Wrangler 4WD L4-150 2.5L VIN P MFI (1998)
Brake Warning Indicator: Testing and Inspection
The diagnosis found here addresses an inoperative brake warning lamp condition. If the brake warning lamp stays on with the ignition switch in the On
position and the parking brake released, or comes on while driving, refer to Brakes and Traction Control/Brakes for diagnosis. If no service brake or
parking brake problem is found, the following procedure will help locate a short or open circuit, or a faulty switch.
WARNING: ON VEHICLES EQUIPPED WITH AIRBAGS, REFER TO AIRBAGS BEFORE ATTEMPTING ANY STEERING WHEEL,
STEERING COLUMN, OR INSTRUMENT PANEL COMPONENT DIAGNOSIS OR SERVICE. FAILURE TO TAKE THE PROPER
PRECAUTIONS COULD RESULT IN ACCIDENTAL AIRBAG DEPLOYMENT AND POSSIBLE PERSONAL INJURY.
1. Check the fuse in the fuseblock module. 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 fuse in the fuseblock module. If OK, go to Step 3. If not OK, repair the
open circuit to the ignition switch as required.
3. Turn the ignition switch to the Off position. Disconnect and isolate the battery negative cable. Unplug 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. Unplug 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 warning switch.
6. With both the park brake switch and the brake warning switch wire harness connectors still unplugged, check for continuity between the park
brake switch wire harness connector cavity and a good ground. There should be no continuity If OK, go to Step 7. If not OK, repair the short
circuit as required.
7. With the ignition switch held in the Start position, check for continuity between the park brake switch wire harness connector cavity and a good
ground. There should be continuity If OK, go to Step 8. If not OK, refer to Powertrain Management/Ignition Systems for diagnosis of the ignition
switch.
8. Turn the ignition switch to the Off position. Remove the instrument cluster. Check for continuity between the red brake warning lamp driver circuit
cavity of the left instrument cluster wire harness connector (connector A) and a good ground. There should be no continuity If OK, go to Step 9. If
not OK, repair the short circuit as required.
9. Check for continuity between the red brake warning lamp driver (G99) circuit cavities of the left instrument cluster wire harness connector
(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 circuit as required.
