B3123

DTC B3123

Diagnostic Instructions

* Perform the Diagnostic System Check - Vehicle (Initial Inspection and Diagnostic Overview) prior to using this diagnostic procedure.
* Review Strategy Based Diagnosis (Initial Inspection and Diagnostic Overview) for an overview of the diagnostic approach.
* Diagnostic Procedure Instructions (Initial Inspection and Diagnostic Overview) provides an overview of each diagnostic category.



DTC Descriptors
DTC B3123 02
- Keyless Entry Antenna 5 & 6 Performance Short to Ground

DTC B3123 04
- Keyless Entry Antenna 5 & 6 Performance Open




Diagnostic Fault Information






Circuit/System Description

The headliner and console passive antennas are located in the rear headliner area and in the center console. They are used as short range low frequency (LF) antennas. The headliner and console antennas are used to determine transmitter placement within the vehicle. When a valid keyless entry transmitter is within the passenger compartment, the headliner and console antennas broadcast a challenge within the passenger compartment to the transmitter. If the response from the transmitter via radio frequency (RF) is a valid response, the antenna will determine there is a fob within the vehicle. If no response is received, the antenna determines that no fob is in the vehicle.


The headliner and console passive antennas share a driver within the remote control door lock receiver (RCDLR) and are wired in parallel. The RCDLR has no way to determine which antenna is receiving a valid response from a transmitter, only that a valid response is being received.


Conditions for Running the DTC

A transmitter validation is requested.


Conditions for Setting the DTC

An improper voltage level is seen on the keyless entry antenna - signal (1) or signal (2) circuit.


Action Taken When the DTC Sets

The headline and console passive keyless entry antennas are ignored. Vehicle starting will require the fob to be placed in the console pocket.


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 (Diagrams)
Connector End View Reference

Component Connector End Views (Connector Views)
Description and Operation

Keyless Entry System Description and Operation (Description and Operation)
Electrical Information Reference

* Circuit Testing (Component Tests and General Diagnostics)
* Connector Repairs (Component Tests and General Diagnostics)
* Testing for Intermittent Conditions and Poor Connections (Component Tests and General Diagnostics)
* Wiring Repairs (Component Tests and General Diagnostics)

Scan Tool Reference

Control Module References (Programming and Relearning) for Scan Tool Information


Circuit/System Testing

1. Ignition OFF, disconnect the harness connector at the console passive antenna.
2. Place the key fob near the headliner antenna and attempt to start the vehicle. The vehicle should start.

• If the vehicle does not start, refer to Headliner Antenna Circuit Malfunction.

3. Refer to Console Passive Antenna Circuit Malfunction.



Headliner Antenna Circuit Malfunction
1. Ignition OFF, disconnect the harness connector at the headliner antenna.
2. Install a DMM between the signal circuit terminal A and the low reference circuit terminal B. Set the DMM to capture AC voltage using the MIN MAX function.
3. Attempt to start the vehicle. Verify the DMM captured an AC voltage signal.

• If an AC voltage was not captured, test the signal circuit and the low reference circuit for a short to ground or an open/high resistance. If the circuits test normal, replace the RCDLR.

4. If all circuits test normal, test or replace the headliner antenna.



Console Passive Antenna Circuit Malfunction
1. Install a DMM between the signal circuit terminal A and the low reference circuit terminal B. Set the DMM to capture AC voltage using the MIN MAX function.
2. Attempt to start the vehicle. Verify the DMM captured an AC voltage signal.

• If an AC voltage was not captured, test the signal circuit and the low reference circuit for a short to ground or an open/high resistance. If the circuits test normal, replace the RCDLR.

3. If all circuits test normal, test or replace the console passive antenna.



Repair Instructions

Perform the Diagnostic Repair Verification (Verification Tests) after completing the diagnostic procedure.

* Ignition Lock Key Transmitter Antenna Replacement - Floor Console (Rear) (Ignition Lock Key Transmitter Antenna Replacement - Floor Console (Rear))Ignition Lock Key Transmitter Antenna Replacement - Floor Console (Cup Holder) (Ignition Lock Key Transmitter Antenna Replacement - Floor Console (Cup Holder))
* Ignition Lock Key Transmitter Antenna Replacement - Headliner (Ignition Lock Key Transmitter Antenna Replacement - Headliner)
* Control Module References (Programming and Relearning) for RCDLR replacement, setup, and programming