LEMON Manuals: Even more car manuals for everyone
Home >> Ford >> 2008 >> Edge SEL, FWD >> Repair and Diagnosis >> Electrical >> Gauges >> Information Center >> Diagnostic Tests >> Instrument Cluster (IC), Message Center and Warning Chimes >> Pinpoint Tests >> Pinpoint Test M: The Brake Warning Indicator Is Always On

Pinpoint Test M: The Brake Warning Indicator Is Always On

Refer to appropriate SYSTEM WIRING DIAGRAMS article, Instrument Cluster for schematic and connector information.

Normal Operation 

The brake warning indicator alerts the driver if any of the following brake system conditions are present: the parking brake is set, the brake fluid level is low or the ABS module detects a electronic brake distribution (EBD) failure.

When the parking brake is applied, the parking brake warning indicator switch grounds circuit CLS05 (BU/GY) to the smart junction box (SJB). The SJB detects the ground signal and sends the instrument cluster (IC) a message over the medium speed controller area network (MS-CAN) to illuminate the brake warning indicator.

The SJB provides a reference voltage to the brake fluid level switch on input circuit CMC19 (GY/VT) with the signal return on circuit RMC19 (YE/GY). The brake fluid level switch is grounded through circuit GD120 (BK/GN). When the brake fluid level is low, the brake fluid level switch closes the input signal circuit to ground, pulling the reference low. When the SJB detects the reference voltage pulled low, the SJB sends a message to the instrument cluster (IC) over the MS-CAN to turn on the brake warning indicator.

When an EBD failure is detected, the ABS module sends a signal to the instrument cluster (IC) over the communication network to illuminate the brake system warning indicator.

If the parking brake or brake fluid level status message is missing for less than 5 seconds, the brake warning remains in the last indication mode (on or off). If the parking brake or brake fluid level status message is missing for more than 5 seconds, the instrument cluster (IC) sets DTC U0140 in continuous memory and defaults the brake warning indicator on. If the instrument cluster (IC) looses communication with the ABS module or the ABS module is disconnected, the instrument cluster (IC) sets DTC U0121 in continuous memory and defaults the brake warning indicator on.

NOTE: If DTC U0121 is set in the instrument cluster (IC), the ABS warning indicator is also be illuminated.
NOTE: If DTC U0140 is set in the instrument cluster (IC), other observable symptoms may also be present such as tire pressure monitoring system (TPMS) warning indicator, backlighting and door ajar indication.
NOTE: If the brake system experiences an EBD failure, both the brake warning indicator and the ABS warning indicator illuminate.

This pinpoint test is intended to diagnose the following:

PINPOINT TEST M: THE BRAKE WARNING INDICATOR IS ALWAYS ON 

NOTE: Use the correct probe adapter(s) when making measurements. Failure to use the correct probe adapter(s) may damage the connector.
  1. M1 CHECK THE ABS WARNING LIGHT OPERATION 
    • Key in ON position.
    • Observe the ABS warning indicator and brake warning indicators following the instrument cluster (IC) prove-out.
    • Are both the ABS and brake warning indicators illuminated? 
    1. YES  : Go to Pinpoint Test N .
    2. NO  : Go to  M2.
  2. M2 CARRY OUT THE INSTRUMENT CLUSTER (IC) INDICATOR LAMP CONTROL ACTIVE COMMAND USING THE SCAN TOOL 
    • Enter the following diagnostic mode on the diagnostic tool: Instrument Cluster (IC) DataLogger
    • Select the instrument cluster (IC) brake warning indicator (BRK_LAMP) active command and command the brake warning indicator on and off. Observe the brake warning indicator.
    • Does the brake warning indicator illuminate when commanded on, and turn off when commanded off? 
    1. YES  : Go to  M3.
    2. NO  : Go to  M12.
  3. M3 RETRIEVE THE RECORDED DTCs FROM BOTH THE CONTINUOUS AND ON-DEMAND INSTRUMENT CLUSTER (IC) SELF-TESTS 
    • Check for recorded instrument cluster (IC) DTCs from the continuous and on-demand self-tests.
    • Are any DTCs recorded? 
    1. YES  : For DTC U0121, go to Pinpoint Test AH  .

      For DTC U0140, go to Pinpoint Test AI  .

      For all other DTCs, REFER to appropriate DTC Chart in this service information.

    2. NO  : Go to  M4.
  4. M4 RETRIEVE THE RECORDED DTCs FROM BOTH THE CONTINUOUS AND ON-DEMAND ABS MODULE SELF-TESTS 
    • Check for recorded ABS module DTCs from the continuous and on-demand self-tests.
    • Are any ABS module DTCs recorded? 
    1. YES  : REFER to VEHICLE DYNAMIC SYSTEMS article.
    2. NO  : Go to  M5.
  5. M5 RETRIEVE THE RECORDED DTCs FROM BOTH THE CONTINUOUS AND ON-DEMAND SJB SELF-TESTS 
    • Check for recorded SJB DTCs from the continuous and on-demand self-tests.
    • Are any SJB DTCs recorded? 
    1. YES  : For DTC B2479, go to  M6.

      For DTC C1125, go to  M8.

      All other SJB DTCs, REFER to appropriate DTC Chart in this service information.

    2. NO  : Go to  M12.
  6. M6 CHECK THE PARKING BRAKE WARNING INDICATOR SWITCH 
    • Disconnect: Parking Brake Warning Indicator Switch C2015
    • Observe the brake warning indicator.
    • Does the brake warning indicator continue to illuminate? 
    1. YES  : Go to  M7.
    2. NO  : INSTALL a new parking brake warning indicator switch. REFER to PARKING BRAKE & ACTUATION article. CLEAR the DTCs. REPEAT the self-test.
  7. M7 CHECK CIRCUIT CLS05 (BU/GY) FOR A SHORT TO GROUND 
    • Key in OFF position.
    • Disconnect: SJB C2280c
      • Fig 1: Checking Circuit For Short To Ground
      GF0032213Courtesy of FORD MOTOR CO.
    • Measure the resistance between the SJB C2280c-1, circuit CLS05 (BU/GY), harness side and ground.
    • Is the resistance greater than 10,000 ohms? 
    1. YES  : Go to  M11.
    2. NO  : REPAIR the circuit. CLEAR the DTCs. REPEAT the self-test.
  8. M8 CHECK THE SJB OPERATION USING THE SCAN TOOL 
    • Key in OFF position.
    • Disconnect: Brake Fluid Level Switch C124
      • Fig 2: Connecting Fused (5A) Jumper Wire Between Brake Fluid Level Switch C124-2 & C124-3, CMC19 (GY/VT) & GD120 (BK/GN)
      GF0032214Courtesy of FORD MOTOR CO.
    • Connect a fused (5A) jumper wire between the brake fluid level switch C124-2, circuit CMC19 (GY/VT), harness side and the brake fluid level switch C124-3, circuit RMC19 (YE/GY), harness side.
    • Key in ON position.
    • Monitor the brake warning indicator.
    • Does the brake warning indicator turn off? 
    1. YES  : REMOVE the jumper wire. INSTALL a new brake master cylinder. REFER to HYDRAULIC BRAKE ACTUATION article. CLEAR the DTCs. REPEAT the self-test.
    2. NO  : REMOVE the jumper wire. Go to  M9.
  9. M9 CHECK CIRCUIT CMC19 (GY/VT) FOR AN OPEN AND A SHORT TO GROUND 
    • Key in OFF position.
    • Disconnect: SJB C2280f
      • Fig 3: Measuring Resistance Between SJB C2280F-9, Circuit CMC19 (GY/VT) & Brake Fluid Level Switch C124-2
      GF0032215Courtesy of FORD MOTOR CO.
    • Measure the resistance between the SJB C2280f-9, circuit CMC19 (GY/VT), harness side and the brake fluid level switch C124-2, circuit CMC19 (GY/VT), harness side; and between the SJB C2280f-9, circuit CMC19 (GY/VT), harness side and ground.
    • Is the resistance less than 5 ohms between the SJB and the brake fluid level switch, and greater than 10,000 ohms between the SJB and ground? 
    1. YES  : Go to  M10.
    2. NO  : REPAIR the circuit. CLEAR the DTCs. REPEAT the self-test.
  10. M10 CHECK CIRCUIT RMC19 (YE/GY) FOR AN OPEN AND A SHORT TO GROUND 
      Fig 4: Measuring Resistance Between SJB C2280F-22, Circuit RMC19 (YE/GY) & Brake Fluid Level Switch C124-3
      GF0032216Courtesy of FORD MOTOR CO.
    • Measure the resistance between the SJB C2280f-22, circuit RMC19 (YE/GY), harness side and the brake fluid level switch C124-3, circuit RMC19 (YE/GY), harness side; and between the SJB C2280f-22, circuit RMC19 (YE/GY), harness side and ground.
    • Is the resistance less than 5 ohms between the SJB and the brake fluid level switch, and greater than 10,000 ohms between the SJB and ground? 
    1. YES  : Go to  M11.
    2. NO  : REPAIR the circuit. CLEAR the DTCs. REPEAT the self-test.
  11. M11 CHECK FOR CORRECT SJB OPERATION 
    • Disconnect all the SJB connectors.
    • Check for:
      • corrosion
      • damaged pins
      • pushed-out pins
    • Connect all the SJB connectors and make sure they seat correctly.
    • Operate the system and verify that the concern is still present.
    • Is the concern still present? 
    1. YES  : INSTALL a new SJB. REFER to MULTIFUNCTION ELECTRONIC MODULES article. TEST the system for normal operation.
    2. NO  : The system is operating correctly at this time. The concern may have been caused by a loose or corroded connector. CLEAR the DTCs. REPEAT the self-test.
  12. M12 CHECK FOR CORRECT INSTRUMENT CLUSTER (IC) OPERATION 
    • Disconnect the instrument cluster (IC) connector.
    • Check for:
      • corrosion
      • damaged pins
      • pushed-out pins
    • Connect the instrument cluster (IC) connector and make sure it seats correctly.
    • Operate the system and verify that the concern is still present.
    • Is the concern still present? 
    1. YES  : INSTALL a new instrument cluster (IC). REFER to Instrument Cluster (IC) . TEST the system for normal operation.
    2. NO  : The system is operating correctly at this time. The concern may have been caused by a loose or corroded connector. CLEAR the DTCs. REPEAT the self-test.
scientia non olet · About LEMON Manuals