MM-014763-001, Rev. E
61
5.
At the back of the control head, tie and stow the cable as necessary.
6.
For the positive 12-volt DC main power source connection, route the cable’s red wire to the location
of an
unswitched
12-volt DC power source, typically near the vehicle’s battery. Remove interior
panels, door kick panels, etc. Protect the wire from possible chafing as necessary. This is the control
head’s main DC power source.
7.
Obtain one of the waterproof (HFB-type) fuse holders included with the control head’s DC Power
Cable.
8.
Cut excess length from the red wire and splice the fuse holder into it, near the location of the
unswitched 12-volt DC power source connection point.
9.
Using an appropriate electrical terminal, connect the red wire to the unswitched DC power source. A
⅜
-inch ring terminal is included with the cable for this purpose, but another terminal type (not
supplied) may be used if required.
10.
Obtain the 5-amp AGC-type fuse included with the cable, and install it into the fuse holder.
Do not share the control head’s fuse with any other device. Doing so can cause excess
current to flow through the fuse, causing it to blow unnecessarily.
CAUTION
The fuse for the control head’s red wire is rated at 5 amperes. The 3-amp fuse included
with the cable must
not
be used for fusing the control head’s main DC power. It fuses
the head’s white wire.
8.3.4.2
Connect DC Power Cable’s White Wire
A review of the information presented in Section 8.2.1 (page 48) may be beneficial at this time. As
required per the chosen power-up configuration, connect the white wire by following one of the three
procedures presented in the respective sub-section that follows.
8.3.4.2.1
Control Head and Radio Turn on with Vehicle’s Ignition Switch/Key
With this wiring configuration, the control head and radio automatically turn on and off with the vehicle’s
ignition switch/key. The white wire of the control head’s DC Power Cable is sometimes referred to as the
“white ignition switch wire” or the “ignition sense input wire.” In this configuration, the white wire
connects to a switched power source, typically identified as “Accessory” power, that switches on and off
with the vehicle’s ignition switch/key. When using this configuration, the CH-721 control head’s
on/off/volume control must be left in the
position for automatic power-up/down to function properly.
The white ignition sense wire must be connected to a fused power source that switches
from approximately zero volts to approxi13.6 volts when the vehicle’s ignition
switch/key is turned from the OFF position to the ACCESSORY and RUN positions.
Use of a switched power source that is subject to voltage changes as a result of other
actions, such as opening a vehicle door, may result in undesirable radio operation and/or
a degradation of radio performance.
9.
Locate the vehicle’s switched ignition or “Accessory” power connection point that will be used for
the switched ignition 12-volt DC power source. This point is typically located at or near the vehicle’s
fuse panel. It may be necessary to consult the vehicle manufacturer’s wiring diagram.
