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

The keyless entry antennas are used as short range low frequency transmitters. As a vehicle with locked doors is approached with a keyless entry transmitter and the exterior door handle/rear closure touch pad is pressed, the keyless entry antenna broadcasts a challenge to the transmitter in an approximate one meter range. If the keyless entry control module verifies the response from the transmitter via radio frequency (RF) is valid, the keyless entry control module will send a message to the remote control door lock receiver and the locked door will be passively unlocked/unlatched and allow the door to be opened.

Unwanted or inadvertent door lock/unlock activation may be requested by the OnStar® 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).

A low transmitter battery may cause a system malfunction. More often a malfunction is the result of radio frequency (RF) interference from aftermarket devices which could include unexpected items such as nearby flat screen televisions, darkness sensing flood lights, or nearby cell phones. Other more common items that can cause a malfunction are 2-way radios, power inverters, cellular phone chargers, computers, 12 V power outlet USB adapters, etc. 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.

Conditions caused by external influences such are these are considered to be normal. Following this diagnostic will not diagnose an RF interference condition. If RF interference is suspected, question the customer about the conditions or location where the malfunction condition occurs.

The passive entry system will not function if the active entry system has a fault. Verify the active entry system operates before diagnosing the passive system.

Remote Function Schematics

Master Electrical Component List

Keyless Entry System Description and Operation

• Circuit Testing
• Connector Repairs
• Testing for Intermittent Conditions and Poor Connections
• Wiring Repairs

Control Module References for scan tool information

1. Ignition ON.
2. Verify that DTC B3119, B3120, or B3121 is not set.
• If any of the DTCs are set

  Refer to Diagnostic Trouble Code (DTC) List - Vehicle.

• If none of the DTCs are set
3. 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 keyless entry transmitter is incorrect

  Replace the keyless entry transmitter.

• If the keyless entry transmitter is correct
4. Verify the scan tool Exterior Driver Door Handle Switch, Exterior Passenger Door Handle Switch, and Trunk Lid Exterior Unlatch Switch parameters change between Active and Inactive while operating their respective exterior door handle/rear closure touch pad.
• If any of the parameters does not change

  Refer to Exterior Door Handle Switch Malfunction.

• If all of the parameters change
5. Lock the vehicle using the keyless entry transmitter.
6. Verify that each door and the rear compartment unlocks and opens by approaching the vehicle with a valid transmitter and operating their respective exterior door handle/rear closure touch pad.
• If both doors and the rear compartment do not unlock/unlatch and open

  Refer to Passive Transmitter Malfunction in Circuit/System Testing.

• If only one door or the rear compartment does not unlock/unlatch and open

  Refer to Antenna Circuit Malfunction in Circuit/System Testing.

• If both doors and the rear compartment unlocks/unlatches and opens
7. All OK.

1. Lock the vehicle using the keyless entry transmitter.
2. Verify that each door and rear compartment unlocks and opens by approaching the vehicle with a valid transmitter and operating their exterior door handle/rear closure touch pad.
• If both doors and the rear compartment do not unlock/unlatch and open
1. Replace the transmitter battery.
2. Lock the vehicle using the keyless entry transmitter.
3. Verify that each door and rear compartment unlocks and opens by approaching the vehicle with a valid transmitter and operating their respective release handle/touch pad.
• If both doors and the rear compartment do not unlock/unlatch and open, replace the keyless entry transmitter.
• If both doors and the rear compartment unlock/unlatch and open
4. All OK.
• If both doors and the rear compartment unlock/unlatch and open
3. The concern may be caused by temporary RF interference. Discuss the conditions in which the concern occurs with the customer. 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.

1. Ignition OFF, disconnect the harness connector at the appropriate T10 Keyless Entry Antenna, ignition ON.
2. Test for less than 1 V between the signal circuit terminal 1 and ground if the antenna being diagnosed uses terminals 1 and 2 according to the schematics or terminal 2 and ground if the antenna being diagnosed uses terminals 2 and 4 according to the schematics.
• If 1 V or greater
1. Ignition OFF, disconnect the harness connector at the K84 Keyless Entry Control Module, ignition ON.
2. Test for less than 1 V between the signal circuit and ground.
• If 1 V or greater, repair the short to voltage on the circuit.
• If less than 1 V, replace the K84 Keyless Entry Control Module.
• If less than 1 V

Note: When using the MIN MAX function, autorange on the DMM may not function properly. To ensure accurate test results, turn off autorange and manually set the DMM range to 000.0 V.

3. Ignition OFF, install a DMM between the signal circuit terminal 1 and ground if the antenna being diagnosed uses terminals 1 and 2 according to the schematics or terminal 2 and ground if the antenna being diagnosed uses terminals 2 and 4 according to the schematics Set the DMM to capture DC voltage using the MIN MAX function. Turn off autorange and manually set the DMM range to 000.0 V.
4. Lock the vehicle doors using the keyless entry transmitter. Activate the antenna by operating the appropriate exterior door handle/rear closure touch pad.
5. Verify the MAX voltage captured by the DMM is greater than 1 V.
• If 1 V or less
1. Ignition OFF, disconnect the harness connector at the K84 Keyless Entry Control Module.
2. Test for infinite resistance between the signal circuit and ground.
• If less than infinite resistance, repair the short to ground on the circuit.
• If infinite resistance
3. Test for less than 2 Ω in the signal circuit end to end.
• If 2 Ω or greater, repair the open/high resistance in the circuit.
• If less than 2 Ω, replace the K84 Keyless Entry Control Module.
• If greater than 1 V
6. Test for less than 1 V between the low reference circuit terminal 2 and ground if the antenna being diagnosed uses terminals 1 and 2 according to the schematics or terminal 4 and ground if the antenna being diagnosed uses terminals 2 and 4 according to the schematics
• If 1 V or greater
1. Ignition OFF, disconnect the harness connector at the K84 Keyless Entry Control Module, ignition ON.
2. Test for less than 1 V between the low reference circuit and ground.
• If 1 V or greater, repair the short to voltage on the circuit.
• If less than 1 V, replace the K84 Keyless Entry Control Module.
• If less than 1 V

Note: When using the MIN MAX function, autorange on the DMM may not function properly. To ensure accurate test results, turn off autorange and manually set the DMM range to 000.0 V.

7. Install a DMM between the signal circuit terminal 1 and the low reference circuit terminal 2 if the antenna being diagnosed uses terminals 1 and 2 according to the schematics or terminal 4 and ground if the antenna being diagnosed uses terminals 2 and 4 according to the schematics. Set the DMM to capture DC voltage using the MIN MAX function. Turn off autorange and manually set the DMM range to 000.0 V.
8. Lock the vehicle doors using the keyless entry transmitter. Activate the antenna by operating the appropriate exterior door handle/rear closure touch pad.
9. Verify the MAX voltage captured by the DMM is greater than 1 V.
• If 1 V or less
1. Ignition OFF, disconnect the harness connector at the K84 Keyless Entry Control Module.
2. Test for infinite resistance between the low reference circuit and ground.
• If less than infinite resistance, repair the short to ground on the circuit.
• If infinite resistance
3. Test for less than 2 Ω in the low reference circuit end to end.
• If 2 Ω or greater, repair the open/high resistance in the circuit.
• If less than 2 Ω, replace the K84 Keyless Entry Control Module.
• If greater than 1V
10. Replace the appropriate T10 Keyless Entry Antenna.
11. Lock the vehicle doors using the keyless entry transmitter. Activate the antenna by operating the appropriate exterior door handle/rear closure touch pad.
12. Verify that the door/rear compartment unlocks and opens when the exterior door handle/rear closure touch pad is operated.
• If the door/rear compartment does not unlock and open

  Replace the K84 Keyless Entry Control Module.

• If the door/rear compartment unlocks and opens
13. All OK.

Perform the Diagnostic Repair Verification after completing the repair.

• Remote Control Door Lock and Theft Deterrent Transmitter Programming
• Control Module References for module replacement, programming, and setup