Batboard

I am planning an install in a new Impala. There will be a 100 watt low band Maratrac and a 100 watt VHF MCS2000. Where do I pass thru the firewall? Where do I connect for battery power? Is there any wiring under carpet on hump? Where to mount radios in trunk? How to mount base load antennas on rear? Hazzards to be aware of?

Firewall: If you look under the glove box on the floor, up towards the wheel-well, there is a large square rubber plug with a wire running through it. If you carefully slice the rubber/electrical tape on the bottom of the plug (underneath the car), you can pass a couple wires through it. Be very careful not to cut the other wires. I hear they're important.

Not sure about the hump. What kind of seats?

Under the hood on the passenger side, there are two terminals with red covers marked "POS AUX BATT". Drop a ring terminal over there and you'e got power all day long.

I used trunk-lip mounts.

Yes, it's a chevy.

If you need a little ignition sense power, there's the aux power drop under the glove box as well. It's in the owner's manual how to find it.

Stay away from the factory grommet on the passenger side firewall. It's too hard to access from under the car to route the wires, and if you nick that factory harness you are F%^&D since that is -the- harness from underhood to the rest of the car. I ran two 8ga. wires thru this hole, but in hind sight I never should have. Too much potential for things to go wrong.

There is a 3/4" hole with an oversized rubber plug on the firewall behind the rear exhaust manifold. One the LS and SS models, the floor shifter cable to the tranny goes thru it, and on 9C1 and base cars it is unused. You can run a few cables thru this hole safely, so long as you keep them tight to the firewall. I have my speaker cable going thru it and have had -zero- problems with heat or other wear.

Another option is to drill a 3/4" or 1" hole in the upper floor pan near the factory hole on the passenger side. My agency did that and has had great success with it. They drilled it about 1" down from the factory hole and haven't had an issue since...even with off roading and median hopping.

Power can be obtained from the aforementioned two studs on the underhood distribution blocks. With the Impala, it's a lose/lose scenario, since GM stupidly uses the starter as the common point for the B+ wires. The battery runs to the starter B+ stud, the alternator runs to the starter B+ stud and the underhood distribution blocks get their power from the starter B+ stud...since the battery and alternator are run to there. It is a poor design and it's your choice whether you use the battery or the two studs.

If you have a civilian Impala with the 3800, order the 125A Bosch alternator that the 9C1 has...I did and it makes a world of difference. Contact me via PM for more info if you'd like.

In the car, the factory harness is run along right rocker panel under the carpet. Run all your added wires there as there is ample room, plenty of points to secure them and it's recommended by GM.

For antennas, get out the 3/4" hole saw. Use the decklid or roof. The decklid has plenty of room for up to 3 antennas without getting crowded.

Get a slide out equipment shelf for the trunk to mount radios...there is no easy way and the gas tank sits right under the trunk's floorpan at the front of the trunk. There is also an access cover for the fuel tank to the right of center on the floorpan at the front of the trunk. It's wise not to cover or otherwise distrub that.

Where exactly in the hole by the rear manifold?

It's on the firewall, behind the rear manifold. If you have column shift, then it is only a rubber plug. On my LS, there is a 1/4" hard cable that goes thru it for the floor shifter.

Even with the cable, there is plenty of room for a power cable and some smaller leads.

Sweeet. I was looking for somewhere to more cables through. :>