 volts from the RED voltage sensing wire (to shut off standby mode) to prevent the battery from draining.

The YELLOW wire has two functions; it supplies minimal amperage draw constant 12 volts to the microprocessors to maintain clock time and radio station presets (which is not enough to drain battery). The other function is to supply 12 volts to the Head Unit for main system power during standby and full On, when 12 volts is applied to the RED voltage sensing wire.

Obviously when the engine is running, the battery is charging, there are no dead battery issues.

There are two ways to disconnect the RED wire.
Automatic disconnect Diagram 1 Check picture
Manual disconnect Diagram 2 Check picture

JVC manual states this about Red wire. Check picture

Note:If you go the Toggle switch route you can save yourself a few bucks if you don't mind flipping another switch after switching the ignition switch off.

Go to this POST .
To add a 12 volt battery to your 6 volt vehicle without converting the whole
vehicles electrical system to 12 volts.

Thanks,

xfiles

Jorb,
so where do you get a memory management unit?

Hello, truckernix

They make them here Custom Autosound scroll down page and you will find it.
They also have 6 volt positve ground Power Inverters.

This is their Dealer page from there you can find a dealer to buy from.
This is their Tech support page.

I found one here Classic Parts might be the same product from Custom Autosound. $1.00 cheaper.

Thanks for the post Fix and inquiring.

Need more info let me know.

What I find intriguing is that it takes a 6 volt sense input but is actually handling 12 volts. Of course this is just a logic trigger level.

I am not a real wiz when comes to internal workings but I was thinking the same thing.
I was wonder what the minimum and maximum trigger voltage would be before you
smoked it or when it would not open and close the 12 volt contacts.
Maybe it would also work on a 12 volts input.
They really should not call it a memory maintenance module its function has nothing to
do with maintaining voltage to hold radio station preset memory.
That probably was the marketing departments idea.
I would call it a micro switch relay.
Also how much 12 volt amperage can be pulled through it.
One time I accidentally grounded a radio/CD head units power antenna trigger wire and the contacts welded shut,
the power antenna would not come down after turning off the radio/CD head unit.

Back to your original question.
I think,Internally the trigger input voltage must be completely separate from the pass through open and close contacts voltage.

Thanks

I bought my memory module from [url=http://www.vintagecarradio.com/accessories/custom-autosound.html]www.vintagecarradio.com[/url] Custom Autosound. I think it was around 20.00 and it kept the memory for my clock and all of the radio stations. Good product!

Auto Bob,
welcome to the Stovebolt. It is good to have you aboard!