Single under-dash power source for aftermarket accessories

**AndrewM** · 21st April 2016, 03:53 PM

Has anyone created a single 12V power supply "bus" under the dash, fed with a single wire from either the main or aux second battery via the firewall grommet to which you can wire all the aftermarket accessories? It may or may not also include fuses for each circuit. For starters I need to power LLAMS, UHF, Redarc TowPro and a TPMS.

I did all this on the old D3 but ended up with wires everywhere and think there has to be a better, neater way on the new D4.

There is also the issue of whether to power from the main or aux batteries or from an ignition source.

Tombie · 21st April 2016, 03:55 PM

Llams is self powered
Redarc should be wired direct for safety
Tpms should be switched (use aux socket as pick up)
UHF depending on your preference would be the only one to consider - I would go direct to main battery to reduce noise.

**rufusking** · 21st April 2016, 06:09 PM

The drivers side accessory socket (Cigar lighter) is a good accessory feed. The passenger side is separately fused but also feeds the rear of the centre console and the outlet in the cargo area.

**AnD3rew** · 21st April 2016, 07:20 PM

An experienced 4wder advised me to ensure the UHF is powered directly and not through ignition for two reasons.
- if you are at a campsite and expecting friends to join you you can leave the ignition off and the UHF on to hear approaching friends and guide them in to you.
- if you are the driver and have the keys in your pocket and fall off a cliff it allows your passengers to get on the radio and call for help even if hey don't have the keys.

I took his advice and while (knock on wood) I haven't needed it for the second reason, I often use it for the first reason.

**scarry** · 21st April 2016, 07:45 PM

Originally Posted by AnD3rew

An experienced 4wder advised me to ensure the UHF is powered directly and not through ignition for two reasons.
- if you are at a campsite and expecting friends to join you you can leave the ignition off and the UHF on to hear approaching friends and guide them in to you.
- if you are the driver and have the keys in your pocket and fall off a cliff it allows your passengers to get on the radio and call for help even if hey don't have the keys.

I took his advice and while (knock on wood) I haven't needed it for the second reason, I often use it for the first reason.

And on a D4,there is no accessories setting for the ignition.

Which at times can be a PITA.

**apom** · 21st April 2016, 07:52 PM

Originally Posted by scarry

And on a D4,there is no accessories setting for the ignition.

Which at times can be a PITA.

Isn't pushing the start button without touching the brake the same as accessories?

**Meken** · 21st April 2016, 08:40 PM

No that gets you ignition on - all the dash is lit up

**LandyAndy** · 21st April 2016, 08:41 PM

Even so,its pretty limited how long the ECU will let you use the acc function.The D4 is pretty power hungry it will either time you out or shut you down due to low power stored.
Andrew

**LandyAndy** · 21st April 2016, 08:44 PM

You can also press the wireless button and get the juke box happening after pressing the stop button,but it is timed and power available controled by the ECU.
Andrew

**rufusking** · 21st April 2016, 08:50 PM

The "Power Saver" relays (R1 and R3 behind the glovebox) that control the console outlets can be easily bridged with a fused jumper with spade connectors on each end. There is a thread on this way back somewhere. This will give you direct battery feed but run the risk of drawing down the battery if the devices are left on.

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