MM-010019-001, Rev. B
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Figure 9-8: Connection of White Ignition Sense Wire Using Vehicle Fuse and T-Tap Kit
9.4.2.1
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 typically identified as the
“white ignition switch wire” or the “ignition sense 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 on 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.
1.
Locate the switched ignition or “Accessory” power wire (typically at or near the vehicle’s fuse block
or in a vehicle wiring harness) that will be used for the switched ignition power source. It may be
necessary to consult the vehicle manufacturer’s wiring diagram.
2.
Route the white wire of the control head’s DC Power Cable from the back of the head to an area near
the switched ignition power source. At the back of the head, be sure to maintain a cable service loop
of at least six (6) inches.
3.
Cut a short section (6 to 8 inches) off the end of the white wire and strip each end of this short wire.
