DTC U1500-U15FF

Diagnostic Instructions

DTC Descriptor

For device DTC descriptors, refer to Control Module U Code List.

Diagnostic Fault Information

Circuit

Short to Ground

Open/High Resistance

Short to Voltage

Signal Performance

B+

U1500-U15BF

U1500-U15BF

—

—

Ignition

U1500-U15BF

U1500-U15BF

—

—

LIN Serial Data

U1500-U15BF

U1500-U15BF

U1500-U15BF

—

Ground

—

U1500-U15BF

—

—

Circuit/System Description

The Local Interconnect Network (LIN) Bus consists of a single wire with a transmission rate of 10.417 Kbit/s. The serial data is transmitted over a LIN circuit between a master control module and other LIN devices within a particular subsystem. If serial data communication is lost between any of the LIN devices on the LIN bus network, the master control module will set a no communication code against the non-communicating LIN device.

Conditions for Running the DTC

The system voltage is between 9-16 V.

Conditions for Setting the DTC

A supervised periodic message that includes the transmitter device availability has not been received.

Action Taken When the DTC Sets

Specific subsystems will not function.

Conditions for Clearing the DTC

  • A current DTC clears when the malfunction is no longer present.
  • A history DTC clears when the device ignition cycle counter reaches the reset threshold of 50, without a repeat of the malfunction.

Diagnostic Aids

  • Sometimes, while diagnosing a specific customer concern or after a repair, you may notice a history U code present. However, there is no associated “current” or “active” status. Loss of communication U codes such as these can set for a variety of reasons. Many times, they are transparent to the vehicle operator and technician, and/or have no associated symptoms. Eventually, they will erase themselves automatically after a number of fault-free ignition cycles. This condition would most likely be attributed to one of these scenarios:
    • A device on the data communication circuit was disconnected while the communication circuit is awake.
    • Power to one or more devices was interrupted during diagnosis.
    • A low battery condition was present, so some devices stop communicating when battery voltage drops below a certain threshold.
    • Battery power was restored to the vehicle and devices on the communication circuit did not all re-initialize at the same time.
    • If a loss of communication U code appears in history for no apparent reason, it is most likely associated with one of the scenarios above. These are all temporary conditions and should never be interpreted as an intermittent fault, causing you to replace a part.
  • A device may have a U code stored in history that does not require any repairs. Issues with late or corrupted messages between devices can be temporary with no apparent symptom or complaint; this does not mean the device is faulty. Do not replace a device based only on a history U code.
  • Do not replace a device reporting a U code. The U code identifies which device needs to be diagnosed for a communication issue.
  • Communication will be available between the master control module and the scan tool if there is a loss of communications with any of the other LIN devices on the LIN bus network.
  • Some devices may not have internal protection for specific control circuits and may open a B+ or ignition fuse. If a fuse is open and the B+ or ignition circuit is not shorted to ground, ensure none of the control circuits are shorted to ground before replacing the device.
  • Some intermittent communication concerns may be caused by fretting corrosion on the serial data circuit terminals. Inspect all connectors at the device that set the communication DTC, the device that the communication DTC was set against, and any inline harness connectors between the two devices. Do not replace a device based only on fretting corrosion. Refer to bulletin 09-06-03-004 for assistance with the diagnosis and repair of this condition, if applicable.
  • An open in the LIN bus serial data circuit between the splice pack and a LIN device will only affect that specific LIN device. This type of failure will set a loss of communication DTC for each LIN device affected and the other LIN devices will still communicate.
  • This diagnostic procedure can be used to diagnose the common LIN DTCs: U1500, U1501, U1502, U1503, U1504, U1505, U1506, U1507, U1508, U1509, U150E, U150F, U1510, U1511, U1512, U1513, U1514, U1515, U1516, U1517, U1518, U1519, U151A, U151B, U151C, U1520, U1521, U1522, U1523, U1524, U1526, U1528, U152C, U152D, U1530, U1531, U1532, U1534, U1538, U153A, U1540, U1544, U1548, U1549, U154A, U154B, U1550, U1556, U1558, U15E1, U15E3, U15F0, and other DTCs within the U1500–U15FF range.

Reference Information

Schematic ReferenceConnector End View Reference

Master Electrical Component List

Description and Operation

Data Link Communications Description and Operation

Electrical Information ReferenceScan Tool Reference

Control Module References for scan tool information

Circuit/System Verification

Note: For vehicles not equipped with K29 Seat Heating Control Module, K29F Seat Heating Control Module - Front, K29R Seat Heating Control Module - Rear, or K32 Steering Wheel Heating Control Module:

  • Ignore DTC U1524 if equipped with RPO 00V
  • Ignore DTC U1526 if equipped with RPO 00R
  • Ignore DTC U152B if equipped with RPO 00G

  1. Determine the LIN device that is not communicating. Refer to Control Module U Code List.
  2. Ignition ON/Vehicle In Service Mode.
  3. Verify that DTC B1325, B1330, B1370, B1380, B1424, B1440, B1441, B1517, C0800, C0899, C12E1, P0560, P0562, P06E4, U0028, U0029, U0073-U0078, U007A-U007D, U0100-U02FF, U1814, U2098, or U2099 is not set.
    • If none of the DTCs are set
  4. Refer to Circuit/System Testing.

Circuit/System Testing

Note:

  • A DTC in U1501-U150F range is normally used to indicate a LIN bus off. If a DTC in U1501-U150F range is set by itself, use the LIN schematics for the device setting this DTC to identify the LIN slave device to diagnose it.
  • For some vehicles, both headlamps may be connected to the same LIN circuit through a splice. Or both LIN circuits to the headlamps may be internally connected at the connector of the K26 Headlamp Control Module (or K28 Headlamp Leveling Control Module). A short in one headlamp or its LIN circuit may cause no communication to both headlamps. Ensure to diagnose both LIN circuits and headlamps prior to replacing any headlamp.
  • Use the schematic to identify the following:
    • The master control module and the LIN devices on the same LIN serial data circuit
    • The master control module's LIN serial data circuit terminal and the LIN device's B+, ignition, ground, and LIN serial data circuit terminals

  1. Ignition/Vehicle OFF, all access doors closed, all vehicle systems OFF, and all keys at least 3 m (9.8 ft) away from vehicle. Disconnect the harness connectors at a LIN device that is not communicating. It may take up to 10 min for all vehicle systems to power down.
  2. Test for less than 10 Ω between each ground circuit terminal and ground.
    • If 10 Ω or greater
    1. Ignition/Vehicle OFF.
    2. Test for less than 2 Ω in the ground circuit end to end.
      • If 2 Ω or greater, repair the open/high resistance in the circuit.
      • If less than 2 Ω, repair the open/high resistance in the ground connection.
    • If less than 10 Ω
  3. Ignition ON/Vehicle In Service Mode.
  4. If equipped, verify a test lamp illuminates between each B+ circuit terminal and ground.
    • If the test lamp does not illuminate and the circuit fuse is good
    1. Ignition/Vehicle OFF, remove the test lamp.
    2. Test for less than 2 Ω in the B+ circuit end to end.
      • If 2 Ω or greater, repair the open/high resistance in the circuit.
      • If less than 2 Ω, verify the fuse is not open and there is voltage at the fuse.
    • If the test lamp does not illuminate and the circuit fuse is open
    1. Ignition/Vehicle OFF, remove the test lamp.
    2. Test for infinite resistance between the B+ circuit and ground.
      • If less than infinite resistance, repair the short to ground in the circuit.
      • If infinite resistance, replace the disconnected LIN device.
    • If the test lamp illuminates
  5. If equipped, verify a test lamp illuminates between each ignition circuit terminal and ground.
    • If the test lamp does not illuminate and the circuit fuse is good
    1. Ignition/Vehicle OFF, remove the test lamp.
    2. Test for less than 2 Ω in the ignition circuit end to end.
      • If 2 Ω or greater, repair the open/high resistance in the circuit.
      • If less than 2 Ω, verify the fuse is OK and there is voltage at the fuse.
    • If the test lamp does not illuminate and the circuit fuse is open
    1. Ignition/Vehicle OFF, remove the test lamp.
    2. Test for infinite resistance between the ignition circuit and ground.
      • If less than infinite resistance, repair the short to ground in the circuit.
      • If infinite resistance, replace the disconnected LIN device.
    • If the test lamp illuminates
  6. If equipped, verify a test lamp illuminates between each ignition circuit terminal, which is controlled by a control module, and ground.
    • If the test lamp does not illuminate
    1. Ignition/Vehicle OFF, remove the test lamp, disconnect the harness connectors at the control module that controls the ignition circuit and all devices that share the same ignition circuit.
    2. Test for infinite resistance between the ignition circuit terminal and ground.
      • If less than infinite resistance, repair the short to ground in the circuit.
      • If infinite resistance
    3. Test for less than 2 Ω in the ignition circuit end to end.
      • If 2 Ω or greater, repair the open/high resistance in the circuit.
      • If less than 2 Ω
    4. Reconnect the control module that controls the ignition circuit.
    5. Ignition ON/Vehicle In Service Mode.
    6. Verify a test lamp illuminates between the ignition circuit terminal and ground.
      • If the test lamp does not illuminate, replace the control module that controls the ignition circuit.
      • If the test lamp illuminates
    7. Ignition/Vehicle OFF, reconnect the first device that shares the same ignition circuit.
    8. Ignition ON/Vehicle In Service Mode.
    9. Verify a test lamp illuminates between the ignition circuit terminal and ground.
      • If the test lamp does not illuminate, replace the device that was just connected.
      • If the test lamp illuminates and there are more devices to connect, connect the next device and repeat step 6.9 until there are no more devices to connect.
    • If the test lamp illuminates
  7. Ignition/Vehicle OFF, disconnect all LIN devices that share the same LIN serial data circuit.
  8. Ignition ON/Vehicle In Service Mode.

    9. Note: For accurate voltage reading, disconnect the battery charger prior to performing the following test step.

  9. Test for 3.5-12 V between the LIN serial data circuit terminal and ground.
    • If less than 3.5 V
    1. Ignition/Vehicle OFF, disconnect the harness connectors at the control module setting the DTC.
    2. Test for infinite resistance between the LIN serial data circuit terminal and ground.
      • If less than infinite resistance, repair the short to ground in the circuit.
      • If infinite resistance
    3. Test for less than 2 Ω in the LIN serial data circuit end to end.
      • If 2 Ω or greater, repair the open/high resistance in the circuit.
      • If less than 2 Ω
    4. Replace the control module that sets the DTC.
    • If greater than 12 V
    1. Ignition/Vehicle OFF, disconnect the harness connectors at the control module setting the DTC.
    2. Ignition ON/Vehicle In Service Mode.
    3. Test for less than 1 V between the LIN serial data circuit terminal and ground.
      • If 1 V or greater, repair the short to voltage in the circuit.
      • If less than 1 V
    4. Replace the control module that sets the DTC.
    • If between 3.5-12 V
  10. Verify how many LIN devices are connected to this LIN circuit.
    • If there is only one LIN device
    1. Ignition/Vehicle OFF, inspect both harness and component connectors for contamination, corrosion, and terminal tension.
    2. Reconnect the harness connectors at the LIN device. Verify all connectors/terminals are fully seated.
    3. Ignition ON/Vehicle In Service Mode.
    4. Verify the DTC is not set again.
      • If the DTC is set, replace the LIN device that is not communicating.
      • If the DTC is not set
    5. A fault is currently not present and may be an intermittent condition.
    • If there are two or more LIN devices
  11. Ignition/Vehicle OFF, disconnect the harness connectors at the control module setting the DTC.
  12. Reconnect the harness connectors at the first LIN device.
  13. Ignition ON/Vehicle In Service Mode.
  14. Test for 3.5-12 V between the LIN serial data circuit terminal at the control module setting the DTC and ground.
    • If less than 3.5 V or greater than 12 V

      Replace the LIN device that was just connected.

    • If between 3.5-12 V
  15. Ignition/Vehicle OFF, reconnect the harness connectors at another LIN device.
  16. Ignition ON/Vehicle In Service Mode.
  17. Test for 3.5-12 V between the LIN serial data circuit terminal at the control module setting the DTC and ground.
    • If less than 3.5 V or greater than 12 V

      Replace the LIN device that was just connected.

    • If between 3.5-12 V
  18. Repeat steps 15-17 for the remaining LIN devices until a faulty LIN device is identified. If there is no faulty LIN device, replace the LIN device that is not communicating.

Repair Instructions

Perform the Diagnostic Repair Verification after completing the repair.

Control Module References for device replacement, programming and setup