Keyless Entry System: Diagnosis Cadillac STS I

Diagnostic Starting Point - Keyless Entry

Begin the system diagnosis with the Diagnostic System Check - Vehicle in Vehicle DTC Information. The Diagnostic System Check will provide the following information

1. The identification of the control modules which command the system
2. The ability of the control modules to communicate through the serial data circuit
3. The identification of any stored diagnostic trouble codes (DTCs) and their status

The use of the Diagnostic System Check will identify the correct procedure for diagnosing the system and where the procedure is located.

Scan Tool Output Controls

Remote Control Door Lock Receiver (RCDLR) Output Controls

Scan Tool Data List

DDM Data List

IPM Data List

LRDM Data List

PDM Data List

RCDLR Data List

RIM Data List

RRDM Data List

Circuit Description

The keyless entry antenna - left is located in the left hand door pull handle and is used as a short range low frequency (LF) antenna. As a vehicle with locked doors is approached with a valid keyless entry transmitter and the exterior door handle is pulled, the keyless entry antenna broadcasts a challenge to the transmitter in an approximately 1 meter range. If the response from the transmitter via radio frequency (RF) is valid, the locked door will be passively unlocked/unlatched and allow the door to be opened.

DTC Descriptor

This diagnostic procedure supports the following DTC

DTC B3119 Keyless Entry Antenna 1 Performance

This vehicle has DTCs which include DTC Symptoms. For more information on DTC Symptoms, refer to DTC Symptom Description in Vehicle DTC Information.

DTC B3119

Conditions for Setting the DTC

The remote control door lock receiver (RCDLR) will set this DTC during antenna authentication if the keyless entry antenna - left is open, shorted to battery positive voltage, or shorted to ground. The RCDLR can only set a DTC when it is the vehicle system voltage is between 9-16 volts.

Action Taken When the DTC Sets

The RCDLR will set and store DTC B3119 Keyless Entry Antenna 1 Performance.

Conditions for Clearing the DTC

1. The RCDLR no longer detects an open, short to power, or short to ground on the antenna circuit.
2. The use of a scan tool

The keyless entry antenna - right is located in the right hand door pull handle and is used as a short range low frequency (LF) antenna. As a vehicle with locked doors is approached with a valid keyless entry transmitter, and the exterior door handle is pulled, the keyless entry antenna broadcasts a challenge to the transmitter in approximately a 1 meter range. If the response from the transmitter via radio frequency (RF) is valid, then the locked door will be passively unlocked/unlatched and allow the door to be opened.

This diagnostic procedure supports the following DTC

DTC B3120 Keyless Entry Antenna 2 Performance

This vehicle has DTCs which include DTC Symptoms. For more information on DTC Symptoms, refer to DTC Symptom Description in Vehicle DTC Information.

DTC B3120

The remote control door lock receiver (RCDLR) will set this DTC during antenna authentication if the keyless entry antenna - right is open, shorted to battery positive voltage, or shorted to ground. The RCDLR can only set a DTC when the vehicle system voltage is between 9-16 volts.

The RCDLR will set and store DTC B3120 Keyless Entry Antenna 2 Performance.

1. The RCDLR no longer detects an open, short to power, or short to ground on the antenna circuit.
2. The use of a scan tool.

The keyless entry antenna - rear compartment is located in the rear compartment area and is used as a short range low frequency (LF) antenna. As a vehicle with a closed rear compartment lid is approached with a keyless entry transmitter and the exterior rear compartment lid release pad is pressed, the keyless entry antenna broadcasts a challenge to the transmitter in an approximate 1 meter range. If the response from the transmitter via radio frequency (RF) is valid, the latched rear compartment will be passively unlatched, allowing the rear compartment lid to be opened.

This diagnostic procedure supports the following DTC

DTC B3121 Keyless Entry Antenna 3 Performance

This vehicle has DTCs which include DTC Symptoms. For more information on DTC Symptoms, refer to DTC Symptom Description in Vehicle DTC Information.

DTC B3121

The remote control door lock receiver (RCDLR) will set this DTC during antenna authentication if the keyless entry antenna - rear compartment is open, shorted to battery, or shorted to ground. The RCDLR can only set a DTC when it is the vehicle system voltage is between 9-16 volts.

The RCDLR will set and store a DTC B3121.

1. The RCDLR no longer detects a open, short to power, or short to ground on the antenna circuit.
2. The use of a scan tool

The console active antenna is located in the center console and is used as a short range low frequency (LF) antenna. The keyless entry console active antenna is only used when a keyless entry transmitter battery is low or there is a interruption with the frequency transmission of the passive antennas located in the console and headliner. When a valid transmitter is placed into the fob pocket, the brake pedal is depressed, and the ignition button is pressed, the console active antenna broadcasts a challenge to the transmitter. This causes a low frequency coupling to occur between the transmitter and the console active antenna. If the response from the transmitter is a valid response, and all of the security requirements are met, the vehicle's engine will start, or be allowed to go into accessory mode.

This diagnostic procedure supports the following DTC

DTC B3122 Keyless Entry Antenna 4 Performance

This vehicle has DTCs which include DTC Symptoms. For more information on DTC Symptoms, refer to DTC Symptom Description in Vehicle DTC Information.

DTC B3122

The remote control door lock receiver (RCDLR) will set this DTC during antenna activation if the circuits involved with the console active antenna's operation is open, shorted to battery, or shorted to ground. The RCDLR can only set a DTC when the vehicle system voltage is between 9-16 volts.

The RCDLR will set and store a DTC B3122.

1. The RCDLR no longer detects an open, a short to power, or a short to ground.
2. The use of a scan tool

The headliner and console antennas are located in the rear headliner area and in the center console. They are used as a short range low frequency (LF) antennas. The headliner and console antennas are used to determine transmitter placement within the vehicle. When a valid keyless entry transmitter is within the passenger compartment, the headliner and console antennas broadcast a challenge within the passenger compartment to the transmitter. If the response from the transmitter via radio frequency (RF) is a valid response, the antenna will determine there is a fob within the vehicle. If no response is received, the antenna determines that no fob is in the vehicle.

The headliner and console antennas share a driver within the remote control door lock receiver (RCDLR) and are wired in parallel. The RCDLR has no way to determine which antenna is receiving a valid response from a transmitter, only that a valid response is being received.

This diagnostic procedure supports the following DTC

DTC B3123 Keyless Entry Antenna 5&6 Performance

This vehicle has DTCs which include DTC Symptoms. For more information on DTC Symptoms, refer to DTC Symptom Description in Vehicle DTC Information.

DTC B3123

The RCDLR will set this DTC during antenna activation if the headliner and console antenna is open, shorted to battery, or shorted to ground. The RCDLR can only set a DTC when the vehicle system voltage is between 9-16 volts.

The RCDLR will set and store a DTC B3123.

1. The RCDLR no longer detects an open, a short to power, or a short to ground on the antenna circuit.
2. The use of a scan tool

Visual/Physical Inspection

1. Inspect for aftermarket devices which could affect the operation of the keyless entry system. Refer to «Checking Aftermarket Accessories»(ref-197533-S03944243902005101200000) in Wiring Systems.
2. Inspect the easily accessible or visible system components for obvious damage or conditions which could cause the symptom.

Symptom List

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

1. «Keyless Entry System Inoperative (Active)»(ref-197557-S16202093792005101200000) or «Keyless Entry System Inoperative (Passive)»(ref-197557-S09701690392005101200000)
2. «Key Fob Not Detected»(ref-197557-S33645300662005101200000)

Keyless Entry System Inoperative (Active)

Keyless Entry System Inoperative (Passive)

Circuit Description (RVS)

The remote control door lock receiver (RCDLR) receives a signal from the keyless entry transmitter indicating a remote vehicle start (RVS) request. A message is then sent to the instrument panel module (IPM) which determines if a crank request message will be sent to the engine control module (ECM) to activate RVS. To determine if conditions are correct for an RVS event, the IPM will request information from the rear integration module (RIM). The IPM looks at the following inputs

1. All vehicle doors are closed.
2. No keyless entry transmitters are inside the vehicle.
3. Rear compartment lid is not ajar.
4. Valid hood ajar switch closed signal.
5. The doors are locked.
6. The hazard switch is OFF.
7. Battery reconnect has not occurred.
8. Vehicle power mode is correct.

When the IPM determines all conditions meet those required for an RVS event, a message is sent via serial data to the IPM. The ECM relies on the RVS message from IPM, to enable RVS when the crank request signal is received. If the ECM does not receive a valid RVS message, it will not ground the control circuit of the crank relay and start the engine. While the ECM is in RVS mode it will cut fuel to the engine if any of the following additional conditions occur

1. Vehicle speed is greater than 0.
2. Transmission is not in P.
3. Excessive engine coolant temperature
4. Low oil pressure
5. The malfunction indicator lamp (MIL) is commanded ON.
6. Engine crank time is greater than 30 seconds.
7. Excessive engine speed.
8. Accelerator pedal position too high.
9. Remote start timer equals 0.
10. Vehicle Theft Deterrent (VTD) tamper.