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Tahoe / Yukon Service Manual

DTC U1604 or U1605

Diagnostic Instructions Perform the Diagnostic System Check - Vehicle prior to using this diagnostic procedure. Review Strategy Based Diagnosis for an overview of the diagnostic approach. Diagnostic Procedure Instructions provides an overview of each diagnostic category. DTC Descriptors DTC U1604 Lost Communication with Side Obstacle Detection Control Module - Left on Private CAN Bus DTC U1605 Lost Communication with Side Obstacle Detection Control Module - Right on Private CAN Bus For symptom byte information, refer to Symptom Byte List. Diagnostic Fault Information

Circuit Number Circuit Function Short to Ground Open/High Resistance Short to Voltage Signal Performan
4087 Serial Data U1604, U1605 U1604, U1605 U1604, U1605 —
4088 Serial Data U1604, U1605 U1604, U1605 U1604, U1605 —

Circuit/System Description The side blind zone alert system helps alert drivers to avoid changing lanes when vehicles are detected in the side blind zone of the adjacent lane. The side blind zone alert system utilized two controls modules, the B218L Side Obstacle Detection Control Module – Left and the B218R Side Obstacle Detection Control Module – Right. Each B218  Side Obstacle Detection Control Module contains a radar and is located at the rear corner of the vehicle, behind the fasica. The B218L Side Obstacle Detection Control Module – Left and the B218R Side Obstacle Detection Control Module – Right communicate with one another on a private CAN bus and with the rest of the vehicle on CAN bus 4. Conditions for Running the DTC Ignition ON Conditions for Setting the DTC U1604 The B218R Side Obstacle Detection Control Module – Right has lost communication with the B218L Side Obstacle Detection Control Module – Left on their private CAN bus. U1605 The B218L Side Obstacle Detection Control Module – Left has lost communication with the B218R  Side Obstacle Detection Control Module – Right on their private CAN bus. Action Taken When the DTC Sets The side blind zone alert system is disabled. Conditions for Clearing the DTC The condition for setting the DTC is no longer present. Reference Information Schematic Reference Driver Assistance Systems Schematics Connector End View Reference Master Electrical Component List Description and Operation Side Blind Zone Alert Description and Operation Electrical Information Reference Circuit Testing Connector Repairs Testing for Intermittent Conditions and Poor Connections Wiring Repairs Scan Tool Reference Control Module References for scan tool information Circuit/System Testing

  1. Ignition OFF, disconnect the connector at the B218L Side Obstacle Detection Control Module – Left and the B218R Side Obstacle Detection Control Module – Right, ignition ON.
  2. Test for less than 1 V between serial data circuit terminal 1 and ground. ⇒ If 1 V or greater Repair the short to voltage on circuit 4087. ⇓ If less than 1 V
  3. Test for less than 1 V between serial data circuit terminal 2 and ground. ⇒ If 1 V or greater Repair the short to voltage on circuit 4087. ⇓ If less than 1 V
  4. Ignition OFF.
  5. Test for infinite resistance between serial data circuit terminal 1 and ground. ⇒ If less than infinite resistance Repair the short to ground on circuit 4087. ⇓ If infinite resistance
  6. Test for infinite resistance between serial data circuit terminal 2 and ground. ⇒ If less than infinite resistance Repair the short to ground on circuit 4088. ⇓ If infinite resistance
  7. Test for less than 2 Ω between terminal 1 at the B218L Side Obstacle Detection Control Module – Left and terminal 1 at the B218R Side Obstacle Detection Control Module – Right. ⇒ If 2 Ω or greater Repair the open/high resistance on circuit 4087. ⇓ If less than 2 Ω
  8. Test for less than 2 Ω between terminal 2 at the B218L Side Obstacle Detection Control Module – Left and terminal 2 at the B218R Side Obstacle Detection Control Module – Right. ⇒ If 2 Ω or greater Repair the open/high resistance on circuit 4087. ⇓ If less than 2 Ω
  9. Connect the connector at the B218L Side Obstacle Detection Control Module – Left and the B218R Side Obstacle Detection Control Module – Right, ignition ON.
  10. Clear DTCs.
  11. Operate the vehicle within the Conditions for Running the DTC.
  12. Verify DTC U1604 or U1605 is not set. ⇒ If DTC U1604 is set Replace the B218L Side Obstacle Detection Control Module – Left . ⇒ If DTC U1605 is set Replace the B218R Side Obstacle Detection Control Module – Right. ⇓ If DTC U1604 or U1605 is not set
  13. A fault is currently not present and may be an intermittent condition. Repair Instructions Perform the Diagnostic Repair Verification after completing the repair. Control Module References for control module replacement, programming, and setup.