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Discussion Starter · #1 ·
Requirements:
• Skill Level: Basic mechanical and electrical understanding
• Time: 1/2 - 1 day
• Special Tools: Yes

Goal: Make use of the second factory battery tray and have the install look as factory as possible.

These are special crimpers used for "open barrel" terminals. You can search for "delphi crimpers" and find them. I forget where I got mine from, it's been a while, but you should expect to pay around $30.


The crimpers allow you to make this type of crimp, which is critical. If the crimp is not right, the terminals will not slide into the connector.


Instructions:
Step 1.
Start by installing the battery isolator.

Battery Isolator (GM P/N 12135194). GM calls this a "secondary auxiliary relay".


It goes on the firewall, up and left from the brake booster.


How you mount it is up to you. If your truck is like mine, then it doesn't have the needed studs from the factory. So I used M6 threaded inserts and flange bolts from ACE hardware.


Step 2.
Install the relay that controls the battery isolator. I acquired mine as kit that included the relay, connector, seals, terminals, TPA, and CPA from lsxtune.com

The mounting procedure is identical to that of the isolator. It is also placed on the firewall directly above the wire coming from the alternator.


Step 3.
Install the fuse holder intended for dual battery use. I purchased my holder (P/N 19116352) and cover (P/N 15881616) from gmpartseast. It is a direct swap with the single fuse holder.


With those items installed you have completed the install of the new hardware. Now it's time to tackle the wiring aspect. There are only 3 wires we need for this. Switched 12V (only hot when key is in ACC), constant 12V (always hot), and ground. Orange wire is used for switched 12V, red/wh is constant 12V, and black is ground. The two 12V wires will come from the fuse block and the ground will come from the passenger side head. The orange wire is technically the "ignition 3" circuit and is controlled by the BCM.

Step 4.
We need to add the connector that would be there if the truck originally came with the TP2 option. To get this started you need to remove the fuse block and expose the harness connectors underneath. The connector we need to tap is the middle one closest to the engine. Notice the single terminal in the upper right hand corner? That's the corner we will be adding to.


For this procedure your going to need two terminals (P/N 15304711) and GM specs 20 gauge wire for this. The factory colors are orange and red/white stripe. I found mine at eficonnection. You'll need to use those special crimpers at this point and make a red/wh and orange wire that looks like this. *there is a locating tab on the backside of this terminal that needs bent down in order to seat the connector*


Once you have that done, you need to remove the red TPA from the connector. When the terminals seat they won't be able to be removed without a special tool, the TPA is added insurance. I just used a small flat head screwdriver and it comes loose. Then insert the red/wh wire into A5 and orange wire into B4. Make sure to reinstall the TPA.




Then connect the ground. There is a factory grounding point on the passenger side head. In this pic I've already ran the ground and incorporated it into the factory wire loom.


At this point we have our wires from the fuse block and our ground. I also went as far as to replace my alternator wire with 1/0 and cleanup the wire loom. Here are some pics of that little process. I'll start from the fuse block and work towards the passenger side.










So now everything is cleaned up, with our three wires loose in the bottom left corner of the above pic. Now we're ready to add the connector for these wires. For this you're going to need TPA (P/N 12160826), Connector (P/N 12160825), 3 terminals (P/N 12045773), 3 seals (P/N 15324976), and one plug (P/N 12059168). And you end up with something like this. Route this harness along side the alternator wire and zip tie it to the alternator wire just below where the alternator wire is zip tied to the AC dryer. The pinout for this connector is Pin A=orange, Pin B=Ground, Pin C=Red/Wh, Pin D=plug




Technically at this point you could order the factory AC Delco Battery Cables for the TP2 option and plug and play. But those cable aren't cheap, I'm going bigger, and why buy when you can make your own cheaper.

Step 5.
At this point is when I would run the power and grounds for the second battery. You need to run power from the fuse holder (bus bar side) to the top post of the isolator and then run power from the bottom post of the isolator to the second battery. The battery is then grounded to the driver side head via a M10x1.5 bolt. I also ran a ground from the second battery to the frame.

Here you can see my two 1/0 grounds running from the battery (bottom of pic) to the head and to the frame. I had to drill and tap the frame. I also had to shorten up one of the bolts because it was bottoming out in the head.


 

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Discussion Starter · #2 ·
Step 6.
Now its time to tackle the harness that makes all this work. Start with the male connector that will plug into the one we zip tied to the alternator wire. Here is the sequence on how to make these connectors. Slide the seal onto the wire, crimp the wire to the terminal, slide the seal up to the terminal, crimp the seal to the end of the terminal, insert your terminals and plug, and attach the TPA. Use same pin out used for the male connector. For this side you need TPA (P/N 12160480), Connector (P/N 12160482), 3 terminals (P/N 12048074), 3 seals (P/N 15324976), and one plug (P/N 12059168).










This is what you need from the relay kit


You need to double up the ground terminal


From left to right you have the red wire from the engine harness, it goes to pin 30 on the relay. Orange wire from harness goes to pin 86 on the relay, black wires go to pin 85, and the 2nd red wire goes to the battery isolator.


So at this point we should have two wires coming off the relay. A red and a black. These two wires are going to go to the connector for the battery isolator. For that you'll need TPA (P/N 12052634), connector (P/N 12052641), 2 terminals (P/N 12160223), and two seals (P/N 15324976). The red/wh wire from the relay goes to Pin A and the black wire goes to Pin B. Once that is connected I loomed all the wires and ended up with this.


Plug it all in and clean everything up and you are done.




You'll need these little gems to screw onto the studs on the firewall above the motor. They're called speed nuts. They're the only thing that will thread onto the factory studs. I forget what size they were. They were the only black ones in the box.


Conclusion:
This is a very doable project. It does take some time, but the wiring is solid and looks like a pro did it.
 

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Discussion Starter · #3 ·
The following link will take you to a cart at mouser.com with all the necessary terminals, seals, plugs, connectors,... Between this cart and the relay kit from lsxtune (linked above). You'll have everything you'll need to make all the connections for the fuse block, ground, connector by the engine, relay, and isolator.

Mouser
 

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My NNBS truck (2013) did not have the fuse holder next to the battery and no factory provisions to mount one.
 

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Yeah, I saw that after I posted. Did you ever take a look at the battery fuse block on your '14?
 

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Your posting about factory dual battery setting is very detail, which save me a lot time to grab all necessary parts.

I have 2 questions that I could not find answer:

1) For the fuse holder (GM #: 19116352), what is the fuse amperage did you use for auxiliary battery?

2) For the 2 connectors GM #: 12160825 and GM #: 12160482, are they necessary? From budget saving point, those 2 connectors could be omitted, just run Black, Orange and Red wires from underhood driver-side fuse box all the way to auxiliary battery run relay (LSxTune #: CONN-75575), then from that relay to battery isolator.

Actually you just need 2 connectors, GM #: 12052641 (for battery isolator) and connect for the relay (LSxTune #: CONN-75575).
 

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Here is the answer:

The auxiliary battery provision can be used to supply electrical power to additional equipment that the customer may choose to add, such as a slide-in camper or trailer, without discharging the vehicles primary battery. The auxiliary battery relay closes when the engine is running, in order to allow the generator to charge the auxiliary battery. The relay opens when the engine is off, so that the accessories will not discharge the vehicles primary battery, which is used for engine starting. If the vehicle is equipped with an auxiliary battery, the relay will be located on the driver's side of the vehicle, next to the underhood electrical center.

Generally, a fuse should not be used in the STUD 1 Fuse 68 position of the underhood fuse block, if the vehicle is equipped with an auxiliary battery. A plastic plug may be installed in this position instead of a fuse. If a fuse is installed in this position, the accessories will discharge the primary battery in addition to the auxiliary battery.
 

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Discussion Starter · #12 ·
jz57 said:
Your posting about factory dual battery setting is very detail, which save me a lot time to grab all necessary parts.

I have 2 questions that I could not find answer:

1) For the fuse holder (GM #: 19116352), what is the fuse amperage did you use for auxiliary battery?

2) For the 2 connectors GM #: 12160825 and GM #: 12160482, are they necessary? From budget saving point, those 2 connectors could be omitted, just run Black, Orange and Red wires from underhood driver-side fuse box all the way to auxiliary battery run relay (LSxTune #: CONN-75575), then from that relay to battery isolator.

Actually you just need 2 connectors, GM #: 12052641 (for battery isolator) and connect for the relay (LSxTune #: CONN-75575).
1) I believe its 150 Amp

2) Not sure how to answer. I'm sure there are multiple ways to hook it up. The way I described is exactly how the service manual has it in the schematics.

PJorgen said:
Great write-up. Question - what is the advantage of two batteries? I understand they may be needed when starting a diesel, what would they add to a gasser?
Actually only one battery is called on when you turn the key to start. The dual batteries are only hooked together when the key is in the run position. Dual batteries are good if you're running a lot of accessories, you have the reserve of two batteries to draw from. So if you notice your lights dim when you turn something on or if you have stereo system that causes the lights to dim then dual batteries will help that.
 

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dhall9,

Thanks for your input for the thread.

Since there is no schematic, even I have read your posting about dual batteries setting numerous, I still have difficulty to understand how that aux battery kicking in to crank engine.

The primary battery is located on passenger-side, which supplies all electric power when the engine is not running, the 2ndary battery is located on driver-side, which

When ignition key is on, the battery isolator is closed, and the 2ndary battery is connected to the newly added 175Amp MEGA fuse, then what??

The main function of the 2ndary battery is more like for cranking.

dhall9 said:
Actually only one battery is called on when you turn the key to start. The dual batteries are only hooked together when the key is in the run position. Dual batteries are good if you're running a lot of accessories, you have the reserve of two batteries to draw from. So if you notice your lights dim when you turn something on or if you have stereo system that causes the lights to dim then dual batteries will help that.
 

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Maybe I just missed it, but where did this 2nd Red wire come from?

"From left to right you have the red wire from the engine harness, it goes to pin 30 on the relay. Orange wire from harness goes to pin 86 on the relay, black wires go to pin 85, and the 2nd red wire goes to the battery isolator.
 
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