Installing An Auxillary Battery

[lpdyer1]

This is my first post, so hopefully I am doing it in the right place. I have a 2008 GMC Sierra. It has a provision for an auxillary battery under the hood. I want to add an aux. battery but I need to know how to hook it up. What would the wiring be. Can someone help?

[bill190]

If no one else can give you an easy answer to this...

 

On the wiring diagram, I see the aux battery associated with "Relay-Run (12129716)", and "Relay-Aux Battery (900_relay_aux_batt 001)". Then the aux battery is connected to ground, then to "Power Distribution junction block Page - pwr_dist-3" and one "Relay-Aux Battery (900_relay_aux_batt 001)" contact. The other "Relay-Aux Battery (900_relay_aux_batt 001)" contact is connected to "Charging Generator Page -Gas -3". Then the coil of "Relay-Aux Battery (900_relay_aux_batt 001)" is connected to ground and a contact of "Relay-Run (12129716)".

 

In other words, 2 relays one of which you might already have, associated wiring (some of which might already be there?), and the battery. At least two of these wires are special fusible link wires.

 

Since the relays for this would need to be rated for continuous duty (which the factory relays would be) and because two of the wires are special fusible link wires, I would recommend getting all factory parts from your GM dealer

 

So of you want to do it totally the factory way, I would go to your GM dealer and ask if they have a kit for this or could order the parts for this. Perhaps they could tell you what additional was needed to be installed?

 

If that does not work and you understand electrical components and wiring, then get a GM factory Electrical Diagram Manual, then begin looking for component locations and wiring to see what is there and what needs to be added. Then go to your GM dealer and order the parts you need.

 

Or if you don't understand electrical wiring, have a GM dealer do this for you.

[fdlecuyer]

I just did that installation a month ago. I went to the dealer and order everything. The only thing the parts guy didn't knew was the terminal number for the fuse box. Because the signal to activate the relay that activate the solenoid comes from the fuse box

 

 

 

Your looking for pin A5 : Battery positive voltage TP2 and B4 : Ignition 3 voltage TP2 on the X2 connector of the fuse boxTerminal # 13525970 Tray #4