For 1990-2009 cars

### Diagnostic Fault Information

• | 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 is a vehicle entry device. The keyless entry will unlock the vehicle doors when a corresponding button on the keyless entry transmitter is pressed. This is accomplished by the transmitter sending a radio frequency to the body control module (BCM). The signal is received by the BCM via an internal antenna. 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

When using the J 43241 Keyless Entry Tester, inspect the keyless entry transmitter part number to determine that it is the correct model for the vehicle. An incorrect P/N transmitter may pass the test, but it will not activate the particular keyless entry system.

### Reference Information

#### Schematic Reference

Remote Function Schematics

#### 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

Scan Tool Data List

#### Special Tools Required

J 43241 Keyless Entry Tester

### Circuit/System Testing

1. Verify that the transmitter being used is a correct P/N transmitter for the vehicle.

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

2. Using the J 43241 , place the keyless entry transmitter on the test pad and press each transmitter button one at a time. The green light on the tester should illuminate and a tone should sound with each button press.

⇒ | If no tone or illumination occurs with any of the buttons, replace the transmitter battery and retest the transmitter.

⇒ | If no tone or illumination occurs with one or more, but not all, buttons, replace the transmitter.

3. Ignition ON, verify the scan tool No. of Fob's Programmed parameter is Fob 1, Fob 2, Fob 3, or Fob 4.

⇒ | If not the specified value, reprogram the keyless entry transmitters. Refer to Transmitter Programming . If the keyless entry transmitters will not program, replace the BCM.

4. If all circuits test normal, replace the BCM.

### Repair Instructions

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

Control Module References for BCM replacement, setup, and programming