Jeep XJ Manual page 9

XJ
DIAGNOSIS AND TESTING (Continued)
while driving, refer Base Brake System for vehicles
not equipped with the four wheel anti-lock brake sys-
tem, or refer to Antilock Brakes for vehicles
equipped with the four wheel anti-lock brake system
in the Diagnosis and Testing section of Group 5 -
Brakes for further diagnosis. If no brake system
problem is found, the following procedure will help
locate a short or open circuit, or a faulty switch. For
complete circuit diagrams, refer to Instrument
Cluster in the Contents of Group 8W - Wiring Dia-
grams.
(1) Check the fused ignition switch output (run/
start) 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) Turn the ignition switch to the On position.
Check for battery voltage at the fused ignition switch
output (run/start) fuse in the junction block. If OK,
go to Step 3. If not OK, repair the open fused ignition
switch output (run/start) circuit to the ignition switch
as required.
(3) Turn the ignition switch to the Off position.
Disconnect and isolate the battery negative cable.
Disconnect the wire harness connector at the park
brake switch. With the park brake released, check for
continuity between the park brake switch terminal
and a good ground. There should be no continuity. If
OK, go to Step 4. If not OK, adjust or replace the
faulty park brake switch.
(4) Disconnect the wire harness connector at the
brake warning switch. Check for continuity between
the two terminals of the brake warning switch. There
should be continuity. If OK, go to Step 5. If not OK,
replace the faulty brake warning switch.
(5) Check for continuity between each of the two
brake warning switch terminals and a good ground.
In each case, there should be no continuity. If OK, go
to Step 6. If not OK, replace the faulty brake warn-
ing switch.
(6) With both the park brake switch and the brake
warning switch wire harness connectors still discon-
nected, check for continuity between the red brake
warning indicator driver circuit cavity of the park
brake switch wire harness connector and a good
ground. There should be no continuity. If OK, go to
Step 7. If not OK, repair the shorted red brake warn-
ing indicator driver circuit as required.
(7) With the ignition switch held in the Start posi-
tion, check for continuity between the red brake
warning indicator driver circuit cavity of the park
brake switch wire harness connector and a good
ground. There should be continuity. If OK, go to Step
8. If not OK, repair the open red brake warning indi-
cator driver circuit to the ignition switch as required.
(8) Turn the ignition switch to the Off position.
Remove the instrument cluster. Check for continuity
INSTRUMENT PANEL SYSTEMS
between the red brake warning indicator driver cir-
cuit cavity of the instrument cluster wire harness
connector A and a good ground. There should be no
continuity. If OK, go to Step 9. If not OK, repair the
shorted red brake warning indicator driver circuit as
required.
(9) Check for continuity between the red brake
warning indicator driver circuit cavities of the instru-
ment cluster wire harness connector A and the brake
warning switch wire harness connector. There should
be continuity. If OK, replace the faulty bulb. If not
OK, repair the open red brake warning indicator
driver circuit as required.
FOUR-WHEEL DRIVE INDICATOR LAMP - FULL TIME
The diagnosis found here addresses an inoperative
four-wheel drive indicator lamp condition. If the
problem being diagnosed is related to lamp accuracy,
be certain to confirm that the problem is with the
lamp or switch and not with a damaged or inopera-
tive transfer case or transfer case linkage. Refer to
NV242 Diagnosis in the Diagnosis and Testing sec-
tion of Group 21 - Transmission for more informa-
tion. If no transfer case problem is found, the
following procedure will help locate a short or open
in the indicator lamp circuit. For complete circuit
diagrams, refer to Instrument Cluster in the Con-
tents of Group 8W - Wiring Diagrams.
(1) Check the fused ignition switch output (run/
start) 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) Turn the ignition switch to the On position.
Check for battery voltage at the fused ignition switch
output (run/start) fuse in the junction block. If OK,
go to Step 3. If not OK, repair the open fused ignition
switch output (run/start) circuit to the ignition switch
as required.
(3) Turn the ignition switch to the Off position.
Disconnect and isolate the battery negative cable.
Disconnect the transfer case switch wire harness con-
nector. Check for continuity between the ground cir-
cuit cavity of the transfer case switch wire harness
connector and a good ground. There should be conti-
nuity. If OK, go to Step 4. If not OK, repair the open
ground circuit to ground as required.
(4) Connect the battery negative cable. Turn the
ignition switch to the On position. Install a jumper
wire between the full time four wheel drive indicator
lamp driver circuit cavity of the transfer case switch
wire harness connector and a good ground. The full
time four-wheel drive indicator lamp should light. If
OK, replace the faulty transfer case switch. If not
OK, go to Step 5.
(5) Turn the ignition switch to the Off position.
Disconnect and isolate the battery negative cable.
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