Component Tests and General Diagnostics

CHECKING RADIO MAST ANTENNA
Unplug antenna lead-in at back of Radio and plug a test antenna into Radio. Make sure test antenna base is grounded to the vehicle chassis. Do not touch the mast. Check Radio reception in an area away from tall buildings, metal structures, power lines, fluorescent lighting and power tools. Tune to high and low ends of the dial on both AM and FM, checking weak and strong station reception. If reception is OK, the problem exists with antenna and/or its lead-in cable. If reception is still poor with test antenna, check for aftermarket equipment that may be causing complaint. If OK, service Radio.

Check Points For Lead-In Cables:

CHECKING LEAD-IN CABLES
In case of continued reception or noise complaints, always check the lead-in with a digital multimeter, refer to accompanying image and chart below for resistance values. If long jumper leads are not available, check center conductor continuity by jumping the antenna mast to ground and checking for continuity from the center conductor at Radio to ground.

Lead-in Cable Resistance Checks
Digital Multimeter Resistance measured
Probes at Points: in ohms

A and B less than 3.5
C and D� less than 0.2
A and D infinite
C and B infinite
A and C infinite
B and D infinite

Checking Resistance
When checking resistance, cautiously wiggle the lead-in tip and cable. Consistent readings as shown in the above table should always be obtained. If not, some portion of the lead-in is intermittent and lead-in should be replaced. Also try:

1. Running a braided ground strap to the antenna lead-in.

2. Changing the antenna lead-in.

3. Disconnecting the lead-in to check resistance.

4. Check in-line connection for corrosion or poor connection.