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Home >> Jeep >> 2022 >> Cherokee Trailhawk >> Repair and Diagnosis >> Brakes >> Anti-Lock Brakes >> Antilock Brake System (Abs) - DTCS C2200-44 To U140E-00 >> Diagnosis And Testing >> U0401-00-Implausible Data Received From ECM/Pcm >> Diagnostic Test

Diagnostic Test

  1. CHECK FOR AN ACTIVE DTC 
    NOTE:

    This DTC must be active for the results of this test to be valid.

    1. Perform any Service Bulletins that may apply.
    2. Turn the ignition on.
    3. With the scan tool, read ABS DTCs and record on the repair order.
    4. Cycle the ignition switch from off to on.
    5. With the scan tool, read ABS DTCs.

      Is the DTC active?

      Yes 

      • Go To  2

      No 

  2. CHECK FOR POWERTRAIN CONTROL MODULE (PCM) OR COMMUNICATION RELATED DTCS 
    1. Refer to the recorded DTCs.

      Are there any PCM DTCs present?

      Yes 

      • Perform the applicable diagnostic procedure(s). Refer to the appropriate diagnostic information .

      No 

      • Go To  3
  3. PERFORM THE ELECTRIC VACUUM PUMP ACTUATION 
    1. Turn the ignition on, engine not running.
    2. With the scan tool actuate the Electronic Vacuum Pump.

      Does the Electric Vacuum Pump run?

      Yes 

      • Go To  9

      No 

      • Go To  4
  4. CHECK THE (T108) ELECTRIC VACUUM PUMP OUTPUT CIRCUIT FOR VOLTAGE 
    1. Disconnect the Electric Vacuum Pump (EVP) harness connector.
    2. With the scan tool actuate the Electronic Vacuum Pump.
    3. Using a 12-volt test light connected to ground, probe the (T108) Electric Vacuum Pump Output circuit at the EVP harness connector.

      Does the test light illuminate brightly?

      Yes 

      • Go To  5

      No 

      • Go To  6
  5. CHECK THE EVP GROUND CIRCUIT FOR AN OPEN/HIGH RESISTANCE 
    1. Using a 12-volt test light connected to 12 volts, probe the EVP Ground circuit at the EVP harness connector.

      Does the test light illuminate brightly?

      Yes 

      • Replace the Electric Vacuum Pump in accordance with the Service Information.
      • Perform ABS VERIFICATION TEST. Refer to ABS VERIFICATION TEST .

      No 

      • Repair the EVP Ground circuit for an open or high resistance.

        Perform the POWERTRAIN VERIFICATION TEST. Refer to the appropriate information. .

  6. CHECK THE (T108) ELECTRIC VACUUM PUMP OUTPUT CIRCUIT FOR AN OPEN/HIGH RESISTANCE 
    1. Turn the ignition off.
    2. Remove the EVP Relay from the PDC.
    3. Measure the resistance of the (T108) Electric Vacuum Pump Output circuit between the EVP Relay connector and the EVP harness connector.

      Is the resistance below 3.0 Ohms?

      Yes 

      • Go To  7

      No 

      • Repair the (T108) Electric Vacuum Pump Output circuit for an open or high resistance.
      • Perform ABS VERIFICATION TEST. Refer to ABS VERIFICATION TEST .
  7. CHECK THE (T108) ELECTRIC VACUUM PUMP OUTPUT CIRCUIT FOR A SHORT TO GROUND 
    1. Check for continuity between ground and the (T108) Electric Vacuum Pump Output circuit at the EVP Relay connector.

      Is there continuity between ground and the (T108) Electric Vacuum Pump Output circuit?

      Yes 

      • Repair the (T108) Electric Vacuum Pump Output circuit for a short to ground. If the circuit was shorted to ground, test the Fuses in the PDC and replace if necessary.
      • Perform ABS VERIFICATION TEST. Refer to ABS VERIFICATION TEST .

      No 

      • Go To  8
  8. CHECK THE FUSED B+ CIRCUIT AT THE EVP RELAY FOR AN OPEN/HIGH RESISTANCE IN THE PDC 
    1. Turn the ignition on.
    2. Using a 12-volt test light connected to ground, probe the Fused B+ circuit at the EVP Relay connector (terminal 30).

      Does the test light illuminate brightly?

      Yes 

      • Replace the Vacuum Pump Relay. With the scan tool actuate the Electronic Vacuum Pump. Using a 12-volt test light connected to ground, probe the (T108) Electric Vacuum Pump Output circuit at the Electric Vacuum Pump harness connector. If the test light still does not illuminate brightly, replace the PDC in accordance with the Service Information.
      • Perform ABS VERIFICATION TEST. Refer to ABS VERIFICATION TEST .

      No 

      • Check all of the fuses in the PDC. If the fuses are not blown, replace the PDC in accordance with the Service Information.
      • Perform ABS VERIFICATION TEST. Refer to ABS VERIFICATION TEST .
  9. CHECK THE VACUUM SUPPLY FOR PINCHED LINES OR OTHER DAMAGE 
    1. Turn the ignition off.
    2. Check the vacuum supply line to brake booster for a pinched, cut or open hose.
    3. Check all vacuum lines, check valves, etc. for the Electric Vacuum Pump system for a pinched, cracked, cut or open hose

      Were any problems found?

      Yes 

      No 

      • Go To  10
  10. REPLACE THE ANTI-LOCK BRAKE SYSTEM (ABS) MODULE AND TEST FOR DTCS 
    1. Disconnect the ABS harness connector.
    2. Disconnect all related in-line harness connections (if equipped).
    3. Disconnect the related component harness connectors.
    4. 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. If no problems were found, Replace the Anti-lock Brake System (ABS) Module in accordance with the Service Information. Refer to MODULE, ANTI-LOCK BRAKE SYSTEM (ABS), REMOVAL .

    5. Perform the ABS VERIFICATION TEST. Refer to ABS VERIFICATION TEST .
    6. With the scan tool, erase ABS DTCs.
      WARNING:

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

    7. Test drive the vehicle at speeds above 40 k/mh (25 mph).
    8. With the scan tool, read ABS DTCs.

      Did the DTC return?

      Yes 

      • Go To  11

      No 

      • Test complete.
  11. CHECK RELATED HARNESS CONNECTIONS 
    1. Turn the ignition off.
    2. Disconnect the Powertrain Control Module (PCM) harness connectors.
    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 PCM harness connectors. Be certain that the harness connectors are 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 personal injury or death, 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 ABS Module DTCs.

      Did the DTC return?

      Yes 

      • Replace the Powertrain Control Module (PCM) in accordance with the Service Information. Refer to MODULE, POWERTRAIN CONTROL (PCM), REMOVAL .
      • Perform PCM VERIFICATION TEST. Refer to the appropriate information. .

      No 

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