Schematic Reference: Radio/Audio System Schematics

Always perform the Diagnostic System Check - Vehicle, before proceeding with these diagnostic procedures. Refer to Diagnostic System Check - Vehicle .

This diversity antenna system is comprised of 3 antenna grid patterns interfacing with the rear defog grid, a radio antenna module, a coax, and a 14-volt power feed from the radio to the antenna module.

In AM and WX mode, the system functions as follows:

The antenna module takes the signal from only the AM/FM1 antenna pattern on the rear window. The antenna module amplifies this signal and sends it to the radio. In this mode the radio does not supply any voltage to the center conductor of the coax and there is no feedback signal present on the coax.

In FM mode the system functions as follows:

The antenna module takes the best signal from 1 of the 3 FM antenna patterns on the rear window. The antenna module amplifies this signal and sends it to the radio. In this mode, the radio supplies 12 volts to the center conductor of the coax and this switches the module into FM mode. The radio also supplies a feedback signal, along the coax, to the AM/FM antenna module, which indicates the quality of the signal. Based on the measured input signal level and the feedback from the radio, the antenna module switches between the 3 antennas to find the best signal.

The following information lists the most probable cause of the concern to the least probable cause, followed by the appropriate test for that condition. If the test leads to the replacement of a component, always inspect for a poor connection before proceeding with the replacement. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs .

Perform the Antenna System Test and test the antenna coax cable prior to performing any of the following tests.

Poor Reception on Both AM and FM Bands

Poor Reception on AM Band Only

Poor Reception on FM Band Only