How to Wire Additional Accessories?

[Shelbrain 10+ year member]

I am preparing for an upcoming wiring project in my Impala and was wondering what is the best way to run additional accesories in a car.

For example, I currently have a radar detector and an XM tuner that need to be hardwired. The XM tuner is the Alpine TUA-020XM (has yellblk power connectors) In the future, I may want to two additional screens for the headrest. Where do I pull all this power from?

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[azbass 5,000+ posts]

use a relay and pull a constant from the batt to use with everything . use your deck rem to switch the relay on.

 

[Shelbrain 10+ year member]

According to the Peripheral GMCO I am going to purchase as my wiring harness, the instructions I read say not to use the 12v acc in the harness to power anything other than the radio. Where else could I pull power from? According to everything I read, this car does not have an acc wire, that is run through the databus.

 

[KaeZoo 10+ year member]

It does have an accessory wire; it just doesn't use the accessory wire to control the radio. You can tap the brown wire behind the key switch if you just want key-controlled accessories. The XM tuner needs a constant power source so you can tap that one behind the head unit. If you want other accessories to be controlled by the radio power, do as azbass said and use a relay controlled by the head unit's remote output wire.

 

[Shelbrain 10+ year member]

So I tap the power wire behind the headunit for the XM tuner? (just double checking) and then I use a relay from the 12v acc wire to run my accessories and for my remote turn on lead?

 

[KaeZoo 10+ year member]

Yes, connect the XM tuner to the YELLOW wire behind your head unit.

As for the other accessories, do you want them to be controlled by the key or by the head unit? If you want them to turn on/off with the head unit, use the head unit's remote wire to activate your relay. If you want them to be controlled by the key, use the key switch accessory wire instead.

 

[Shelbrain 10+ year member]

@KaeZoo (or anyone else): So if I go the relay route, can I just run one wire to the trunk and tap into it 3-4 times to power all my accessories (XM tuner, remote turn on, etc.) using the single output wire of the relay? Or is there a distribution block method which uses smaller power wires (16-18 awg) typically used for accessories?

 

[KaeZoo 10+ year member]

Yes, you can run one wire back and tap everything you need into it, with two caveats: The wire has to be able to handle the current draw of all your accessories, and so does whatever you use as a power source (connected to terminal 87 on the relay). Depending on where you make the connection, you'll probably want to fuse this wire. If you want to be neat you can use a barrier strip with jumpers to make each of your accessory connections in the trunk.

Note, again, the XM radio unit needs to be connected to CONSTANT power, not switched power.

 

[Shelbrain 10+ year member]

Do you have a link to a barrier strip you'd recommend? I am officially going to be doing the install the week after Thanksgiving so I am hoping to keep the friendly advice coming when my car is torn apart