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ATX Power

From AVIC411 Wiki

Powering Your AVIC Off an ATX Power Supply


Some of us overly dedicated AVIC hackers have a spare AVIC sitting around. Here's how to wire a spare PC ATX power supply up to power the AVIC.


STANDARD DISCLAIMER: Follow these instructions AT YOUR OWN RISK. No warranty or guarantee is given or implied. This process has worked for the author, but use your best judgement and if anything is not clear, STOP and do not proceed.



Getting Power


The author prefers to keep the wiring harness and the ATX power supply as close to stock/reusable as possible. In order to do so, a few hard drive power cable extenders and splitters were used to adapt the wiring harness to connect to the +12V Standby, GND and +12V wires on the ATX power supply. A handy reference for the connector pinouts can be found at this URL.


1. Cut the drive connector off one end of your extender/splitter cable. If it was an adapter for an IDE drive, you will want to use the Yellow wire (+12V DC) for your AVIC harness' +Battery connection. If it was a cable for a Serial ATA (SATA) drive, you will want to use the Yellow wire as well (+12V DC). Be careful, some adapter cables don't use consistent colored cables (the author had one adapter that put +12V on an orange colored wire). To be sure you are using the right wire, it is recommended you CAREFULLY use a voltmeter to measure the voltage from your intended supply wire and the intended COM (common, i.e. ground) wire.


2. Next, connect the harness Ground wire (black w/ silver C shaped connector) to the drive connector's COM (Black) wire.


3. Next, you will want to connect the harness ACC (Accessory) wire (the Red one on the AVIC harness) to a second +12V supply (Yellow wire on the drive connector). The Author has used a second drive power cable for this purpose (drive cable Yellow wire to harness ACC wire). DO NOT USE THE RED WIRE FROM THE DRIVE CABLE, as this is only +5V DC and not enough for the intended use. While the Author has not done so on his setup, you should also consider adding a switch or delay circuit to this connection as well, as the AVIC expects power on the +Battery line for a period of time before it is applied to the ACC line.


4. Now for the Parking Brake wire (light green). The Author suggests you use a toggle switch between the second drive cable connection's COM (Black) wire and the Parking Brake (light green) wire, which makes testing mods with a parking brake on or off possible (i.e. checks for forgotten "USE_SEPARATED_SAFETY_MODE=0", etc).


Turning On the Power Supply


Once the wiring harness is connected to the ATX supply (i.e. the adapter cables are plugged into the PS's drive cable) it's time to turn the supply on. If you have a power supply with an On/Off switch on the back, you will not need a separate switch for this task. If the supply does not have an On/Off switch on the back, you will need a single-throw switch to make/break a connection between two pins on the ATX 20/24 pin connector (PS_ON# and COM).


For Power Supplies with the On/Off switch:

1. You can use a wire to ground PS_ON# (Green wire) directly to COM (Black wire). Once this is done you can control application of power from the Power Supply's On/Off switch. If you put a switch on the ACC line, you will control startup/shutdown with that switch, and should have it off before applying power using the PS On/Off switch, then switch ACC on a few seconds later. Shutdown is the reverse of that process.


For Power Supplies without an On/Off switch:

You have 2 options:

1. Use the same method above, and plug the ATX power supply into a power strip with an On/Off switch.


- OR -


1. Wire PS_ON# into one side of a single-throw toggle switch and COM into the other side. When you wish to turn on the power supply, use the toggle switch to make a connection. To turn off the power supply, break the connection using the switch.


That's it. Apply power to your Power Supply, turn on ACC (or wait for the delay circuit to do so) and the AVIC should turn on and go through the normal startup process. If not, double check that your +Battery and ACC voltages are +12V DC while referencing the Ground wire when the power supply is on. If not, re-check your connections.

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