Keyless Entry System Malfunction (Active)
Keyless Entry System Malfunction (Active)
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 will unlock the vehicle doors or open/unlock 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 Control Door Lock Receiver, 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.
The Remote Control Door Lock Receiver uses the AM/FM antenna, located in the rear glass, to increase the range of the transmitter. A coax antenna cable connects the Remote Control Door Lock Receiver to the Radio Antenna Module. The Radio Antenna Module acts as an interface that combines the radio antenna and the keyless entry antenna. This allows both the Radio and the Remote Control Door Lock Receiver to use the AM/FM antenna.
Diagnostic Aids
* Unwanted or inadvertent door lock/unlock activation may be requested by the OnStar(R) Remote Link app. It is possible that a customer may be unaware of account usage, result in an unwanted or phantom door lock/unlock. If normal system diagnosis does results in an inability to verify the customer's concern, contact Technical Assistance Center (TAC).
* Because both the Remote Control Door Lock Receiver and the Radio use the Radio Antenna Module to interface with the AM/FM antenna located in the back glass, any damage to the antenna or a malfunction in the Radio Antenna Module will result in both a reduction in keyless entry system range and poor reception when listening to AM/FM radio.
* If available, the EL 43241 Keyless Entry Tester may be used to diagnose a low transmitter battery or a malfunctioning transmitter. To test, place the transmitter on the test pad of the EL 43241 and press each transmitter button one at a time, holding each button for three seconds. If the green light on the tester does not illuminate and a tone does not sound, first replace the transmitter battery and retest. If the malfunction continues after replacing the transmitter battery, replace the transmitter.
* When using the EL 43241 Keyless Entry Tester, first inspect the keyless entry transmitter part number to determine that it is the correct model for the vehicle. An incorrect part number transmitter may pass the test, but it will not activate the keyless entry system.
Reference Information
Schematic Reference
Remote Function Schematics [1][2]Electrical Diagrams
Connector End View Reference
Component Connector End Views Fuel Pump and Level Sensor Assembly
Description and Operation
Keyless Entry System Description and Operation 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
EL 43241 - Keyless Entry Tester
Circuit/System Verification
1. Verify that the keyless entry transmitter is correct for the vehicle. This can be accomplished by comparing the part number printed on the transmitter to the appropriate part number in the parts catalog.
• If the transmitter is incorrect
Replace the keyless entry transmitter.
• If the transmitter is correct
2. Ignition OFF, disconnect the keyless entry antenna coax cable from the K77 Remote Control Door Lock Receiver and from the K46 Radio Antenna Module.
3. Verify the antenna coax cable passes the coax cable component test. Refer to Component Testing.
• If the coax cable does not pass the test
Replace the antenna coax cable.
• If the coax cable passes the test
4. Connect the antenna coax cable to the K77 Remote Control Door Lock Receiver, ignition ON.
5. Test for greater than 4.5 V between the antenna coax cable center terminal and ground.
• If 4.5 V or less
Replace the K77 Remote Control Door Lock Receiver.
• If greater than 4.5 V
6. Connect the antenna coax cable to the K46 Radio Antenna Module.
7. Operate the transmitter while observing the scan tool Key Fob Function parameter for the appropriate transmitter.
8. Verify the scan tool Key Fob Function parameter corresponds with the function selected on the transmitter.
• If the Key Fob Function parameter does not correspond with the transmitter selection
Note: Before replacing the transmitter, inspect the transmitter battery contacts for any corrosion or damage. If no corrosion or damage is found, replace the transmitter battery and retest before replacing the transmitter.
1. Replace the keyless entry transmitter.
2. Operate the new transmitter while observing the scan tool Key Fob Function parameter for the transmitter.
3. Verify the scan tool Key Fob Function parameter correspond with the function selected on the transmitter.
• If the Key Fob Function parameter does not correspond with the transmitter selection, replace the K9 Body Control Module
• If the Key Fob Function parameter corresponds with the transmitter selection
4. All OK.
• If the Key Fob Function parameter corresponds with the transmitter selection
9. All OK.
Component Testing
1. Ignition OFF, disconnect the keyless entry antenna coax cable from the K77 Remote Control Door Lock Receiver and from the K46 Radio Antenna Module.
2. Test for less than 5 ohms between the coax cable center terminals end to end.
• If 5 ohms or greater
Replace the coax cable.
• If less than 5 ohms
3. Test for less than 5 ohms between the coax cable outer shield end to end.
• If 5 ohms or greater
Replace the coax cable.
• If less than 5 ohms
4. Test for infinite resistance between the coax cable center terminal and the outer shield.
• If less than infinite resistance
Replace the coax cable.
• If infinite resistance
5. All OK.
Repair Instructions
Perform the Diagnostic Repair Verification Verification Tests after completing the repair.
* Remote Control Door Lock and Theft Deterrent Transmitter Programming Testing and Inspection
* Control Module References Control Module References for Body Control Module replacement, programming, and setup