For 1990-2009 cars

## Keyless Entry System Malfunction with ATG

### 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 active keyless entry system is a vehicle entry device. The keyless entry will unlock the vehicle doors or open 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 functions receiver module, 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

• | This diagnostic applies to the active keyless entry system on vehicles equipped both with and without RPO ATS. The active keyless entry system operates when a button is pressed on the keyless entry transmitter.

• | 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. A wrong model transmitter may pass the test, but it will not activate the vehicle remote 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

• | Circuit Testing

• | Connector Repairs

• | Testing for Intermittent Conditions and Poor Connections

• | Wiring Repairs

#### Scan Tool Reference

Control Module References for scan tool information

#### Special Tools

J 43241 Keyless Entry Tester

### Circuit/System Verification

Attempt to program the keyless entry transmitter, refer to Transmitter Programming. The transmitter should program.

### Circuit/System Testing

1. Verify that the transmitter is the correct transmitter for the vehicle.

⇒ | If not the correct transmitter, replace the transmitter.

2. Verify the scan tool FOB Programmed parameter for the appropriate transmitter is Yes.

⇒ | If not the specified value, program the transmitter. Refer to Transmitter Programming.

3. Place the transmitter on the test pad of the J 43241 and press each transmitter button one at a time. The tester should sound a tone and illuminate a green light with each button press.

⇒ | If one or more buttons does not sound the tone and illuminate the green light, replace the transmitter battery and retest with the J 43241 . If the condition continues after battery replacement, replace the transmitter.

4. Operate the transmitter while observing the scan tool Fob Function parameter for the appropriate transmitter. 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.

5. Attempt to program the transmitter, refer to Transmitter Programming. The transmitter should program.

⇒ | If the transmitter does not program, test the keyless entry antenna for an open/high resistance. If the circuit tests normal, replace the K 84 remote functions receiver module..

### Repair Instructions

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

• | Transmitter Programming

• | Control Module References for module replacement, setup, and programming

## Keyless Entry System Malfunction with ATS

### 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.

### Diagnostic Fault Information

Circuit | Short to Ground | Open/High Resistance | Short to Voltage | Signal Performance
--- | --- | --- | --- | ---
Keyless Entry Antenna - Driver | B3119 00 | B3119 00 | B3119 00 | --
Keyless Entry Antenna - Passenger | B3120 00 | B3120 00 | B3120 00 | --
Keyless Entry Active Antenna -- Console | B3121 00 | B3121 00 | B3121 00 | --
Keyless Entry Antenna -- Trunk | B3122 00 | B3122 00 | B3122 00 | --
Keyless Entry Antenna -- Instrument Panel | B3123 00 | B3123 00 | B3123 00 | --
Keyless Entry -- Rear Fascia | B3124 00 | B3124 00 | B3124 00 | --

### Circuit/System Description

The passive keyless entry antennas are used as short range low frequency (LF) transmitters. As a vehicle with locked doors is approached with a key fob and the exterior door handle is pulled, the keyless entry antenna transmitter broadcasts a challenge to the key fob in an approximately 1 meter range. If the response from the key fob via radio frequency (RF) is valid, the locked door will be passively unlocked/unlatched and allow the door to be opened. The front doors will open with one pull of the front door handle. The rear doors will unlock with the first pull of the door handle and unlatch with the second pull of the door handle. 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.

### 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

• | Circuit Testing

• | Connector Repairs

• | Testing for Intermittent Conditions and Poor Connections

• | Wiring Repairs

#### Scan Tool Reference

Control Module References for scan tool information

#### Special Tools

J 43241 Keyless Enter Tester

### Circuit/System Verification

1. Ignition ON, observe the scan tool Exterior Driver Door Handle Switch, Exterior Passenger Door Handle Switch, and Trunk Release Switch parameters while operating their respective release handle/touch pad. The parameter should change between Active and Inactive as commanded.

⇒ | If the parameter does not cycle between the specified values, refer to Power Door Locks Malfunction.

2. With the vehicle locked, attempt to passively unlock and access the vehicle at the left door, right door, and rear compartment by approaching the vehicle with a valid transmitter and operating their respective release handle/touch pad. Each door and the rear compartment should unlock/unlatch and open.

⇒ | If both doors and the rear compartment do not unlock/unlatch and open, refer to Passive Transmitter Malfunction.

⇒ | If only one door or the rear compartment does not unlock/unlatch and open, refer to Antenna Circuit Malfunction.

### Circuit/System Testing

#### Passive Transmitter Malfunction

1. Place the keyless entry transmitter on the J 43241 and approach the vehicle. Operate the release handle/touch pad. Verify the J 43241 sounds a tone.

⇒ | If the tone does not sound, replace the transmitter battery and retest with the J 43241 . If the condition continues after battery replacement, replace the keyless entry transmitter.

2. If all circuits test normal, test or replace the keyless entry control module.

#### Antenna Circuit Malfunction

1. Ignition OFF, disconnect the harness connector at the inoperative keyless entry antenna.
2. Ignition ON, verify a test lamp does not illuminate between the signal circuit terminal A and ground.

⇒ | If the test lamp illuminates, test the signal circuit for a short to voltage. If the circuit tests normal, replace the keyless entry control module.

3. Install a DMM between the signal circuit terminal A and the low reference circuit terminal B. Set the DMM to capture AC voltage using the MIN MAX function.
4. Operate the release handle/touch pad Verify the DMM captured and AC voltage signal.

⇒ | If an AC voltage was not captured, test the signal circuit and the low reference circuit for a short to ground or an open/high resistance. If the circuits test normal, replace the keyless entry control module.

5. If all circuits test normal, test or replace the keyless entry antenna.

### Repair Instructions

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

• | Front Side Door Outside Handle Replacement

• | Control Module References for module replacement, setup, and programming