GM Service Manual Online
For 1990-2009 cars only

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 B3120 00: Keyless Entry Antenna 2 Performance - RF Door Antenna

Diagnostic Fault Information

Circuit

Short to Ground

Open/High Resistance

Short to Voltage

Signal Performance

Keyless Entry Antenna Signal - LF Door

B3119 00

B3119 00

B3119 00

--

Keyless Entry Antenna Low Reference - LF Door

--

B3119 005

--

--

Keyless Entry Antenna Signal - RF Door

B3120 00

B3120 00

B3120 00

--

Keyless Entry Antenna Low Reference - RF Door

--

B3120 005

--

--

Keyless Entry Antenna Signal - Rear Compartment

B3121 00

B3121 00

B3121 005

--

Keyless Entry Antenna Low Reference - Rear Compartment

--

B3121 00

--

--

Keyless Entry Antenna Signal - Console Passive

B3123 00

B3123 00

B3123 00

--

Keyless Entry Antenna Low Reference - Console Passive

--

B3123 00

--

--

Keyless Entry Antenna Ignition - Console Active

B3122 00

B3122 00

B3122 00

--

Keyless Entry Antenna Data Signal - Console Active

B3122 00

B3122 00

B3122 00

--

Keyless Entry Antenna Clock Signal - Console Active

B3122 00

B3122 00

B3122 00

--

Keyless Entry Antenna Low Reference - Console Active

--

B3122 00

--

--

Circuit/System Description

The RF door handle antenna is located in the right front door handle assembly and is used to establish low frequency (LF) communications with the keyless entry transmitter. As a vehicle with locked doors is approached with a keyless entry transmitter, known as an electronic key, and the exterior door handle is activated, the keyless entry antenna broadcasts a challenge to the transmitter in an approximately 1 meter range. If the response from the transmitter via radio frequency (RF) is valid, the locked door will be passively unlocked/unlatched and allow the door to be opened.

Conditions for Running the DTC

The right front door handle is pulled

Conditions for Setting the DTC

An improper current level is seen on the keyless entry antenna - signal (5) circuit

Action Taken When the DTC Sets

No action is taken

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

Component Connector End Views

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 RF door handle antenna.
  2. Ignition ON, verify a test lamp does not illuminate between the signal circuit terminal A and ground.
  3. If the test lamp illuminates, test the signal circuit for a short to voltage. If the circuit tests normal, replace the RCDLR.
  4. 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.
  5. Pull the RF door handle. Verify the DMM captured an AC voltage signal.
  6. 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.
  7. If all circuits test normal, test or replace the RF door handle assembly.

Repair Instructions

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

    •  Front Side Door Outside Handle Replacement
    •  Control Module References for RCDLR replacement, setup, and programming