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Home >> Jeep >> 2021 >> Grand Cherokee L Laredo, AWD >> Repair and Diagnosis >> Brakes >> Traction Control >> Brake System Control Module (BSCM) - DTCS P05E0-00 To U3009-00 >> DTC Troubleshooting >> U3006-00-Control Module Input Power "A" Circuit/Open >> Diagnostic Test

Diagnostic Test

  1. CHECK FOR AN ACTIVE DTC 
    1. Perform any Service Bulletins that may apply.
    2. Turn the ignition on.
    3. With the scan tool, read BSCM DTCs and record on the repair order.
    4. With the scan tool, read and record Environmental Data to help identify the conditions in which the DTC was set.
    5. With the scan tool, erase BSCM DTCs.
    6. Start the engine and allow it to idle for 5 minutes.
    7. With the scan tool, read BSCM DTCs.

      Did the DTC return?

      Yes 

      • Go To  2

      No 

  2. CHECK THE F29 (40A) FUSE 
    1. Turn the ignition on.
    2. With a 12-volt test light connected to ground, check the F29 (40A) Fuse for power.

    Does the test light illuminate brightly?

    Yes 

    • Go To  3

    No 

    • If the related fuse is open, check the circuit for a short to ground
    • Perform the BSCM VERIFICATION TEST. Refer to BSCM VERIFICATION TEST .
  3. CHECK THE (A200) FUSED (B+) CIRCUIT FOR HIGH RESISTANCE BY LOAD TESTING THE CIRCUIT 
    1. Disconnect the harness connector to isolate the 12.0 volt supply circuit.
    2. Connect the positive lead of the load test tool to the 12.0 volt supply circuit at the BSCM harness connector (A). Note:  refer to the diagram below.
    3. Connect the negative lead of the load test tool to the ground circuit of the Battery or a good chassis ground.
    4. Make sure that the circuit being tested is being powered on. If the 12.0 volt circuit being tested is an ignition feed for example, the ignition must be on. If testing an output from a relay, verify that the relay is energized and on.
    5. The bulb on the load test tool should be illuminated and bright if there is no resistance in the circuitry.
    NOTE:

    Why load test a circuit?  A load test is used to determine if a circuit is capable of carrying the amperage needed to perform properly. The 3156 bulb in the load tool illustrated, is a simple but effective method of testing circuit functionality. A 3156 Bulb has approximately 6.0 Ohms of resistance when the bulb is powered  and draws approximately 2.0 amps of current. Read the CIRCUIT LOAD TESTING PROCEDURE for information on building a simple load test tool and for additional load testing information and alternative methods of load testing or voltage drop testing a circuit. Refer to CIRCUIT LOAD TESTING PROCEDURES .

    NOTE:

    A 12-volt test light can be substituted for the load test tool, but only  if the test light draws enough current to effectively load test the circuit. Many high impedance test lights draw very little amperage (less than 0.1 amps) and are not reliable to load test a circuit. To perform a proper load test of a circuit, the tool being used should draw more than approximately 0.75 amps.

    NOTE:

    Why perform a Voltage Drop Test?  To verify with certainty there is not any resistance in the circuit being tested, perform a simple voltage drop test across the 3156 bulb of the load test tool. To do so perform the following:

    • 1. Connect the leads of a DVOM to the alligator clips on the load test tool while the load test tool is connected in series with the circuit.
    • 2. Compare the voltage drop across the bulb to the voltage reading across the Battery terminals.
    • 3. The voltage dropped across the bulb should be equal to the voltage reading across the Battery terminals if there is no resistance in the circuit being tested.

    Example:  2.0 Ohms of resistance in the circuit being tested will cause the voltage measurement across the bulb to be 25% less than when compared to Battery voltage. The reason for this is that the 2.0 Ohms in the circuit makes up 25% of the total circuit resistance of 8.0 Ohms. Read the CIRCUIT LOAD TESTING PROCEDURE for information on building a simple load test tool and for additional load testing information and alternative methods of load testing or voltage drop testing a circuit. Refer to CIRCUIT LOAD TESTING PROCEDURES .

    GC0174938Courtesy of CHRYSLER GROUP, LLC
    NOTE:

    When probing a circuit at an Electronic Control Unit (ECU) harness connector, always use an appropriate back probing tool to prevent any possible damage to the ECU terminals.

    NOTE:

    Compare the brightness of the bulb in the load test tool to that of a direct connection to Battery.

    Is the load test bulb illuminated and bright?

    Yes 

    • Go To  4

    No 

    • Repair the 12.0 volt circuit for an open or high resistance.
    • Perform the BSCM VERIFICATION TEST. Refer to BSCM VERIFICATION TEST .
  4. CHECK THE (Z933) GROUND CIRCUIT FOR HIGH RESISTANCE BY LOAD TESTING THE CIRCUIT 
    1. Disconnect the BSCM harness connector to isolate the ground circuit.
    2. Connect the positive lead of the load test tool to the positive side of the Battery.
    3. Connect the negative lead of the load test tool to the (Z933) ground circuit at the component harness connector (A). Note:  refer to the diagram below.
    4. The bulb on the load test tool should be illuminated and bright if there is no resistance in the circuitry.
    NOTE:

    Why load test a circuit?  A load test is used to determine if a circuit is capable of carrying the amperage needed to perform properly. The 3156 bulb in the load tool illustrated, is a simple but effective method of testing circuit functionality. A 3156 Bulb has approximately 6.0 Ohms of resistance when the bulb is powered  and draws approximately 2.0 amps of current. Read the CIRCUIT LOAD TESTING PROCEDURE for information on building a simple load test tool and for additional load testing information and alternative methods of load testing or voltage drop testing a circuit. Refer to CIRCUIT LOAD TESTING PROCEDURES .

    NOTE:

    A 12-volt test light can be substituted for the load test tool, but only  if the test light draws enough current to effectively load test the circuit. Many high impedance test lights draw very little amperage (less than 0.1 amps) and are not reliable to load test a circuit. To perform a proper load test of a circuit, the tool being used should draw more than approximately 0.75 amps.

    NOTE:

    Why perform a Voltage Drop Test:  To verify with certainty there is not any resistance in the circuit being tested, perform a simple voltage drop test across the 3156 bulb of the load test tool. To do so perform the following:

    • 1. Connect the leads of a DVOM to the alligator clips on the load test tool while the load test tool is connected in series with the circuit.
    • 2. Compare the voltage drop across the bulb to the voltage reading across the Battery terminals.
    • 3. The voltage dropped across the bulb should be equal to the voltage reading across the Battery terminals if there is no resistance in the circuit being tested.

    Example:  2.0 Ohms of resistance in the circuit being tested will cause the voltage measurement across the bulb to be 25% less than when compared to Battery voltage. The reason for this is that the 2.0 Ohms in the circuit makes up 25% of the total circuit resistance of 8.0 Ohms. Read the CIRCUIT LOAD TESTING PROCEDURE for information on building a simple load test tool and for additional load testing information and alternative methods of load testing or voltage drop testing a circuit. Refer to CIRCUIT LOAD TESTING PROCEDURES

    GC0174957Courtesy of CHRYSLER GROUP, LLC
    NOTE:

    When probing a circuit at an Electronic Control Unit (ECU) harness connector, always use an appropriate back probing tool to prevent any possible damage to the ECU terminals.

    NOTE:

    Compare the brightness of the bulb in the load test tool to that of a direct connection to Battery.

    Is the load test bulb illuminated and bright?

    Yes 

    • Go To  5

    No 

    • Repair the (Z933) ground circuit for an open or high resistance.
    • Perform the BSCM VERIFICATION TEST. Refer to BSCM VERIFICATION TEST .
  5. CHECK RELATED HARNESS CONNECTIONS 
    1. Turn the ignition off.
    2. Disconnect the BSCM harness connector.
    3. Disconnect all related in-line harness connections (if equipped).
    4. Disconnect the related component harness connectors.
    5. Inspect harness connectors, component connectors, and all male and female terminals for the following conditions:
      • Proper connector installation.
      • Damaged connector locks.
      • Corrosion.
      • Other signs of water intrusion.
      • Weather seal damage (if equipped).
      • Bent terminals.
      • Overheating due to a poor connection (terminal may be discolored due to excessive current draw).
      • Terminals that have been pushed back into the connector cavity.
      • Perform a terminal drag test on each connector terminal to verify proper terminal tension.

      Repair any conditions that are found.

    6. Connect the BSCM harness connector. Be certain that the harness connector is fully seated and the connector lock is fully engaged.
    7. Connect all in-line harness connectors (if equipped). Be certain that all connectors are fully seated and the connector locks are fully engaged.
    8. Connect the related component harness connectors. Be certain that all connectors are fully seated and the connector locks are fully engaged.
    9. With the scan tool, erase DTCs.
      WARNING:

      To avoid possible serious or fatal injury, check brake capability is available before road testing.

    10. Using the recorded Event and Environmental Data, along with the When Monitored and Set Conditions above, operate the vehicle in the conditions that set the DTC.
    11. With the scan tool, read BSCM DTCs.

      Did the DTC return?

      Yes 

      No 

      • The wiring or poor connection problem has been repaired.
      • Perform the BSCM VERIFICATION TEST. Refer to BSCM VERIFICATION TEST .
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