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 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
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
- Verify that the transmitter is the correct transmitter for the vehicle.
⇒ | If not the correct transmitter, replace the transmitter. |
- Verify the scan tool Fob Battery parameter for the appropriate keyless entry transmitter is OK.
⇒ | If no the specified value, replace the transmitter battery. |
- Verify the scan tool Fob Programmed parameter for the appropriate keyless entry transmitter is Yes.
- 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. |
- 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. |
- If all circuits test normal, replace the LGM.
Repair Instructions
Perform the
Diagnostic Repair Verification after completing the diagnostic procedure.
Control Module References for LGM replacement, setup, and programming