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Tahoe / Yukon Service Manual

DTC B1446

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 Interior Keyless Entry Antenna 3 High Signal 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
3554 Keyless Entry Antenna 3 Signal – High Reference B1446 11 B1446 13 B1446 12 —
3555 Keyless Entry Antenna 3 Signal – Low Reference B1446 11 B1446 13 B1446 12 —

Circuit/System Description The interior keyless entry antenna 3 is located inside of the rear compartment on the underside of the trunk lid and is used to establish low frequency communications with the keyless entry transmitter. As the ignition switch is pressed the BCM will transmit low frequency signals to this interior keyless entry antenna 3. 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 ignition switch is pressed or all the doors are closed. Battery voltage is between 9–16 V. Conditions for Setting the DTC B1446 11 The body control module detects a short to ground on the interior keyless entry antenna 3 signal circuit three or more times. B1446 12 The body control module detects a short to voltage on the interior keyless entry antenna 3 signal circuit three or more times. B1446 13 The body control module detects an open on the interior keyless entry antenna signal 3 circuit three or more times. Action Taken When the DTC Sets Doors will not unlock/lock when the exterior door handle button is pressed. Reduced or no coverage of the keyless entry transmitter inside the vehicle when the ignition switch is pressed or all doors are closed. 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 40 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 T10E Keyless Entry Antenna — Rear Compartment, 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 Stop/Start switch.
  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 Stop/Start switch.
  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 T 10E Keyless Entry Antenna — Rear Compartment.
  5. Activate the antenna by pressing the Stop/Start switch a minimum of three times to meet the conditions for setting the DTC.
  6. Verify DTC B1446 is not set. ⇒ If DTC B1446 is set Replace the K9 Body Control Module. ⇓ If DTC B1446 is not set
  7. All OK. Repair Instructions Perform the Diagnostic Repair Verification after completing the repair. Low Frequency Rear Compartment Antenna Replacement Control Module References for keyless entry control module replacement, programming, and setup