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Home >> Jeep >> 2000 >> Grand Cherokee Laredo, 4.0 S, AWD >> Repair and Diagnosis >> Body & Frame >> Body, Cab Control Systems >> Body Control Modules >> System Tests >> Instrument Cluster >> Brake Indicator Not Operating Properly

Brake Indicator Not Operating Properly

  1. Ensure parking brake is released and brake fluid level is at proper level. Turn ignition off. Turn ignition on. If Red brake warning light never comes on, go to next step. If Red brake warning light comes on and never turns off, go to step  3. If Red brake warning light illuminates for about 4 seconds and then goes out, go to step  12.
  2. Turn ignition off. Access rear of Mechanical Instrument Cluster (MIC) and replace Red brake bulb with a known-good bulb. Cycle ignition from off to on position. If Red brake warning light illuminates, repair is complete. If Red brake warning light does not illuminate, replace instrument cluster printed circuit board. See appropriate INSTRUMENT PANELS article. Perform BODY VERIFICATION TEST  under VERIFICATION TESTS.
  3. Turn ignition on. Using scan tool, select ANTI-LOCK BRAKES then SENSORS. Read BRAKE FLUID LEVEL voltage. If voltage is 0-.99 volt, go to next step. If voltage is 1.0-3.75 volts, go to step  6. If voltage is greater than 3.76 volts, go to step  9.
  4. Disconnect Controller Anti-Lock Brake (CAB) connector. See Figure. Disconnect brake warning indicator switch (brake fluid level) connector located on master cylinder. Using DVOM, measure resistance between ground and brake warning indicator switch connector terminal No. 2 (Gray/Black wire). If resistance is greater than 1000 ohms, go to next step. If resistance is less than 1000 ohms, repair short to ground in Gray/Black wire between brake warning indicator switch and CAB. Perform BODY VERIFICATION TEST  under VERIFICATION TESTS.
  5. Replace brake warning indicator switch. Perform BODY VERIFICATION TEST  under VERIFICATION TESTS.
  6. Block wheels and release parking brake. Turn ignition off. Remove Mechanical Instrument Cluster (MIC) and disconnect connector. Using DVOM, measure resistance between ground and MIC connector terminal No. 5 (Gray/Black wire). See Figure. If resistance is less than 100 ohms, go to next step. If resistance is greater than 100 ohms, go to step  8.
  7. Turn ignition off. Disconnect parking brake switch connector. Using DVOM, measure resistance between ground and parking brake switch connector terminal No. 2 (Gray/Black wire). If resistance is greater than 5 ohms, replace parking brake switch. Perform BODY VERIFICATION TEST  under VERIFICATION TESTS. If resistance is less than 5 ohms, repair short to ground in Gray/Black wire between parking brake switch and MIC. Perform BODY VERIFICATION TEST  under VERIFICATION TESTS.
  8. Replace instrument cluster printed circuit board. See appropriate INSTRUMENT PANELS article. Perform BODY VERIFICATION TEST  under VERIFICATION TESTS.
  9. Disconnect brake warning indicator switch (brake fluid level) connector. Turn ignition off and ensure lights are off. Using DVOM, measure resistance between ground and brake warning indicator switch connector terminal No. 1 (Black wire). If resistance is less than 5 ohms, go to next step. If resistance is greater than 5 ohms, repair open in Black wire between CAB and brake warning indicator switch. Perform BODY VERIFICATION TEST  under VERIFICATION TESTS.
  10. Disconnect Controller Anti-Lock Brake (CAB) connector. Using DVOM, measure resistance of Gray/Black wire between CAB connector terminal No. 21 and brake warning indicator switch (brake fluid level). See Figure. If resistance is less than 5 ohms, go to next step. If resistance is greater than 5 ohms, repair open in Gray/Black wire between CAB and brake warning indicator switch. Perform BODY VERIFICATION TEST  under VERIFICATION TESTS.
  11. Replace brake warning indicator switch. Perform BODY VERIFICATION TEST  under VERIFICATION TESTS.
  12. Turn ignition on. Set parking brake. If Red brake warning indicator does not come on, go to next step. If Red brake warning indicator comes on steady, test is complete, Check for any symptom related DTCs. Perform BODY VERIFICATION TEST  under VERIFICATION TESTS.
  13. Turn ignition off. Remove MIC and disconnect connector. Set parking brake. Using DVOM, measure resistance between ground and MIC connector terminal No. 5 (Gray/Black wire). See Figure. If resistance is greater than 5 ohms, go to next step. If resistance is less than 5 ohms, replace instrument cluster printed circuit board. See appropriate INSTRUMENT PANELS article. Perform BODY VERIFICATION TEST  under VERIFICATION TESTS.
  14. Using DVOM, measure resistance of Gray/Black wire between MIC connector terminal No. 5 and parking brake switch. If resistance is less than 5 ohms, replace parking brake switch. Perform BODY VERIFICATION TEST  under VERIFICATION TESTS. If resistance is greater than 5 ohms, repair open in Gray/Black wire between CAB and parking brake switch. Perform BODY VERIFICATION TEST  under VERIFICATION TESTS.
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