Circuit Description
The keyless entry antenna - rear compartment is located in the lower rear compartment area near the latch and is used as a short range low frequency (LF) transmitter. As a vehicle with a closed rear compartment lid is approached with a key fob and the exterior deck lid handle switch is pressed, the keyless entry antenna transmitter broadcasts a challenge to the key fob in an approximate 1 meter range. If the response from the key fob via radio frequency (RF) is valid, the latched rear compartment will be passively unlocked/unlatched, allowing the rear compartment area to be opened.
DTC Descriptor
This diagnostic procedure supports the following DTC:
DTC B3121 Keyless Entry Antenna 3 Performance
Conditions for Setting the DTC
The remote control door lock receiver (RCDLR) will set this DTC during antenna activation if the keyless entry antenna - rear compartment is open, shorted to battery or shorted to ground and an authentication occurs. The RCDLR can only set a DTC when it is the vehicle system voltage is between 9-16 volts.
Action Taken When the DTC Sets
The RCDLR will set and store a DTC B3121.
Conditions for Clearing the DTC
| • | The RCDLR no longer detects a open, short to power or short to ground on the antenna circuit. |
| • | The use of a scan tool. |
Test Description
The numbers below refer to the step numbers on the diagnostic table.
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Verifies that DTC B3121 is a current DTC.
-
Testing for power and ground to the keyless entry antenna.
Step | Action | Yes | No |
|---|---|---|---|
Schematic Reference: Keyless Entry Schematics Connector End View Reference: Keyless Entry Connector End Views | |||
1 | Did you perform the Diagnostic System Check - Vehicle? | Go to Step 2 | Go to Diagnostic System Check - Vehicle in Vehicle DTC Information |
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Important: To achieve service by pass mode, key ON engine OFF, a programmed key fob must be detected within the passenger compartment of the vehicle.
Does the scan tool display DTC B3121 as a current DTC? | Go to Step 3 | Go to Testing for Intermittent Conditions and Poor Connections in Wiring Systems | |
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Important: The voltage signal sent by the RCDLR to the passive antenna is a AC voltage signal. The DMM must be set on AC voltage setting to record the voltage pulse to the passive antenna. Important: Use a DMM to record the voltage pulse using the MIN MAX setting to capture the AC voltage pulse to the passive antenna. Important: The exterior rear compartment pad must be pressed to produce the voltage pulse to the passive antenna.
Was an AC voltage signal captured on the DMM? | Go to Step 6 | Go to Step 4 | |
4 | Test both the keyless entry antenna power and ground circuit for an open. Refer to Circuit Testing and Wiring Repairs in Wiring Systems. Did you find and correct the condition? | Go to Step 11 | Go to Step 5 |
5 | Inspect for poor connections at the RCDLR. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs in Wiring Systems. Did you find and correct the condition? | Go to Step 11 | Go to Step 7 |
6 | Inspect for poor connections at the keyless entry antenna - rear compartment. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs in Wiring Systems. Did you find and correct the condition? | Go to Step 11 | Go to Step 9 |
7 | Test the keyless entry antenna power circuit for a short to ground. Refer to Circuit Testing and Wiring Repairs in Wiring Systems. Did you find and correct the condition? | Go to Step 11 | Go to Step 8 |
8 | Replace the RCDLR. Refer to Control Module References in Computer/Integrating Systems for replacement, setup, and programming. Did you complete the replacement? | Go to Step 11 | -- |
9 | Test both the keyless entry antenna power and ground circuit for a short to power. Refer to Circuit Testing and Wiring Repairs in Wiring Systems. Did you find and correct the condition? | Go to Step 11 | Go to Step 10 |
10 | Replace the keyless entry antenna - rear compartment. Refer to Ignition Lock Key Transmitter Antenna Replacement - Rear Compartment . Did you complete the replacement? | Go to Step 11 | -- |
11 |
Does the DTC reset? | Go to Step 3 | System OK |
