Jeep 1997 Grand Cherokee Service Manual page 442

8F - 6 AUDIO SYSTEMS
DIAGNOSIS AND TESTING (Continued)
RADIO
If the vehicle is equipped with remote radio
switches located on the backs of the steering wheel
spokes, and the problem being diagnosed is related to
one of the symptoms listed below, be certain to check
the remote radio switches and circuits as described
in this group, prior to attempting radio diagnosis or
repair.
• Stations changing with no remote radio switch
input
• Radio memory presets not working properly
• Volume changes with no remote radio switch
input
• Remote radio switch buttons taking on other
functions
• CD player skipping tracks
• Remote radio switch inoperative.
For circuit descriptions and diagrams, refer to
8W-47 - Audio System in Group 8W - Wiring Dia-
grams.
WARNING: ON VEHICLES EQUIPPED WITH AIR-
BAGS, REFER TO
RESTRAINT SYSTEMS BEFORE ATTEMPTING ANY
STEERING WHEEL,
INSTRUMENT PANEL COMPONENT DIAGNOSIS OR
SERVICE. FAILURE TO TAKE THE PROPER PRE-
CAUTIONS COULD RESULT IN ACCIDENTAL AIR-
BAG DEPLOYMENT AND POSSIBLE PERSONAL
INJURY.
CAUTION: The speaker output of the radio is a
"floating ground" system. Do not allow any speaker
lead to short to ground, as damage to the radio
may result.
(1) Check the fuse(s) in the junction block and the
Power Distribution Center (PDC). If OK, go to Step
2. If not OK, repair the shorted circuit or component
as required and replace the faulty fuse(s).
(2) Check for battery voltage at the fuse in the
PDC. If OK, go to Step 3. If not OK, repair the open
circuit to the battery as required.
(3) Turn the ignition switch to the On position.
Check for battery voltage at the fuse in the junction
block. If OK, go to Step 4. If not OK, repair the open
circuit to the ignition switch as required.
(4) Turn the ignition switch to the Off position.
Disconnect and isolate the battery negative cable.
Remove the instrument cluster bezel. Remove the
radio, but do not unplug the wire harness connectors.
Check for continuity between the radio chassis and a
good ground. There should be continuity. If OK, go to
Step 5. If not OK, repair the open radio chassis
ground circuit as required.
GROUP 8M - PASSIVE
STEERING COLUMN,
(5) Connect the battery negative cable. Turn the
ignition switch to the On position. Check for battery
voltage at the fused ignition switch output circuit
cavity of the left (gray) radio wire harness connector.
If OK, go to Step 6. If not OK, repair the open circuit
as required.
(6) Turn the ignition switch to the Off position.
Check for battery voltage at the fused B(+) circuit
cavity of the left (gray) radio wire harness connector.
If OK, replace the faulty radio. If not OK, repair the
open circuit to the Ignition-Off Draw (IOD) fuse as
required.
REMOTE RADIO SWITCH
WARNING: ON VEHICLES EQUIPPED WITH AIR-
BAGS, REFER
RESTRAINT SYSTEMS
STEERING WHEEL,
INSTRUMENT PANEL COMPONENT DIAGNOSIS OR
SERVICE. FAILURE TO TAKE THE PROPER PRE-
CAUTIONS COULD RESULT IN ACCIDENTAL AIR-
BAG DEPLOYMENT AND POSSIBLE PERSONAL
INJURY.
OR
(1) Disconnect and isolate the battery negative
cable. Wait two minutes for the airbag system capac-
itor to discharge before further service.
(2) Remove the remote radio switch as described in
this group.
(3) Use an ohmmeter to check the switch resis-
tance as shown in the Remote Radio Switch Test
chart.
Remote Radio Switch Test
Switch Position
Volume Up
Volume Down
Seek Up
Seek Down
Pre-Set Station Advance
(4) If the switch resistance checks OK, go to Step
5. If not OK, replace the faulty switch.
(5) Check for continuity between the ground cir-
cuit cavity of the switch wire harness connector and
a good ground. There should be continuity. If OK, go
to Step 6. If not OK, repair the open circuit as
required.
(6) Unplug the 24-way white wire harness connec-
tor from the Body Control Module (BCM). Check for
continuity between the radio control mux circuit cav-
ity of the remote radio switch wire harness connector
and a good ground. There should be no continuity. If
TO GROUP 8M -
BEFORE ATTEMPTING
STEERING COLUMN,
Resistance
7320 Ohms
1210 Ohms
4530 Ohms
2050 Ohms
10 Ohms
ZG
PASSIVE
OR