Keyless Entry System: Diagnosis Chevrolet TrailBlazer I

Diagnostic Starting Point - Keyless Entry

Begin the system diagnosis with DIAGNOSTIC SYSTEM CHECK - REMOTE KEYLESS ENTRY .

The Diagnostic System Check will provide the following information

1. The identification of the control module(s) which command the system
2. The ability of the control module(s) 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 Data Definitions

Fob 1 Battery: The scan tool displays OK to indicate a good battery voltage level was last received.

Fob 2 Battery: The scan tool displays OK to indicate a good battery voltage level was last received.

Fob 3 Battery: The scan tool displays OK to indicate a good battery voltage level was last received.

Fob 4 Battery: The scan tool displays OK to indicate a good battery voltage level was last received.

Last Fob Button Pressed: The scan tool displays Dr. Door Unlock, All Door Unlock, Door Lock, indicating the last input received from a programmed fob.

Fob 1 Programmed: The scan tool displays Yes/No. The scan tool displays Yes when the fob is programmed.

Fob 2 Programmed: The scan tool displays Yes/No. The scan tool displays Yes when the fob is programmed.

Fob 3 Programmed: The scan tool displays Yes/No. The scan tool displays Yes when the fob is programmed.

Fob 4 Programmed: The scan tool displays Yes/No. The scan tool displays Yes when the fob is programmed.

Symptoms - Keyless Entry

1. Perform «DIAGNOSTIC SYSTEM CHECK - REMOTE KEYLESS ENTRY»(ref-188876-S15742027492005090500000) before using the Symptom Tables in order to verify that all of the following are true: There are no DTCs set. The control module(s) can communicate via the serial data link.
2. Review the system operation in order to familiarize yourself with the system functions. Refer to Keyless Entry System Description and Operation.

Visual/Physical Inspection

1. Inspect for aftermarket devices which could affect the operation of the Keyless Entry System. Refer to CHECKING AFTERMARKET ACCESSORIES 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. «PANIC MODE INOPERATIVE»(ref-188876-S20481672392005090500000)
2. «KEYLESS ENTRY SYSTEM INOPERATIVE»(ref-188876-S33920975682005090500000)

Scheme 7

Scheme 8

Scheme 9

Scheme 10

Scheme 11

1. Insert a small coin between the two halves of the transmitter case at the slot provided near the key ring hole.
2. Twist the coin in order to open the case.
3. Open the transmitter case. NOTE: Refer to «HANDLING ESD SENSITIVE PARTS NOTICE»(ref-175132-S27809388882005041500000) in Cautions and Notices.
4. Remove the battery.

Scheme 12

1. Install the battery with the positive (+) side down. Use one 3 volt, type CR2032 battery, or the equivalent.
2. Ensure that the seal is in position.
3. Align the two halves of the case together and squeeze the case closed until the tabs are fully seated.

Method 2 - Scan Tool Required

1. Install a scan tool.
2. Turn the ignition ON, with the engine OFF.
3. Use the scan tool in order to access the Lift Gate Module (LGM) Special Function: Program Key Fobs menu.
4. Follow the directions on the scan tool in order to program the transmitters.
5. Operate the transmitter functions in order to verify correct system operation.

The keyless entry system is a supplementary vehicle entry device. Radio frequencies or discharged batteries may disable the system.

Keyless entry allows you to operate the following components

1. The door locks
2. The rear compartment lid release
3. The illuminated entry lamps
4. The panic alarm/instant alarm

The keyless entry system has the following main components

1. The transmitters
2. The Liftgate Module (LGM)

When you press a button on a transmitter, the transmitter sends a signal to the Liftgate Module. The module interprets the signal and activates the requested function via a class 2 message over the serial data line.