Keyless Entry System Malfunction

Keyless Entry System Malfunction

Diagnostic Instructions

Circuit/System Description

The keyless entry system is a vehicle entry device. The keyless entry will unlock the vehicle doors or open the rear compartment when a corresponding button on the keyless entry transmitter is pressed. This is accomplished by the keyless entry transmitter sending a radio frequency to the remote functions receiver module, which then sends the signal to the Body Control Module (BCM). The BCM interprets the signal and activates the requested function. 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. A wrong model transmitter may pass the test, but it will not activate the vehicle remote system.

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

Scan Tool Reference

Control Module References for scan tool information

Special Tools

J 43241 Keyless Entry Tester

Circuit/System Verification

Attempt to program the keyless entry transmitter, refer to Replacing Keys . The transmitter should program.

Circuit/System Testing

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 Programmed parameter for the appropriate transmitter is Yes.

If not the specified value, program the transmitter. Refer to Replacing Keys .

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

If one or more buttons does not sound the tone and illuminate the green light, replace the transmitter battery and retest with the J 43241 . If the condition continues after battery replacement, replace the transmitter.

4. Operate the transmitter while observing the scan tool Fob Function parameter for the appropriate transmitter. 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.

5. Attempt to program the transmitter, refer to Replacing Keys . The transmitter should program.

If the transmitter does not program, test the keyless entry antenna for an open/high resistance. If the circuit tests normal, replace the K 84 remote functions receiver module.

Repair Instructions

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.