Power system update

Any amp of significant size requires a large power cable preferably connected direct to battery. My amp (500 watts) required 4 gauge cable.

I routed the 4 gauge cable from the battery to the cubby in the rear. I accomplished this by running the power under the drivers sill plates and up to the rear cargo area. This left the passenger side sill plates open for audio cables, backup camera and other.

To connect the cable to the battery you can purchase a replacement fastener from most stereo shops which allows you to replace the stud in the battery cable with one that has a bolt to connect your new amp cable. See figure 1.

This new cable has the potential of passing several hundred (yes hundred) amps of current and MUST be fused close to the battery. I added an inline fuse on the inside fender behind the power distribution box as shown in figure 2. A proper fuse is one that is just slightly larger than the amp you are powering.

There is a large wire grommet about 6" in diameter below the master cylinder which leads into the trucks interior. See figure 1a. This is the most common place to get wiring into the truck. I drilleda 3/8" hole through both parts of the grommet and fed a 12 gauge wire through the hole. I then taped it to the new 4 gauge cable and pulled the larger cable through the grommet. I recommend pulling from the interior into the engine compartment. Its easier to pull the required 3' of wire this direction instead of 13' the other direction. A little soapy water on the large cable will help get it through the rubber. With a 3/8" hole the cable will self seal so no further sealant is required.

Run the cable along the sill plates as show in Figure 2 and 3. Both sill plates just snap in place. The front sill plate is part of the kick panel and does not need to be totally removed to route the cable. If you decide to take it completely out then remove the round plug/fastener in the kick panel first.

Make sure you tie wrap the new cable along the existing wires and keep it away from the studs that are protruding from the floor. We don't want anything rubbing the insulation off this high current cable.

With the rear panel removed (procedure here) it's easy to route the cable next to the seats and along the rear inner fender well (see Figure 5). From there it's a short distance under the carpet to the cubby. Just make a small slit inside the cubby to bring wires in. If you plan on adding a false floor, make sure the slit is below where the floor will end up. (figure 6)

For the ground I drilled a 3/8" hole near the slit. I installed a 3/8" stainless stud with a nut and star washer on both sides. From the inside I ran a short cable with ring terminal to the capacitor and on the outside I did the same but ran the other end of cable to the frame (see Figure 7)

Something else that you might consider is doing the "Big 3" upgrade. This is a common practice for guys running large amps. The big 3 upgrade includes :

1) Large alternator positive to battery positive
2) Large battery negative to chassis
3) Large chassis to engine block

On a final note your high current power system is only as good as its weakest point. So if you have a high resistance connection ANYWHERE in the system you are going to have issues.

There are a couple common types of large gauge connectors. Set screw style and crimp. The set screw style are expensive and can be bulky. The crimp style require special crimpers either large jaw style or a hammer blow. Both are not something the average home installer is going to have laying around.

As a rule I use the crimp style and solder the connection. Some people use this type and flatten with a hammer. I would NOT recommend this.

Click here to see a soldered crimp connector.

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Figure 1 (click for larger img)
Figure 1a (click for larger img)
Figure 2 (click for larger img)
Figure 3 (click for larger img)
Figure 4 (click for larger img)
Figure 5 (click for larger img)
Figure 6 (click for larger img)
Figure 7 (click for larger img)