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Test J: Brake Warning Indicator Is Never On

NOTE: Perform all voltage and resistance tests using an Digital Volt-Ohm Meter (DVOM) with a minimum 10-megohm input impedance, unless stated otherwise in test procedure. Use ohmmeter to isolate wiring harness shorts or opens.
  1. Turn ignition switch to LOCK position. If brake warning indicator light does not illuminate, go to next step. If brake warning indicator light illuminates, go to step  5.
  2. Ensure parking brake is completely released and brake fluid reservoir is full. Turn ignition switch to RUN position. If brake warning indicator light illuminates, go to next step. If brake warning indicator light does not illuminate, go to step  4.
  3. Leave ignition switch in RUN position. If brake warning indicator light does not stay illuminated, system is working properly at this time. Verify the symptom. If brake warning indicator light stays illuminated, go to step  9.
  4. Connect Worldwide Diagnostic System (WDS) tester or New Generation Star (NGS) tester to Data Link Connector (DLC). DLC is located below instrument panel. See Figure. In active command mode, request BRK LMP ON. If brake warning indicator light does not illuminate, go step  7. If brake warning indicator light illuminates, go to step  17.
  5. Turn ignition switch to LOCK position. Disconnect Generic Electronic Module (GEM) 20-pin harness connector C201b. See Fig 1. GEM connector is located behind Central Junction Box (CJB). See Figure. Turn ignition switch to RUN position. If brake warning indicator light stays illuminated, go to next step. If brake warning indicator light does not stay illuminated, go to step  17.
  6. Turn ignition switch to LOCK position. Disconnect instrument cluster 16-pin harness connector C220b, located behind instrument cluster. SeeFigure. It may be necessary to remove instrument cluster to access connectors. See INSTRUMENT CLUSTER  under REMOVAL & INSTALLATION. Turn ignition switch to RUN position. Measure voltage between ground and instrument cluster harness connector C220b terminal No. 4 (Light Green/Yellow wire). See Figure. See WIRING DIAGRAMS . If battery voltage does not exist, replace instrument cluster printed circuit. See PRINTED CIRCUIT  under REMOVAL & INSTALLATION. If battery voltage exists, repair short circuit to power in Green/Yellow wire between GEM and instrument cluster. After repair, test system for normal operation.
  7. Turn ignition switch to LOCK position. Disconnect Generic Electronic Module (GEM) 20-pin harness connector C201b, located behind Central Junction Box (CJB). See Figure. Measure voltage between ground and GEM harness connector C201b terminal No. 20 (Light Green/Yellow wire). See Fig 1. If battery voltage does not exist, go to next step. If battery voltage exists, go to step  17.
  8. Disconnect instrument cluster 16-pin harness connector C220b, located behind instrument cluster. SeeFigure. It may be necessary to remove instrument cluster to access connectors. See INSTRUMENT CLUSTER  under REMOVAL & INSTALLATION. Measure resistance between instrument cluster harness connector C220b terminal No. 4 and GEM harness connector C201b terminal No. 20 (Light Green/Yellow wire). See Figure and Fig 1 . See WIRING DIAGRAMS . If resistance is less than 5 ohms, replace instrument cluster printed circuit. See PRINTED CIRCUIT  under REMOVAL & INSTALLATION. If resistance is more than 5 ohms, repair open circuit in Light Green/Yellow wire between instrument cluster and GEM. After repair, test system for normal operation.
  9. Ensure parking brake is completely released and brake fluid reservoir is full. If brake warning indicator light stays illuminated, go to next step. If brake warning indicator light does not stay illuminated, go to step  11.
  10. Disconnect instrument cluster 16-pin harness connector C220b, located behind instrument cluster. SeeFigure. It may be necessary to remove instrument cluster to access connectors. See INSTRUMENT CLUSTER  under REMOVAL & INSTALLATION. Measure resistance between ground and instrument cluster harness connector C220b terminal No. 4 (Light Green/Yellow wire). See Figure. If resistance is more than 10 k/ohms, replace instrument cluster printed circuit. See PRINTED CIRCUIT  under REMOVAL & INSTALLATION. If resistance is less than 10 k/ohms, repair short circuit to ground in Light Green/Yellow wire between instrument cluster and GEM. After repair, test system for normal operation.
  11. Turn ignition switch to LOCK position. Disconnect Generic Electronic Module (GEM) 26-pin harness connector C201c. See Fig 2. GEM harness connector is located behind Central Junction Box (CJB). See Figure. If brake warning indicator light does not stay on after initial test illumination (prove out), go to next step. If brake warning indicator light stays on after initial test illumination, go to step  13.
  12. Turn ignition switch to LOCK position. Disconnect parking brake position switch single terminal harness connector C306, located at left side under dash. See Figure. Measure resistance between ground and parking brake position switch single terminal harness connector C306 (Light Green wire). See Fig 3. See WIRING DIAGRAMS . If resistance is more than 10 k/ohms, replace parking brake position switch. If resistance is less than 10 k/ohms, repair short circuit to ground in Light Green wire between parking brake position switch and GEM. After repair, test system for normal operation.
  13. Turn ignition switch to LOCK position. Disconnect brake fluid level switch 3-pin harness connector C124. See Fig 4. Turn ignition switch to RUN position. If brake warning indicator light stays on after initial test illumination (prove out), go to next step. If brake indicator light does not stay on after initial test illumination, go to step  15.
  14. Ensure Generic Electronic Module (GEM) 26-pin harness connector C201c is disconnected. Measure resistance between ground and brake fluid level switch harness connector C124 terminal No. 3 (Light Green/Yellow wire). See Fig 4. See WIRING DIAGRAMS . If resistance is more than 10 k/ohms, go to step  17. If resistance is less than 10 k/ohms, repair short circuit to ground in Light Green/Yellow wire between brake fluid level switch and GEM. After repair, test system for normal operation.
  15. Turn ignition switch to LOCK position. Ensure that brake fluid reservoir is full. Measure resistance between brake fluid level switch harness connector C124 terminals No. 1 and 3 (component side). See Fig 4. If resistance is less than 5 ohms, replace brake fluid level switch. If resistance is more than 5 ohms, go to next step.
  16. Disconnect Anti-Lock Brake System (ABS) module 30-pin harness connector C135, located at left front of engine compartment. See Figure. Measure resistance between ground and brake fluid level switch harness connector C124 terminal No. 2 (Light Blue/Black wire). See Fig 5. See WIRING DIAGRAMS . If resistance is more than 10 k/ohms, check brake system. See appropriate ANTI-LOCK BRAKES SYSTEM article in BRAKES. If resistance is less than 10 k/ohms, repair open circuit in Light Blue/Black wire between ABS module and brake fluid level switch. After repair, test system for normal operation.
  17. Ensure all Generic Electronic Module (GEM) connectors are disconnected. GEM is located behind Central Junction Box (CJB). See Figure. Visually inspect GEM connectors for loose connections, pushed out pins or corrosion. If problem is found, repair as necessary. If no problem is found, reconnect GEM connectors and operate system to verify concern is still present. If concern is not present, clear DTCs and repeat self-test. If no concern is found at this point, system is operating correctly at this time. If concern still present, replace GEM. See GENERIC ELECTRONIC MODULE  under REMOVAL & INSTALLATION.
Fig 1: Identifying Generic Electronic Module Harness Connector C201b Terminals
G00013163Courtesy of FORD MOTOR CO.
Fig 2: Identifying Generic Electronic Module Harness Connector C201c Terminals
G00013164Courtesy of FORD MOTOR CO.
Fig 3: Identifying Parking Brake Switch Connector C306 Terminal
G00162074Courtesy of FORD MOTOR CO.
Fig 4: Identifying Brake Fluid Level Switch Connector C124 Terminals
G00191580Courtesy of FORD MOTOR CO.
Fig 5: Identifying ABS Module Harness Connector C135 Terminals
G00014416Courtesy of FORD MOTOR CO.
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