Service Information

Cruze

DTC B3123

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 B3123 02: Keyless Entry Aerial 5 Short to Ground

DTC B3123 05: Keyless Entry Aerial 5 High Voltage/Open

Diagnostic Fault Information

Circuit	Short to Ground	Open/High Resistance	Short to Voltage	Signal Performance
Keyless Entry Aerial - Rear Centre Console Signal	B3123 02	B3123 05	B3123 05	-
Keyless Entry Aerial - Rear Centre Console Low Reference	-	B3123 05	--	--

The rear centre console aerial is located in rear of the centre console assembly and is used to establish low frequency communications with the keyless entry transmitter. When the driver attempts to change the ignition status of the vehicle, i.e: starting the vehicle, the keyless entry control module communicates with the rear centre console aerial.

Conditions for Running the DTC

•	The touch pad in the driver door or passenger door handle is touched within 15 minutes of any door ajar status changing.

•	Any exterior door handle or handles is pulled.

•	The last door becomes closed.

•	Pressing the start/stop switch.

•	The scan tool activates a device control function to simulate the above actions.

Conditions for Setting the DTC

B3123 02

The keyless entry control module detects a short to ground on the rear centre console keyless entry aerial circuit.

B3123 05

The keyless entry control module detects a short to B+ or an open on the rear centre console keyless entry aerial circuit.

Action Taken When the DTC Sets

•	Vehicle will not detect the key fob in almost all locations inside the vehicle. If key fob is not detected then vehicle will not start when start/stop button is pressed.

•	Doors will not unlock when any door handle is pulled. Doors will not lock with touch pad. Rear closure will not open when doors are locked and touch pad is pressed.

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

Component Connector End Views

Description and Operation

Keyless Entry System Description and Operation : with ATH → without ATH

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

Note: Verify that the pins are correct for all of the aerials. Make sure to fix any problems with this rear centre console aerial first, then you can fix problems with other interior aerials DTCS B3122, B3124.

Ignition OFF, disconnect the harness connector at the T10K rear centre console aerial.
Ignition ON, verify a test lamp does not illuminate between the signal circuit terminal 1, connector on vehicle side, and vehicle ground and also does not illuminate between low reference signal circuit terminal 2, connector on vehicle side, and vehicle ground.

⇒	If the test lamp illuminates, disconnect the connector at the keyless entry control module, test the appropriate signal circuit for a short to voltage. If the circuit tests normal, replace the keyless entry control module.

Connect a DMM, set to capture DC voltage using the MIN MAX function, between the signal circuit terminal 1 and vehicle ground.

Note: Use DC voltage because comparing to vehicle ground.

Activate the rear centre console aerial by pressing the start/stop button or pulling any exterior door handle or handles. After hitting the min/max button looking for any voltage, verify the DMM captured a DC voltage signal.

⇒	If the DC voltage was not captured, test the signal circuit for a short to ground or an open/high resistance. If the circuit tests normal, replace the keyless entry control module.

Connect a DMM, set to capture DC voltage using the MIN MAX function, between the low reference circuit terminal 2 and vehicle ground.
Activate the rear centre console aerial by manually pressing the start/stop button or pulling any exterior door handle or handles. After hitting the min/max button looking for any voltage, verify the DMM captured a DC voltage signal.

⇒	If the DC voltage was not captured, test the low reference circuit for a short to ground or an open/high resistance. If the circuits test normal, replace the keyless entry control module.

⇒	Clear DTCs then activate the rear centre console aerial by pressing the start/stop button or pulling any exterior door handle or handles and check for DTCs again.

⇒	If DTC B3123 returns replace the T10K rear centre console aerial. Clear DTCs again then activate the rear centre console aerial by pressing the start/stop button or pulling any exterior door handle or handles and check for DTCs.

⇒	If DTC B3123 returns, replace the keyless entry control module.

Repair Instructions

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

Control Module References for keyless entry control module replacement, setup, and programming