Part 2 of 2

RADIO NOISE SUPPRESSION GROUND STRAP
Radio Frequency Interference (RFI) and ElectroMagnetic Interference (EMI) noise suppression is accomplished primarily through circuitry internal to the radio receivers. These internal suppression devices are only serviced as part of the radio receiver.

External suppression devices that are used on this vehicle to control RFI or EMI noise include the following:
- Radio antenna base ground
- Radio receiver chassis ground wire or strap
- Engine-to-body ground strap(s)
- Exhaust system-to-body ground strap (4.7L engines only)
- Resistor-type spark plugs
- Radio suppression-type secondary ignition wiring.

For more information on the spark plugs and secondary ignition components, refer to IGNITION CONTROLS.

REMOTE SWITCHES
A remote radio switch option is available on models equipped with the AM/FM/CD/cassette/3-band graphic equalizer (RAZ sales code) radio receiver and the high-line Central Timer Module (CTM). (Refer to ELECTRONIC CONTROL MODULES/BODY CONTROL/CENTRAL TIMER MODULE - DESCRIPTION) for more information on this component.

Fig.14 Remote Radio Switches:

Two rocker-type switches are mounted in the sides of the rear (instrument panel side) steering wheel trim cover, The switch on the left spoke is the seek switch and has seek up, seek down, and preset station advance functions. The switch on the right spoke is the volume control switch and has volume up, and volume down functions. The switch on the right spoke also includes a "mode" control that allows the driver to sequentially select AM radio, FM radio, cassette player or CD player. The two switches are retained in mounting holes located on each side of the rear steering wheel trim cover by four latches that are integral to the switches.

The remote radio switches share a common steering wheel wire harness with the vehicle speed control switches. The steering wheel wire harness is connected to the instrument panel wire harness through the clockspring. (Refer to RESTRAINTS/CLOCKSPRING - DESCRIPTION) for more information on this component.

The remote radio switches are resistor multiplexed units that are hard wired to the high-line CTM through the clockspring. The CTM monitors the status of the remote radio switches and sends the proper switch status messages on the J1850 data bus network to the radio receiver. The electronic circuitry within the radio is programmed to respond to these remote radio switch status messages by adjusting the radio settings as requested.

For diagnosis of the CTM or the J1850 data bus, the use of a DRB scan tool and the proper Diagnostic Procedures are recommended. For more information on the features and control functions for each of the remote radio switches, see the owner's manual in the vehicle glove box.

SPEAKER
Standard
The standard equipment speaker system includes speakers in four locations. One full-range 16.5 centimeter (6.50 inch) diameter speaker is located in each front door. There is also one full-range speaker located in each rear cab side panel, 13.3 centimeter (5.25 inch) diameter units for the standard cab models, and 16.5 centimeter (6.50 inch) diameter units for the club cab models. On quad cab models, the 16.5 centimeter (6.50 inch) diameter full-range speaker units are located in each rear door, instead of in the cab side panel.

Each of the four full-range speakers used in the standard speaker system is driven by the amplifier that is integral to the factory-installed radio receiver.

Premium
The optional premium speaker system features Infinity model speakers in six locations. Each of the standard speakers in the four speaker stereo system are replaced with Infinity model speakers, and an additional 6.9 centimeter (2.75 inch) diameter Infinity dome tweeter is mounted high in the front door trim panels. The premium speaker system also includes an additional Infinity power amplifier. The total available power of the premium speaker system is about 120 watts.

The six Infinity speakers used in the premium speaker system are all driven by the radio receiver through an Infinity power amplifier.