Keyless Entry System Inoperative

Keyless Entry System Inoperative

Diagnostic Instructions

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

Circuit/System Description

The keyless entry system is a vehicle entry device. The keyless entry will unlock the vehicle doors or open the trunk when a corresponding button on the keyless entry transmitter is pressed. This is accomplished by the key fob sending a radio frequency to the lift gate module (LGM). The signal is received by an internal antenna located within the LGM. The LGM interprets the signal and activates the requested function via a message over the serial data line. A low transmitter battery or radio frequency (RF) interference from aftermarket devices such as 2-way radios, power inverters, cellular phone chargers, computers, etc. may cause a system malfunction. High RF traffic areas, such as gas stations which use pay-at-the-pump RF transponders, may also cause interference that could lead to a malfunction.

Diagnostic Aids

For the J 43241 Keyless Entry Tester, inspect the keyless entry transmitter part number to determine that it is the correct model for the vehicle. An incorrect transmitter may pass the test, but it will not activate the keyless entry system.

Reference Information
Schematic Reference

Remote Function Schematics (Remote Function Schematics)
Connector End View Reference

Component Connector End Views (Component Connector End Views)
Description and Operation

Keyless Entry System Description and Operation
Electrical Information Reference

* Circuit Testing (Circuit Testing)
* Connector Repairs (Connector Repairs)
* Testing for Intermittent Conditions and Poor Connections (Testing for Intermittent Conditions and Poor Connections)
* Wiring Repairs (Wiring Repairs)

Scan Tool Reference

Control Module References (Control Module References)for scan tool information
Special Tools

J 43241 Keyless Entry Tester

Circuit/System Verification

1. Verify that the transmitter is the correct transmitter for the vehicle.

• If not the correct transmitter, replace the transmitter.

2. Verify the scan tool Fob Battery parameter for the appropriate keyless entry transmitter is OK.

• If no the specified value, replace the transmitter battery.

3. Verify the scan tool Fob Programmed parameter for the appropriate keyless entry transmitter is Yes.

• If no the specified value, program the transmitter. Refer to Transmitter Programming (Testing and Inspection).

4. Place the transmitter on the test pad of the J 43241 and press each button of the transmitter one at a time. The tester should sound a tone and illuminate a green light when each button is pressed.

• If one or more buttons does not sound the tone and illuminate the green light, replace the transmitter.

5. Operate the transmitter while observing the scan tool Last Fob Button Pressed parameter. The parameter should correspond with the function selected on the transmitter.

• If the parameter does not match the function selected on the transmitter, replace the transmitter.

6. If all circuits test normal, replace the LGM.

Repair Instructions

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

Control Module References (Control Module References)for LGM replacement, setup, and programming