Dodge ram truck 3500 1996 Service Manual page 449

BR
AUDIO SYSTEMS 8F • 5
DIAGNOSIS AND TESTING (Continued)
speaker operation, i f OK, replace the faulty radio. I f
not OK, disconnect and isolate the battery negative
cable, remove the test radio, and go to Step 5.
(5) Unplug the speaker wiring connector at the
speaker. Check for continuity between the speaker
feed (+) circuit cavities of the radio connector and the
speaker connector. Repeat the check between the
speaker return (-) circuit cavities of the radio connec­
tor and the speaker connector. In each case, there
should be continuity. I f OK with the Infinity speak­
ers, go to Step 6. I f OK with the non-Infinity speak­
ers, replace the faulty speaker. I f not OK, repair the
open circuit(s) as required.
(6) Check for continuity between the amplified
speaker (-) circuit cavity of the body half of the
speaker connector and a good ground. There should
be continuity. I f OK, go to Step 7. I f not OK, repair
the open circuit as required.
(7) Install the radio. Connect the battery negative
cable. Turn the radio on. Check for battery voltage at
the amplified speaker (+) circuit cavity of the speaker
connector. I f OK, replace the faulty speaker. I f not
OK, repair the open circuit to the filter choke/
speaker relay as required.
FILTER CHOKE/SPEAKER RELAY
The filter choke/speaker relay Is used to switch
power to the Individual speaker amplifiers used with
the Infinity premium speaker package. The choke
and relay are serviced only as a unit. I f the coaxial
speakers lack bass or low frequency response, while
no sound is noted at the woofers, the choke/relay is
suspect. However, before replacement make the fol­
lowing checks of the choke/relay circuits. For circuit
descriptions and diagrams, refer to 8W-47 - Audio
System in Group 8W - Wiring Diagrams.
(1) Check the fuse in the fuseblock module. I f OK,
go to Step 2. I f not OK, replace the faulty fuse.
(2) Check for battery voltage at the fuse in the
fuseblock module. I f OK, go to Step 3. I f not OK,
repair the open circuit as required.
(3) Unplug the choke/relay harness connector.
Check for battery voltage at the fused B(+) circuit
cavity of the choke/relay connector. I f OK, go to Step
4. I f not OK, repair the open circuit as required.
(4) Probe the ground circuit cavity of the choke/re­
lay connector. Check for continuity to a good ground.
There should be continuity. I f OK, go to Step 5. I f not
OK, repair the open circuit to ground as required.
(5) Turn the ignition switch to the On position and
turn the radio on. Check for battery voltage at the
radio 12-volt output circuit cavity of the choke/relay
connector. I f OK, go to Step 6. I f not OK, repair the
open circuit as required.
(6) Turn the radio and ignition switches to the Off
position. Connect the choke/relay connector. Check
for battery voltage at the amplified speaker (+) cir­
cuit cavity of the choke/relay connector. There should
be zero volts. Turn the Ignition and radio switches to
the On position. There should now be battery volt­
age. I f OK, repair the circuits from the choke/relay
connector to the speaker amplifiers as required. I f
not OK, replace the faulty choke/relay.
ANTENNA
The following four tests are used to diagnose the
antenna with an ohmmeter:
• Test 1 - Mast to ground test
• Test 2 - Tip-of-mast to tip-of-conductor test
• Test 3 - Body ground to battery ground test
• Test 4 - Body ground to coaxial shield test.
The ohmmeter test lead connections for each test
are shown in Antenna Tests (Fig. 1).
NOTE: This model has a two-piece antenna cable.
Tests 2 and 4 must be conducted in two steps to
isolate a coaxial cable problem; from the coaxial
cable connection under the right end of the instru­
ment panel near the right cowl side panel to the
antenna base, and then from the coaxial cable con­
nection to the radio chassis connection.
-o o-
2
4
-o o~
J898F-7
Fig. 1 Antenna Tests
T E S T 1
Test 1 determines i f the antenna mast is insulated
from the base. Proceed as follows:
(1) Disconnect the antenna cable lead from the
radio chassis and isolate.
(2) Connect one ohmmeter lead to the tip of the
antenna mast and the other lead to the antenna
base. Check for continuity.