Document ID: 3998920

Diagnostic Instructions

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.

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.

Diagnostic Aids

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).
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.
When the vehicle key is in the ignition, the keyless entry functions are disabled from all keyless entry transmitters.

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

EL 43241 - Keyless Entry Tester

Circuit/System Verification

Verify the Tire Pressure Monitoring System is functioning by adding air to one tire to see the air pressure display increase.

If the pressure does not increases
Refer toSymptoms - Tire Pressure Monitoring

If the pressure increases

Verify the VIN information for the vehicle transmitter is correct using theEL-52545 .

If the VIN is blank
Refer to Remote Control Door Lock and Theft Deterrent Transmitter Programming.

If the VIN is incorrect
This transmitter is not for this vehicle, it may already be programmed to work with a different vehicle but cannot be programmed to this vehicle.

If the VIN is correct

Verify the frequency of the transmitter matches the frequency of the tire pressure monitoring system and the remote control door lock receiver using the EL-52545 .

If the transmitter frequency is incorrect
Replace the vehicle transmitter.

If the transmitter frequency is correct

Verify the part number information for the vehicle transmitter is correct using the EL-52545.

If the vehicle transmitter part number is incorrect
Replace the vehicle transmitter.

If the vehicle transmitter part number is correct

Verify the transmitter output is above 20% on theEL-52545 signal strength meter by pressing a button on the transmitter ten times.

If the transmitter output is lower than 20%
Replace the transmitter battery.
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. For transmitter battery replacement refer to Remote Keyless Entry (RKE) System Operation in the owner manual.

If the transmitter output is higher than 20%

Using the scan tool read the number of transmitters learned in the K9 Body Control Module. Using theEL-52545 read the number of transmitters learned in the transmitter.

If the transmitters learned is less than the number programmed
Program the transmitter. Refer to Remote Control Door Lock and Theft Deterrent Transmitter Programming.

If the transmitters learned is equal to the number programmed

Lock the vehicle using the keyless entry transmitter.

If either the doors or the rear compartment do not unlock/unlatch and open
Refer to Circuit/System Testing.

If both doors and the rear compartment unlock/unlatch and open

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.

Circuit/System Testing

Ignition OFF and all vehicle systems OFF, scan tool disconnected, disconnect the harness connector at the K77 Remote Control Door Lock Receiver. It may take up to 2 min for all vehicle systems to power down.
Test for less than 30 Ω between the low reference circuit terminal 1 and ground.

If 30 Ω or greater

Ignition OFF, disconnect the harness connector at the K9 Body Control Module.
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 K9 Body Control Module.

If less than 30 Ω

Ignition ON.
Test for greater than 11.5 V between the B+ circuit terminal 4 and ground.

If 11.5 V or less

Ignition OFF, disconnect the harness connector at the K9 Body Control Module.
Test for infinite resistance between the B+ circuit and ground.

If less than infinite resistance, repair the short to ground on the circuit.

If Infinite resistance.

Test for less than 2 Ω in the B+ circuit end to end.

If 2 Ω or greater, repair the open/high resistance in the circuit.
If less than 2 Ω, replace the K9 Body Control Module.

If greater than 11.5 V

Test for 0.1–6 V between the serial data circuit terminal 2 and ground.

If less than 0.1 V

Ignition OFF, disconnect the harness connector at the K9 Body Control Module.
Test for infinite resistance between the serial data circuit and ground.

If less than infinite resistance, repair the short to ground on the circuit.

If infinite resistance

Test for less than 2 Ω in the serial data circuit end to end.

If 2 Ω or greater, repair the open/high resistance in the circuit.
If less than 2 Ω, replace the K9 Body Control Module.

If greater than 6 V

Ignition OFF, disconnect the harness connector at the K9 Body Control Module, ignition ON.
Test for less than 0.1 V between the serial data circuit and ground.

If 0.1 V or greater, repair the short to voltage on the circuit.
If less than 0.1 V, replace the K9 Body Control Module.

If between 0.1–6 V

Ignition OFF, disconnect the X1 and X2 harness connectors at the K9 Body Control Module, ignition ON.
Test for less than 0.1 V between the K9 Body Control Module serial data circuit terminal 26 X1 and ground.

If 0.1 V or greater
Repair the short to voltage on the circuit.

If less than 0.1 V

Ignition OFF.
Test for infinite resistance between the K9 Body Control Module serial data circuit terminal 26 X1 and ground.

If less than infinite resistance
Repair the short to ground on the circuit.

If infinite resistance

Test for less than 2 Ω between the K9 Body Control Module serial data circuit terminal 26 X1 and the K77 Remote Control Door Lock Receiver serial data circuit terminal 3.

If 2 Ω or greater
Repair the open/high resistance in the circuit.

If less than 2 Ω

Replace the K77 Remote Control Door Lock Receiver.
Verify the keyless entry functions operate.

If the keyless entry functions do not operate
Replace the K9 Body Control Module

If the keyless entry functions operate

All OK.

Repair Instructions

Perform the Diagnostic Repair Verification after completing the repair.

Transmitter Programming
Control Module References for body control module replacement, programming, and setup

Document ID: 2554457

Diagnostic Instructions

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

Circuit/System Description

Remote vehicle start begins as a radio frequency message received by the body control module (BCM) from a keyless entry transmitter. The BCM monitors system conditions such as content theft deterrent, hood ajar status, and body DTCs to determine if a remote vehicle start event will occur. If conditions are determined to be acceptable, the remote vehicle start message is sent to the engine control module (ECM). The ECM monitors system conditions such as engine control parameters and vehicle theft deterrent to determine if engine starting will be allowed. If conditions are acceptable, the ECM will initiate engine starting. During the engine run time in a remote vehicle start attempt, before the operator enters the vehicle, the ECM may discontinue engine operation if system conditions require it or a message is received from the BCM requesting the engine be turned OFF.

Diagnostic Aids

Unwanted or inadvertent door lock/unlock activation may be requested by the OnStar® Remote Link application. It is possible that a customer may be unaware of account usage, resulting in an unwanted or phantom door lock/unlock. If normal system diagnosis results in an inability to verify the customer’s concern, contact Technical Assistance Center (TAC).
If the vehicle has a current DTC that illuminates the malfunction indicator lamp (MIL), the cause of the DTC must be diagnosed before proceeding with the Remote Vehicle Start Inoperative diagnostic.
Only the first and second vehicle transmitters are able to control the remote vehicle start function.
The remote vehicle start system will not operate if any of the following conditions are present:

A current vehicle DTC that illuminates the malfunction indicator lamp (MIL)
The fuel level is low enough to cause the low fuel indicator to be active
The vehicle is in valet mode
On passive entry equipped vehicles, an additional key fob is left in the vehicle
More than 2 remote starts have been attempted
The hazard switch is in the ON position
A current hazard switch DTC is set
The vehicle hood is ajar
A current hood ajar DTC is set
A current door ajar system fault
A vehicle door is ajar
Incorrect BCM software is installed and vehicle start is not enabled
The content theft deterrent system detects an alarm trigger
Excessive engine RPM
Excessive coolant temperature
Accelerator pedal position greater than 0 percent
Vehicle not in park
Vehicle theft deterrent malfunction
A current automatic transmission shift lock control system DTC is set
A vehicle speed sensor signal is detected by the ECM

Reference Information

Schematic Reference

Remote Function Schematics

Connector End View Reference

Master Electrical Component List

Description and Operation

Keyless Entry System Description and Operation

Electrical Information Reference

Scan Tool Reference

Control Module References for scan tool information

Circuit/System Verification

Verify that the keyless entry functions operate with all available keyless entry transmitters.

If any keyless entry functions do not operate properly
Refer to Keyless Entry System Malfunction.

If all keyless entry functions operate properly

Verify that no Diagnostic Status History or Start Disable items are present in the scan tool BCM Remote Start Diagnostic Status History and the ECM Remote Vehicle Start Disable History parameters.

If remote vehicle start disable history items are present
Refer to the appropriate subsection in which the malfunction occurred.

If remote vehicle start disable history items are not present

Verify all scan tool BCM Content Theft Trigger History parameters display None.

If any BCM Content Theft Trigger History parameter does not display None
Refer to Content Theft Deterrent Malfunction.

If all BCM Content Theft Trigger History parameters display None

All OK.

Document ID: 2176608

Note: The following steps must be completed before using the symptom tables.

Perform Diagnostic System Check - Vehicle before using the Symptom Tables in order to verify that all of the following are true:

There are no DTCs set.
The control modules can communicate via the serial data link.

Review the system operation in order to familiarize yourself with the system functions. Refer to Keyless Entry System Description and Operation.

Visual/Physical Inspection

Inspect for aftermarket devices which could affect the operation of the Keyless Entry System. Refer to Checking Aftermarket Accessories.
Inspect the easily accessible or visible system components for obvious damage or conditions which could cause the symptom.

Intermittent

Faulty electrical connections, wiring, terminals, connectors, poor voltage and ground connections, temperature sensitivity, electromagnetic interference, electrical noise and/or incorrect control module installed may be the cause of intermittent conditions. Refer to Testing for Intermittent Conditions and Poor Connections.

Symptom List

Refer to a symptom diagnostic procedure from the following list in order to diagnose the symptom:

Operation	Task	Skill	Hours
Remove & Replace	Keyless Entry Components · Receiver, R&R	B	0.4
Remove & Replace	Keyless Entry Components · Transmitter, R&R	B	0.5

Keyless Entry

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