Circuit/System Testing

Rear Glass Antenna Testing

1. Inspect the radio antenna module grounding surfaces and the mounting hardware for any corrosion that may cause a poor ground.
   • If corrosion is noted, clean the grounding surfaces or hardware.
2. Ignition OFF, disconnect the harness connector at the radio antenna module.
3. Radio ON, test for B+ between the signal circuit terminal 1 and ground.
   • If less than the specified value, test the signal circuit for a short to ground or an open/high resistance. If the circuit tests normal, replace the radio.
4. The antenna coax is made up of two parts; a coax between the radio and the radio antenna module, and a coax between the radio antenna module and the antenna, which is part of the vehicle rear glass. Disconnect both coax cables from the radio and the radio antenna module.
5. Test for infinite resistance between the antenna coax center terminal and ground.
   • If less than the specified value, replace the antenna coax.
6. Test for less than 5 ohms on the antenna coax center terminal from end to end.
   • If greater than the specified range, replace the antenna coax.
7. Test for less than 5 ohms on the antenna coax outer shield from end to end.
   • If greater than the specified range, replace the antenna coax.
8. Test for infinite resistance between the coax center terminal and the outer shield.
   • If less than the specified value, replace the antenna coax.

Fixed Mast Antenna Testing

1. Ignition OFF, disconnect the radio antenna coax cable from the radio and the radio antenna.
2. Test for infinite resistance between the antenna coax center terminal and ground.
   • If less than the specified value, replace the antenna coax.
3. Test for less than 10 Ω on the antenna coax center terminal from end to end.
   • If greater than the specified range, replace the antenna coax.
4. Test for less than 10 Ω on the antenna coax outer shield from end to end.
   • If greater than the specified range, replace the antenna coax.
5. Test for infinite resistance between the coax center terminal and the outer shield.
   • If less than the specified value, replace the antenna coax.
6. Reconnect the coax to the radio antenna. Test for infinite resistance on the coax at the radio between the center terminal and the outer shield.
   • If less then specified value, replace the antenna.
7. Test for less than 10 Ω on the coax at the radio between the outer shield and ground.
   • If greater than specified value, clean the mounting surface of the antenna ground plane. If no corrosion found, replace the antenna.
8. If all circuits test normal, replace the radio.