Jeep 1997 Grand Cherokee Service Manual page 445

ZG
DIAGNOSIS AND TESTING (Continued)
(3) If the resistance is more than one ohm, check
the braided ground strap connected to the engine and
the vehicle body for being loose, corroded, or dam-
aged. Repair the ground strap connection, if required.
TEST 4
Test 4 checks the condition of the ground between
the antenna base and the vehicle body as follows:
(1) Connect one ohmmeter test lead to the vehicle
fender. Connect the other test lead to the outer crimp
on the antenna coaxial cable connector.
(2) The resistance should be less then one ohm.
(3) If the resistance is more then one ohm, clean
and/or tighten the antenna base to fender mounting
hardware.
NO OR POOR POWER ANTENNA OPERATION
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.
(1) Check the fuse in the junction block. If OK, go
to Step 2. If not OK, repair the shorted circuit or
component as required and replace the faulty fuse.
(2) Check for battery voltage at the fuse in the
junction block. If OK, go to Step 3. If not OK, repair
the open circuit to the fuse in the Power Distribution
Center (PDC) as required.
(3) Unplug the power antenna motor wire harness
connector from the junction block and use two
jumper wires to check the antenna operation. Con-
nect one end of one jumper wire to a known good
ground and attach one end of the other jumper wire
to a good battery feed. Test the antenna operation as
follows:
NOTE: The power antenna will not operate in the
down direction when it is fully-retracted, or in the
up direction when
switches within the
designed to prevent the motor from operating
beyond the antenna up and down limits.
(a) To test the antenna Up operation, connect
the ground jumper to the power antenna up control
circuit cavity of the power antenna motor wire har-
ness connector; and, connect the battery feed
GROUP 8M - PASSIVE
STEERING COLUMN,
it is fully-extended.
power antenna unit
jumper to the power antenna driver circuit cavity
of the power antenna motor wire harness connec-
tor.
(b) To test the antenna Down operation, connect
the ground jumper to the power antenna driver cir-
cuit cavity of the power antenna motor wire har-
ness connector; and, connect the battery feed
jumper to the power antenna down control circuit
cavity of the power antenna motor wire harness
connector.
(4) If the antenna mast fails to operate in one or
both directions, replace the faulty power antenna
unit. If the antenna mast operates in both directions,
test the antenna relay as described in this group.
ANTENNA RELAY
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
RESTRAINT
STEERING
OR
INSTRUMENT PANEL COMPONENT DIAGNOSIS OR
SERVICE. FAILURE TO TAKE THE PROPER PRE-
CAUTIONS COULD RESULT IN ACCIDENTAL AIR-
BAG DEPLOYMENT AND POSSIBLE PERSONAL
INJURY.
(1) Remove the antenna relay from the junction
block as described in this group. Go to Step 2.
(2) Check for continuity between the relay ground
circuit cavity in the junction block and a known good
ground. There should be continuity. If OK, go to Step
3. If not OK, repair the open circuit as required.
(3) Check for battery voltage at the relay fused
B(+) circuit cavity in the junction block. If OK, go to
Step 4. If not OK, repair the open circuit to the fuse
in the junction block as required.
(4) Turn the ignition switch to the On position.
Check for battery voltage at the relay radio 12 volt
output circuit cavity in the junction block. There
should be voltage with the radio turned on, and no
voltage with the radio turned off. If OK, replace the
faulty relay. If not OK, repair the open circuit to the
radio as required.
Limit
are
AUDIO SYSTEMS
TO GROUP 8M
SYSTEMS BEFORE
WHEEL, STEERING
8F - 9
- PASSIVE
ATTEMPTING
COLUMN, OR