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Home >> Jeep >> 2025 >> Grand Cherokee Altitude, AWD >> Repair and Diagnosis >> Accessories & Equipment >> Entertainment Systems >> Audio (Radio) - DTCS B157A-13 To B2204-00 >> DTC Troubleshooting >> B15A2-00 Port 2 Connection >> Diagnostic Test

Diagnostic Test

  1. READ AND RECORD DTCS AND ENVIRONMENTAL DATA - ERASE DTCS AND CHECK FOR DTC TO RETURN 
    1. With the scan tool, read DTCs in all Electronic Control Units (ECUs) and record on the repair order.
    2. With the scan tool, run a vehicle Scan Report, or record the Environmental Data related to the DTCs.
    3. With the scan tool, perform an ECU reset to the Radio and AMP (if equipped), and then erase DTCs.
    4. Turn the ignition off for a minimum of 10.0 seconds.
    5. Turn the ignition on.
    6. Using the recorded Environmental Data and the When Monitored Conditions above, operate the vehicle in the conditions that set the DTC.
    7. With the scan tool, read DTCs.
      NOTE:

      The Radio must be on and a front door must remain open whenever checking or erasing Radio DTCs. 

      Did the DTC return?

      Yes 

      • Go To Next Step.

      No 

  2. CHECK THE RELATED FUSED B+ CIRCUIT FOR HIGH RESISTANCE BY LOAD TESTING THE CIRCUIT 
    1. Disconnect the component 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 component 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. Ensure 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 .

      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. 

      GC0174938Courtesy of CHRYSLER GROUP, LLC

      Is the load test bulb illuminated and bright?

      Yes 

      • Go To  4.

      No 

      • Check the related fuse for an open.
      • If the circuit is open due to a open fuse, Go To Next Step.
      • If the fuse is not open, repair the 12.0 volt circuit for an open or high resistance.
      • Perform the BODY VERIFICATION TEST. Refer to BODY VERIFICATION TEST .
  3. ISOLATE AND CHECK THE RELATED FUSED B+ CIRCUIT FOR A SHORT TO GROUND 
    1. The ignition must be off when checking a circuit for continuity to ground.
    2. Isolate the circuit by disconnecting the Electronic Control Unit (ECU) and every component harness connector containing the circuit being tested. Note:  Use the wiring diagram as a guide to follow the path of the circuit.
    3. Connect the negative lead of the DVOM to a known good ground.
    4. With the positive lead of the DVOM, probe the circuit being tested at the component harness connector and check for continuity between the circuit and ground.
      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:

      There should be no continuity between ground and the circuit being tested. 

      Is there continuity between ground and the circuit being tested?

      Yes 

      • Repair the circuit for a short to ground. Use the wiring diagram as a guide to trace the circuit and look for any in-line connectors to help isolate the location of the short.
      • Perform the BODY VERIFICATION TEST. Refer to BODY VERIFICATION TEST .

      No 

      • Refer to  5.
  4. CHECK THE RELATED GROUND CIRCUIT FOR OPEN OR HIGH RESISTANCE BY LOAD TESTING THE CIRCUIT 
    1. Isolate the ground circuit(s).
    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 ground circuit at the ECU 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 .

      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. 

      GC0174957Courtesy of CHRYSLER GROUP, LLC

      Is the load test bulb illuminated and bright?

      Yes 

      • Go To Next Step.

      No 

      • Repair the ground circuit(s) for an open or high resistance.
      • Perform the BODY VERIFICATION TEST. Refer to BODY VERIFICATION TEST .
  5. CHECK THE CONNECTORS AND HARNESS 
    NOTE: This test is designed to validate the ability of the Audio/Media system to play audio from a customer's device that has been connected to the USB port on the radio or the external USB port (Universal Customer Interface (UCI) / Multi- Media port). By connecting a known good compatible device to the USB ports it will also determine if the USB port can provide power to a connected device.
    It is important to determine the system features supported by the vehicle's multi-media systems, customer's personal device and their compatibility with another.
    For device compatibility, refer to http://www.driveuconnect.com
    Prior to performing any testing of the multi-media systems, the compatibility between the customer's personal device and the vehicle's multi-media systems must be confirmed.
    1. Confirm the USB port is not a Charge only  port.
    2. Turn the ignition off.
    3. Disconnect the USB harness connector at the back of the radio.
    4. Disconnect the USB harness connector at the Media Port.
    5. Inspect the connectors and harness between the USB Media Port and the radio.

      Are there any issues with the harness or connectors?

      Yes 

      No 

      • Go To Next Step.
  6. CHECK THE USB CABLE 
    1. Connect the Radio Diagnostic Tool to the Media Port connection on the back of the Radio and to the Media Port.

      (special tool #9977-6-15, 12-Way to two 5-Way USB R1 Radio Test Cable)

    2. Make sure one of the front doors is still open.
    3. Turn the ignition on.
    4. With the scan tool, perform an ECU reset to the Radio, and then erase DTCs.
    5. Turn the Radio on.
    6. Using the scan tool, read Radio DTCs.

      Is the DTC active?

      Yes 

      • Go To Next Step.

      No 

  7. CHECK THE MEDIA PORT 
    NOTE: This test is designed to validate the ability of the Audio/Media system to play audio from a customer's device that has been connected to the USB port on the radio or the external USB port (Universal Customer Interface (UCI) / Multi- Media port). By connecting a known good compatible device to the USB ports it will also determine if the USB port can provide power to a connected device.
    It is important to determine the system features supported by the vehicle's multi-media systems, customer's personal device and their compatibility with another.
    For device compatibility, refer to http://www.driveuconnect.com
    Prior to performing any testing of the multi-media systems, the compatibility between the customer's personal device and the vehicle's multi-media systems must be confirmed.
    1. Confirm the USB port is not a Charge only  port.
    2. Using a known good USB Cable, connect the USB Cable to the vehicle's USB port.
    3. Connect the USB Cable to the known good compatible device.
    4. Select and audio file from the known good compatible device to be heard with the volume all the way up.
    5. Using the vehicle controls, place the audio system into USB Mode. (Audio system may automatically enter into USB Mode.)

      Does the Radio play audio from the known good compatible device?

      Yes 

      No 

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