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 B3122 04: Keyless Entry Antenna 4 Performance Open Circuit

DTC B3122 3B: Keyless Entry Antenna 4 Performance Internal Self Test Failed

Diagnostic Fault Information

Circuit

Short to Ground

Open/High Resistance

Short to Voltage

Signal Performance

Keyless Entry Antenna - Signal (4)

B3119 02

B3119 05

B3119 05

--

Keyless Entry Antenna - Low Reference (4)

--

B3119 05

--

--

Keyless Entry Antenna - Signal (5)

B3120 02

B3120 05

B3120 05

--

Keyless Entry Antenna - Low Reference (5)

--

B3120 05

--

--

Keyless Entry Antenna - Signal (3)

B3121 02

B3121 05

B3121 05

--

Keyless Entry Antenna - Low Reference (3)

--

B3121 05

--

--

Keyless Entry Antenna - Signal (2)

B3123 02

B3123 04

B3123 04

--

Keyless Entry Antenna - Low Reference (2)

--

B3123 04

--

--

Keyless Entry Antenna - Signal (1)

B3123 02

B3123 04

B3123 04

--

Keyless Entry Antenna - Low Reference (1)

--

B3123 04

--

--

Keyless Entry Active Antenna Supply Voltage

B3122 04

B3122 04

B3122 04

--

Keyless Entry Active Antenna Data Signal

B3122 04

B3122 04

B3122 04

--

Keyless Entry Active Antenna Clock Signal

B3122 04

B3122 04

B3122 04

--

Keyless Entry Active Antenna Low Reference

--

B3122 04

--

--

Circuit/System Description

The console active antenna is located in the center console and is used as a short range low frequency (LF) antenna. The keyless entry console active antenna is only used when a keyless entry transmitter battery is low or there is a interruption with the frequency transmission of the passive antennas located in the console and headliner. When a valid transmitter is placed into the fob pocket, the brake pedal is depressed, and the ignition button is pressed, the console active antenna broadcasts a challenge to the transmitter. This causes a low frequency coupling to occur between the transmitter and the console active antenna. If the response from the transmitter is a valid response, and all of the security requirements are met, the vehicle's engine will start, or be allowed to go into accessory mode.

Conditions for Running the DTC

A transmitter validation from the console active antenna is requested.

Conditions for Setting the DTC

An improper voltage level is seen at the console active antenna.

Action Taken When the DTC Sets

The console active antenna is ignored.

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 console active antenna.
  2. Ignition OFF, test for less than 20 ohms of resistance between the low reference circuit terminal 5 and ground.
  3. If greater than the specified range, test the low reference circuit for an open/high resistance. If the circuit tests normal, replace the RCDLR.
  4. Ignition ON, test for B+ between the supply voltage circuit terminal 2 and ground while commanding the scan tool Active Antenna output control ON.
  5. If not the specified value, test the supply voltage circuit for a short to ground or an open/high resistance. If the circuit tests normal, replace the RCDLR.
  6. Ignition OFF, disconnect the X2 harness connector at the RCDLR.
  7. Ignition ON, verify a test lamp does not illuminate between the following circuits and ground:
  8. • Signal circuit terminal B
    • Signal circuit terminal C
    If the test lamp illuminates, test the appropriate signal circuit for a short to voltage.
  9. Ignition OFF, test for infinite resistance between the following circuits and ground:
  10. • Signal circuit terminal B
    • Signal circuit terminal C
    If less than the specified value, test the appropriate signal circuit for a short to ground.
  11. Test for less than 2 ohms of resistance between the following signal circuits:
  12. • Terminal B at the RCDLR and terminal 3 at the console active antenna
    • Terminal C at the RCDLR and terminal 4 at the console active antenna
    If greater than the specified range, test the appropriate signal circuit for an open/high resistance.
  13. If all circuits test normal, test or replace the console active antenna.

Repair Instructions

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

    •  Ignition Lock Key Transmitter Antenna Replacement - Floor Console
    •  Control Module References for RCDLR replacement, setup, and programming