GM Service Manual Online
For 1990-2009 cars only

ABS Warning Indicator

The electronic brake control module (EBCM) controls the ABS warning indicator. The EBCM turns the indicator ON for approximately 3 seconds during engine start-up in order to perform a bulb check. The EBCM flashes the ABS warning indicator in order to warn the driver of an ABS malfunction that may have degraded the base brake performance. A solid ABS warning indicator warns the driver of a problem affecting the operation of the ABS. The brake performance may remain normal when the ABS is disabled. Refer to ABS Operation in Antilock Brake System.

AIR Bag Warning Indicator

The inflatable restraint diagnostic energy reserve module with sensor (SDM) controls the air bag warning indicator. The SDM flashes the indicator 7 times when the ignition switch is turned to the RUN position. The SDM flashes the indicator 6 times when the ignition switch is turned straight to the START position. The SDM turns the indicator ON in order to warn the driver of a supplemental inflatable restraint (SIR) electrical system malfunction that may affect the operation of the SIR system. Refer to SIR System Operation in SIR.

Brake Warning Indicator

The brake warning indicator warns the driver of a base brake problem.

The brake warning indicator illuminates under the following conditions:

    • The ignition switch is in the bulb test position.
    • The ignition switch is in the START position.
    • The brake fluid is low in the master cylinder.
    • The parking brake switch is closed.
    • When certain ABS Diagnostic Trouble Codes (DTCs) are set under the control of the electronic brake control module (EBCM)

Refer to ABS Operation in Antilock Brake System.

Change Oil Soon Indicator

The powertrain control module (PCM) controls the change oil soon indicator. The PCM considers mileage and driving habits in order to determine when the change oil soon indicator should activate.

Press the accelerator pedal to the floor and release 3 times with the ignition in the RUN position and the engine off in order to reset the indicator after an oil change. The indicator reset is successful if the indicator flashes 3 times and then goes out. If the indicator remains on, repeat the resetting process.

Charge Warning Indicator

The generator digital regulator controls the charge warning indicator. The instrument cluster activates the indicator during engine startup in order to perform a bulb check. The digital regulator activates the indicator when an undervoltage (11.2 volts) or overvoltage (16.5 volts) condition exists.

Coolant Warning Indicator

The coolant warning indicator control monitors the engine coolant temperature signal from the engine coolant temperature sensor.

The indicator control illuminates the coolant warning under the following conditions:

    • The engine coolant temperature is approximately 255°F (124°C).
    • The sender resistance is approximately 53 ohms.
    • The ignition switch is in the RUN position with the engine off (during a bulb check).

Engine Coolant Temperature Gauge

Two coils, receiving battery voltage, operate the engine coolant temperature gauge. One of the coils is directly grounded and the other coil is grounded through the engine coolant temperature sender.

The engine coolant temperature has a resistance of 44 ohms at 260°F (125°C). The engine coolant temperature resistance increases at lower temperatures. The resistance is approximately 1365 ohms at 100°F (37°C). This causes the following results:

    • The current through the engine coolant temperature sender increases.
    • The temperature of one of the coils increases.
    • The coolant temperature decreases and moves the pointer.

Fasten Belts Indicator

The seat belt/ ignition key/ lamps alarm controls the fasten belts indicator. When the ignition switch is turned to the RUN position, with the engine off, the alarm sounds for 4 to 8 seconds or until the seat belt is fastened. Refer to Audible Warnings Circuit Description .

Fuel Gauge

The magnetic fields of the 2 coils move the fuel gauge pointer. The coils are at the right angles from each another. The battery applies voltage to one end of the E coil and the circuit divides at the opposite end of the E coil. One of the circuit paths continues to ground though the F coil. The other circuit paths continues to ground through the variable (40-250 ohms) resistor of the fuel level sender.

The resistance of the fuel level sender is low when the fuel tank is low. A large flow of current passes through the E coil and the fuel level sender resistor, pulling the pointer towards the E on the scale.

The fuel level sender resistance is high when the tank is full. A current flows through the F coil, moving the pointer towards the F on the scale.

The 2 coils, operating the pointer, protect the fuel gauge from changes in the voltage system. The signal is sent to the powertrain control module and, then to the instrument cluster.

High Beam Indicator

When the headlamps are operating and the headlamp dimmer switch is in the HIGH position, power is supplied to CKT 11. The power in CKT 11 powers up the high beam headlamps and the high beam indicator in the instrument cluster. Refer to Headlights Circuit Description in Lighting Systems.

Illumination Lamps

Voltage runs to the IP dimmer switch when the headlamp switch is in the PARK position or the HEAD position. Varying the IP dimmer switch allows for the adjustment of the voltage running to CKT 8 (from off to maximum brightness). Refer to Interior Lights Circuit Description in Lighting Systems.

Low Coolant Indicator

The low coolant indicator receives battery voltage when the ignition switch is in the following positions:

    • RUN
    • BULB TEST
    • START

The instrument cluster activates the indicator for approximately 1 second during engine start up in order to perform a bulb check. The engine coolant level indicator module grounds the indicator when the coolant level in the coolant reservoir is below the recommended level.

Low Oil Indicator

The powertrain control module (PCM) controls the low oil indicator. The PCM activates the indicator for 3 to 5 seconds when the ignition switch is turned to the RUN position, with the engine off, in order to perform a bulb check. The PCM samples the oil level once per ignition cycle, at the power-up point, if it meets the criteria indicating that the oil has sufficiently drained into the oil pan from the last power-down. If the engine coolant temperature is greater than 75°C (167°F) at the power-down, 3  minutes must elapse after the power-down in order for the PCM to sample the oil level. If the engine coolant temperature is less than 75°C (167°F) at the power-down, the PCM looks for at least an 11°C (20°F) drop in the engine coolant temperature in order for the PCM to sample the oil level at the power-up point.

Low Trac Indicator

The electronic brake control module (EBCM) controls the low trac indicator. The EBCM activates the indicator for approximately 3 seconds during the engine start up in order to perform a bulb check. The EBCM monitors the wheel speed sensors for any lock ups in the brakes (skid conditions). The EBCM engages the antilock brake system and activates the low trac indicator, if a skid condition is detected. Refer to ABS Operation in Antilock Brake System.

Oil Pressure Warning Indicator

The oil pressure warning indicator receives battery voltage when the ignition switch is in the following positions:

    • RUN
    • BULB TEST
    • START

The instrument cluster activates the indicator during the engine start up in order to perform a bulb check. The fuel pump/oil pressure switch grounds the indicator when the oil pressure is low.

Security Indicator

The theft deterrent module controls the security indicator. The theft deterrent module activates the indicator for approximately 5 seconds during the engine start up in order to perform a bulb check. The security indicator flashes if the theft deterrent module detects a fault in CKT 1073, CKT 1074, or if the ignition key is defective.

A solid security indicator illuminates if the theft deterrent module enters shut down mode in which the vehicle will not start. Refer to Vehicle Theft Deterrent (VTD) Operation in Theft Deterrent.

Service Engine Soon Indicator

The powertrain control module (PCM) controls the service engine soon indicator. Refer to Powertrain Control Module Description in Engine Controls - 3.1L (LG8).

Speedometer and Odometer

The vehicle speed sensor (VSS) is a gear driven permanent magnet generator. The vehicle transaxle houses the VSS. The VSS generates a sine wave output with a frequency proportional to the vehicle speed.

The powertrain control module (PCM) converts the CKT 389 signal to an output that switches to ground at a frequency of 4000 pulses per mile. The CKT 389 signal drives the speedometer and the odometer. Various other vehicle components use the CKT 389 signal. Refer to Powertrain Control Module Description in Engine Controls - 3.1L (LG8).

Tachometer (with gauges)

The tachometer displays the engine speed in RPM. The voltage pulses are taken from the ignition control module and sent to the tachometer. The tachometer responds to the pulses that increase the engine speed. The solid state circuits process the pulses into a signal that drives the pointer of the tachometer.

Turn Signal Indicators

The turn signal switch controls the turn signal lamps, sending voltage to the instrument cluster in order to activate the turn signal indicators. Both turn signal indicators flash when the emergency flashers are activated. Refer to Exterior Lights Circuit Description in Lighting Systems.