For 1990-2009 cars

### 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
--- | --- | --- | --- | ---
Driver Door Lock/ Window Switch LOCK signal circuit | -- | 1 | 2 | --
Driver Door Lock/ Window Switch UNLOCK signal circuit | -- | 3 | 4 | --
1. Key fob door LOCK inoperative/Driver Door Lock switch functions normally/Passenger Door Lock switch LOCK function inoperative. 2. Key fob door lock functions inoperative/All door lock switch lock functions inoperative. 3. Key fob door UNLOCK function inoperative/Both Door Lock switches function normally.

4. Key fob door UNLOCK function inoperative/All door lock switch UNLOCK functions inoperative.

### 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 key fob sending a radio frequency to the body control module (BCM). The signal is received by an internal antenna located within the 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

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. An incorrect transmitter may pass the test, but it will not activate the keyless entry system.

### Reference Information

#### Schematic Reference

Door Lock/Indicator 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

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

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

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

⇒ | 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.

3. Verify the scan tool No. of Fobs Programmed parameter is greater than Fob 0.

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

4. Operate the transmitter while observing the scan tool Door Lock Output and Door Unlock Output parameters. The parameter should correspond with the function selected on the transmitter.

⇒ | If the parameter does not match the function selected on the transmitter, program the transmitter and retest. Refer to Transmitter Programming. If the condition continues after transmitter programming, replace the transmitter.

5. With a scan tool, command the door locks to LOCK and UNLOCK.

⇒ | If the door locks do not LOCK, test for a short to voltage or open/high resistance in the Driver Door Lock/ Window Switch LOCK signal circuit.

⇒ | If the door locks do not UNLOCK, test for a short to voltage or open/high resistance in the Driver Door Lock/ Window Switch UNLOCK signal circuit.

6. 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