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power source question

Printed From: the12volt.com
Forum Name: Relays
Forum Discription: Relay Diagrams, SPDT Relays, SPST Relays, DPDT Relays, Latching Relays, etc.
URL: https://www.the12volt.com/installbay/forum_posts.asp?tid=28036
Printed Date: July 13, 2025 at 8:56 PM


Topic: power source question

Posted By: Tahoe01
Subject: power source question
Date Posted: March 09, 2004 at 12:33 AM

I am planning a video system install for my 2001 Chevrolet Tahoe.

The system will consist of a 400W Inv, PS2, Video amp & (3) monitors.  I installed a P.I.E. aux input adapter for audio through the factory HU & it works great (retained OnStar, etc.).

My question is...Instead of pulling a wire from the battery through the firewall, can I use a source already inside the cabin?  My Tahoe does not have power seats.  However, in the instrument panel fuse block, there is a 25A power seat circuit breaker.  Is there an appropriate way to use power from the fuse block (through a relay) for the inv?  I also noticed (in a second utility panel under the dash) that there are unused sockets.  Would power be available from any of them?  A simple block diagram of my thoughts is attached.  The add-a-circuit(s) will be connected to circuit(s) powered with the radio (Retained Accessory Power).  I would just prefer to use a power source without having to push a wire through an already tight bundle of wires through the firewall.

I have had no luck in searches for valuable info on my Tahoe's electrical distribution.  I appreciate any info/insight that can be offered.posted_image




Replies:

Posted By: Teken
Date Posted: March 09, 2004 at 4:50 PM
1. The first thing you need to do is varify the current draw / demand from each unit. That would be the primer, as to weather or not you are able to use the empty 25 amp fused socket.

2. With regards to the other outlets, simply taking a voltage measurement will tell you if it is live.

You will of course need to varify that the unused socket(s) are indeed switched / unswitched 12 VDC with the ignition key in place.

That will only tell you if the socket is live, and if it is switched / unswitched.

You still do not know what current demand the socket is able to carry.

You could remove the panel and see what guage of wire is fused into place. If you are sure as to the diameter and guage, you then could proceed with caution.

GM's are notorious with using very large insulation wraps on smaller guage wires, which gives the appearence to a much larger wire bundle that is simply not there.

You know the results of using a smaller size wire, in a high current load, so be carefull.

At the end of the day, it is much safer to run a main power wire from the battery and to split the current supply using a simple fused power distribution block.


Regards

EVIL Teken




Posted By: Tahoe01
Date Posted: March 09, 2004 at 7:13 PM

Thanks for the reply, Teken.

I have the load info for each piece of the system.  Under 1A for each piece (monitors, video amp).  My plan is to add a 5A circuit to an existing circuit that has the appropriate switching.  The inverter on the other hand can handle loads up to a total of 320W continuously.  The PlayStation2 is an 80W load.  I will occasionally also use the inv to charge dig camera batteries, charge cell phone maybe, etc. (small loads only).  I plan to energize the relay carrying power to the inv with another circuit with the appropriate switching.  Possibly split the load of all monitors, video amp and relay to minimize load on each circuit.

I am in hopes that someone will have specific information on the Tahoe's power distribution and I'll be able to find an appropriate power source based on the info.  Hopefully, someone can also offer info on AWG of the factory conductors.  If this info is not offered through the forum, where can I obtain it (most economically)?

That said...you may be right Teken.  I'll probably end up running a wire from the battery through the firewall.  Any advice on how to best do it?  I have never and don't want to ruin the factory seal around the existing run or skin a wire trying to push another one through the opening that seems to be really tight.





Posted By: Mad Scientists
Date Posted: March 12, 2004 at 5:56 AM

 WRT the Tahoe wiring, see if a local shop uses ALLDATA information services.. they should be able to pull the entire wiring harness diagrams.

 My suggestion would be to pull a feed off the battery for all this... that inverter can draw over 30 amps @ full load.

 Regards,

 Jim






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