For 1990-2009 cars

### High Beam

The high beam indicator is turned ON by the cluster when requested by the body control module (BCM). This indicates to the operator of the vehicle that the high beams are ON. The indicator also comes ON when the flash-to-pass feature is used.

### Safety Belt Reminder

The safety belt reminder telltale is turned ON by the cluster when requested by the sensing and diagnostic module (SDM). If the driver's seat belt is not buckled, the safety belt reminder belt telltale will come ON and stay ON for 7 seconds. If the driver's seat belt is not buckled after 7 seconds, the telltale will remain ON for an additional 13 seconds, followed by about 1.5 minutes of flashing. If the driver's seat belt is buckled at any time after the initial 7 second period, the telltale will be immediately turned OFF.

### Air Bag Readiness

The sensing and diagnostic module (SDM) controls the Air Bag Readiness telltale by providing a signal to the cluster. The cluster uses the SDM signal to determine when to turn ON for the Air Bag Readiness telltale. The Air Bag Readiness telltale is used in the SIR system to notify the vehicle's operator of the following:

1. Correct SIR system operation by flashing seven times when the ignition switch is first turned ON. The telltale will turn OFF if the system is OK.
2. To warn the vehicle operator of SIR electrical system malfunctions which could potentially affect the operation of the SIR system.

The AIR BAG READINESS telltale is the key to driver notification of SIR system malfunctions. For proper operation, refer to SIR Diagnostic System Check in Restraints.

The AIR BAG READINESS telltale will be turned ON by the cluster for 2-3 seconds, when the ignition is turned to RUN for a visual system check.

### Service (Wrench) System Check

The SERVICE (Wrench) telltale is turned ON by the cluster when it receives a command from the powertrain control module (PCM) or the body control module (BCM). The PCM or BCM will turn the SERVICE (Wrench) telltale ON for all non-emission related diagnostic trouble codes (DTCs) that require that a telltale be turned ON, some DTCs do not turn ON a telltale but are stored to aid in diagnosis.

The SERVICE (Wrench) telltale will also be turned ON if the Antilock Brake System (ABS) control module has detected a fault in its own warning indicator system. If the ABS cannot turn ON its own telltale, a message will be sent to the BCM through the Key Word 2000 data bus to turn ON the SERVICE (Wrench) telltale.

The SERVICE (Wrench) telltale will be turned ON by the cluster for 2-3 seconds, when the ignition is turned to RUN, for a visual system check.

### Malfunction Indicator Lamp (MIL) (Service Engine Soon)

The MIL (SERVICE ENGINE SOON) telltale is turned ON by the cluster when it receives a command from the powertrain control module (PCM) (L61) engine or the body control module (BCM) (L81) engine. This indicates to the operator of the vehicle that there is a possible problem with the engine/transaxle control system.

The MIL (SERVICE ENGINE SOON) telltale will only be turned ON for emission related faults.

During engine start-up, the MIL (SERVICE ENGINE SOON) telltale is turned ON, for approximately 3 seconds, by the cluster for a visual system check.

### Low Fuel

The low fuel telltale is turned ON by the cluster when it receives a command from the body control module (BCM) (L81) engine or the powertrain control module (PCM) (L61) engine. The cluster will turn the LED ON when the fuel level in the tank reaches approximately 1.5 gallons.

The low fuel telltale will be turned ON by the cluster for 2-3 seconds, when the ignition is turned to RUN, for a visual system check.

### Engine Coolant Temperature Warning

The engine coolant temperature warning telltale is turned ON by the cluster when it receives a command from the powertrain control module (PCM) (L61) engine or the body control module (BCM) (L81) engine. When the coolant temperature is above the specified range, the engine coolant temperature warning telltale will be illuminated.

The engine coolant temperature warning telltale is turned ON by the cluster for 2-3 seconds, when the ignition is turned to RUN, for a visual system check.

### Low Coolant Warning

The low coolant warning telltale is turned ON by the cluster when it receives a command from the body control module (BCM). When the coolant level switch in the coolant reservoir is open, the BCM will command the telltale ON.

The low coolant warning telltale is turned ON by the cluster for 2-3 seconds, when the ignition is turned to RUN, for a visual system check.

### Engine Oil Pressure

The engine oil pressure telltale is turned ON by the cluster when it receives a command from the powertrain control module (PCM) (L61) engine or body control module (BCM) (L81) engine. This indicates to the operator of the vehicle that the engine oil pressure has dropped below a specified limit.

The engine oil pressure telltale will come ON, for approximately 2-3 seconds at engine start-up, until the oil pressure raises enough to open the oil pressure switch, for a visual system check.

### Change Oil Soon

The change oil soon telltale is turned ON by the cluster when it receives a command from the powertrain control module (PCM) (L61) engine or the body control module (BCM) (L81) engine. The engine control module (ECM) (L81) sends a message to the BCM over the CAN serial data link. The change oil soon telltale is commanded On based on a calculated value of time and mileage. This indicates to the operator of the vehicle that the oil should be changed as soon as possible.

The change oil soon telltale is turned ON by the cluster for 2-3 seconds, when the ignition is turned to RUN, for a visual system check.

### Low Traction

The low traction telltale is turned ON by the cluster when it receives a command from the BCM. The BCM receives this information from the EBTCM through the Key Word 2000 data link. When the traction control system attempts to prevent wheel slip, the low traction telltale will begin to flash.

The low traction telltale is turned ON by the cluster for 2-3 seconds, when the ignition is turned to RUN, for a visual system check. Refer to GM Oil Life System Resetting in Maintenance and Lubrication.

### ABS (Anti-lock Brake System)

The Antilock Brake System (ABS) telltale is turned ON by the cluster when it receives a command from the body control module (BCM). The BCM receives this information from the EBTCM through the Key Word 2000 data link.

The ABS telltale indicator lamp is turned ON, for approximately 3 seconds, during engine start-up for a visual system check.

If the telltale stays ON, it informs the driver that a problem has occurred and that the ABS system has been disabled. The vehicle should be taken in for service as soon as possible.

### Brake System Warning

The brake system warning telltale is turned ON by the cluster when it receives a command from the body control module (BCM). The BCM sends the command when any of the following inputs occur: low brake fluid switch (indicating low brake fluid), Antilock Brake System (ABS) control module (indicating a possible problem within the mechanical function of the brakes), or the park brake switch (indicating the park brake is engaged). This indicates to the operator of the vehicle that the park brake is engaged, brake fluid is low, or there is a possible problem in the basic brake system.

The brake system warning telltale is turned On by the cluster for 2-3 seconds, when the ignition is turned to RUN, for a visual system check.

### Charging System

The charging system telltale is turned ON by the cluster when it receives a command from the powertrain control module (PCM) (L61) engine or the body control module (BCM) (L81) engine. The engine control module (ECM) (L81) sends a message to the BCM over the CAN serial data link. This indicates to the operator of the vehicle that there is a possible problem in the charging circuit.

The charging system telltale will turn ON, for approximately 3 seconds, during engine start-up until the PCM or ECM senses voltage output by the generator for a system check.

### Reduced Power

The reduced power telltale is turned ON by the cluster when it receives a command from the body control module (BCM). The engine control module (ECM) (L81) engine sends a message to the BCM over the CAN serial data link.

The reduced power telltale is illuminated when the ECM is limiting engine torque in a low traction situation. This telltale is used only for the V6 (L81) engine application.

The reduced power telltale is turned ON by the cluster for 2-3 seconds, when the ignition is turned to RUN, for a visual system check.

### Decklid/Lift Gate Ajar

The decklid/lift gate ajar telltale is turned ON by the cluster when it receives a command from the body control module (BCM). When the lift gate has been opened, the cargo lamp switch will close providing input to the BCM. This indicates to the operator of the vehicle that the decklid (sedan) or lift gate (wagon) is ajar.

The decklid/lift gate ajar telltale will be turned ON by the cluster for 2-3 seconds, when the ignition is turned to RUN, for a visual system check.

### Washer Fluid Low

The washer fluid low telltale is turned ON by the cluster when it receives a command from the body control module (BCM). The low washer fluid switch is located in the washer fluid reservoir and is wired directly to the BCM.

When the fluid reaches a specified amount, the switch contacts will close and the BCM will request the telltale. This indicates to the operator of the vehicle that the washer fluid level is low.

The washer fluid low telltale will be turned ON by the cluster for 2-3 seconds, when the ignition is turned to RUN, for a visual system check.

### Daytime Running Lamps (DRL)

The DRL telltale is turned ON by the cluster when it receives a command from the body control module (BCM). The telltale will be ON whenever DRL is in operation.

The DRL telltale will turn OFF if the High or Low Beams headlamps are activated or if a High Beam Headlamp fails. However, if both high beams fail, the DRL will turn ON again. This is because the DRL circuitry is unable to identify this condition.

### Security

The security telltale is turned ON by the body control module (BCM). There is a wire directly from the security telltale (LED) to the BCM. The security telltale receives battery power from circuit 2540. The security telltale is grounded through circuit 264 by the BCM.

The security telltale is related to the Passlock system. For information on telltale operation, refer to the Passlock System.

### Shift Up

The shift up telltale is turned ON by the cluster when it receives a command from the powertrain control module (PCM) (L61) engine. The shift up telltale indicates to the operator of the vehicle when to shift to the next highest gear for maximum fuel mileage.

The shift up telltale will be turned ON by the cluster for 2-3 seconds, when the ignition is turned to RUN, for a visual system check.

### Left Turn Signal

The left turn signal lamp is switched to power by the left turn signal switch. When the switch is in the Left Turn position, current flows though the indicator lamp which is connected to ground within the cluster. This indicates to the operator of the vehicle that the left turn signal is operating. If both the left and right turn signal indicator lamps are flashing, the hazard flashers are ON.

### Right Turn Signal

The right turn signal lamp is switched to power by the right turn signal switch. When the switch is in the Right Turn position, current flows though the indicator lamp which is connected to ground within the cluster. This indicates to the operator of the vehicle that the right turn signal is operating. If both the right and left turn signal indicator lamps are flashing, the hazard flashers are ON.

### Instrument Cluster Illumination

The instrument cluster has 2 front flood illumination lamps and 4 rear back-lighting lamps. The signal to control these instrument cluster illumination lamps is a pulse width modulated voltage driven by the body control module (BCM).

The BCM varies the duty cycle based on the position of instrument panel dimmer knob. The duty cycle varies from approximately 20 percent LO to 100 percent HI. The BCM also sends class 2 messages to the cluster, to control odometer backlighting brightness, based on the position of the instrument panel dimmer knob.

#### Instrument Panel I/P Cluster Telltales

Telltale Gage or Lamp | Input To BCM | Input To Cluster
--- | --- | ---
Direct Wire | Serial Data | Direct Wire | Serial Data
ABS | EBTCM |  |  | BCM
Low Traction | EBTCM |  |  | BCM
Air Bag |  |  |  | SDM
Brake | X |  |  | BCM
Hot Coolant |  | ECM V6 PCM 4 CYL |  | BCM
DRL | X |  |  | BCM
Charging System |  | ECM |  | BCM
High Beam Lamp | X |  |  | BCM
Left Turn Lamp |  |  | X |
Low Brake Fluid | X |  |  | BCM
Low Coolant | X |  |  | BCM
Low Fuel |  | ECM V6 PCM 4 CYL |  | BCM V6 PCM 4 CYL
Washer Fluid Low | X |  |  | BCM
Service Engine Soon |  | ECM |  | BCM V6 PCM 4 CYL
Change Oil Soon |  | ECM V6 PCM 4 CYL |  | BCM
Oil Pressure |  | ECM |  | BCM V6 PCM 4 CYL
Reduced Power (V6 Only) |  | ECM |  | BCM
Right Turn Lamp |  |  | X |
Seat Belt |  |  |  | SDM
Security | X |  | BCM |
Service Wrench |  | ECM V6 PCM 4 CYL |  | BCM
Decklid/Lift Gate Ajar | X |  |  | BCM
Upshift |  |  |  | PCM
Speedometer |  | ECM V6 PCM 4 CYL |  | BCM
Odometer |  | ECM V6 PCM 4 CYL |  | BCM
Tachometer |  | ECM V6 PCM 4 CYL |  | BCM
Fuel Gage |  | ECM V6 PCM 4 CYL |  | BCM
Coolant Gage |  | ECM V6 PCM 4 CYL |  | BCM
Illumination Lamps | Direct wire from BCM