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Tahoe / Yukon Service Manual

DTC B1451

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 Passive Entry Rear Closure Antenna Signal Hi For symptom byte information, refer to Symptom Byte List. Diagnostic Fault Information

Circuit Number Circuit Short to Ground Open/Hi Resistan Short gh to ceVoltage Signal Performa
3568 Passive Entry Rear Closure Antenna Signal Hi — High Reference B1451 11 B1451 13 B1451 12 —
3569 Passive Entry Rear Closure Antenna Signal Hi — Low Reference B1451 11 B1451 13 B1451 12 —

Circuit/System Description The antenna is located behind the rear fascia and is used to establish low frequency communications with the keyless entry transmitter. As a vehicle with locked doors is approached with a keyless entry transmitter and the trunk touch pad is pressed, the body control module communicates with the keyless entry antenna. Diagnostic Aids The antenna must be installed correctly for proper performance. The precise location and orientation are important for the antenna to have the range and shape of range designed for each antenna location. There is a possibility that the passive entry system set a false DTC due to the antenna being incorrectly installed. Conditions for Running the DTC The trunk touch pad is pressed or all the doors are closed. Conditions for Setting the DTC B1451 11 The body control module detects a short to ground on the passive entry rear closure antenna signal circuit three or more times. B1451 12 The body control module detects a short to voltage on the passive entry rear closure antenna signal circuit three or more times. B1451 13 The body control module detects an open on the passive entry rear closure antenna circuit three or more times. Action Taken When the DTC Sets Rear closure will not open when the trunk touch pad is pressed if the vehicle is locked. Reduced or no coverage of the keyless entry transmitter outside the vehicle when the trunk touch pad is pressed. The service keyless start system message will display in the DIC. Conditions for Clearing the DTC A current DTC will clear when the conditions for setting the DTC are no longer present. A history DTC will clear after 50 malfunction-free ignition cycles. Reference Information Schematic Reference Remote Function Schematics Connector End View Reference Master Electrical Component List Description and Operation Keyless Entry System 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 harness connector at the T10G Low Frequency Rear Bumper Antenna, ignition ON.
  2. Test for less than 1 V between the signal circuit terminal 1 and ground. ⇒ If 1 V or greater 2.1. Ignition OFF, disconnect the harness connector at the K9 Body Control Module, ignition ON. 2.2. Test for less than 1 V between the signal circuit and ground. ⇒ If 1 V or greater, repair the short to voltage on the circuit. ⇒ If less than 1 V, replace the K9 Body Control Module. ⇓ If less than 1 V
  1. Ignition OFF, install a DMM between the signal circuit terminal 1 and ground. Set the DMM to capture DC voltage using the MIN MAX function. Turn off autorange and manually set the DMM range to 000.0 V.
  2. Activate the antenna by pressing the trunk touch pad.
  3. Verify the MAX voltage captured by the DMM is greater than 1 V. ⇒ If 1 V or less 5.1. Ignition OFF, disconnect the harness connector at the K9 Body Control Module. 5.2. Test for infinite resistance between the signal circuit and ground. ⇒ If less than infinite resistance, repair the short to ground on the circuit. ⇓ If infinite resistance 5.3. Test for less than 2 Ω in the signal circuit end to end. ⇒ If 2 Ω or greater, repair the open/high resistance in the circuit. ⇒ If less than 2 Ω, replace the K9 Body Control Module. ⇓ If greater than 1 V
  4. Test for less than 1 V between the low reference circuit terminal 2 and ground. ⇒ If 1 V or greater 6.1. Ignition OFF, disconnect the harness connector at the K9 Body Control Module, ignition ON. 6.2. Test for less than 1 V between the low reference circuit and ground. ⇒ If 1 V or greater, repair the short to voltage on the circuit. ⇒ If less than 1 V, replace the K9 Body Control Module. ⇓ If less than 1 V
  1. Install a DMM between the signal circuit terminal 1 and the low reference circuit terminal 2. Set the DMM to capture DC voltage using the MIN MAX function. Turn off autorange and manually set the DMM range to 000.0 V.
  2. Activate the antenna by pressing the trunk touch pad.
  3. Verify the MAX voltage captured by the DMM is greater than 1 V. ⇒ If 1 V or less 9.1. Ignition OFF, disconnect the harness connector at the K9 Body Control Module. 9.2. Test for infinite resistance between the low reference circuit and ground. ⇒ If less than infinite resistance, repair the short to ground on the circuit. ⇓ If infinite resistance 9.3. Test for less than 2 Ω in the low reference circuit end to end. ⇒ If 2 Ω or greater, repair the open/high resistance in the circuit. ⇒ If less than 2 Ω, replace the K9 Body Control Module. ⇓ If greater than 1 V
  4. Replace the T10G Low Frequency Rear Bumper Antenna.
  5. Activate the antenna by pressing the trunk touch pad a minimum of three times to meet the conditions for setting the DTC
  6. Verify DTC B1451 is not set. ⇒ If DTC B1451 is set Replace the K9 Body Control Module. ⇓ If DTC B1451 is not set
  7. All OK. Repair Instructions Perform the Diagnostic Repair Verification after completing the repair. Low Frequency Rear Bumper Antenna Replacement Control Module References for keyless entry control module replacement, programming, and setup