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Service Indicator & Warning Lights - Except S & T Series GMC Cab & Chassis R2500

Procedures 3 illustrations ~530 words

Scheme 24

Scheme 24: SERVICE INDICATOR & WARNING LIGHTS

Scheme 25

Scheme 25

Scheme 26

Scheme 26

SERVICE ENGINE SOON WARNING LIGHT

Light will illuminate briefly when ignition is in ON position as a system check and will go out after the engine is started. Illumination during vehicle operation indicates that service to the computerized fuel, ignition or emission control system is required.

OIL PRESSURE GAUGE

Gauge indicates engine oil pressure in pounds per square inch. Oil pressure, not the amount of oil in the engine is indicated; however, oil level may affect oil pressure. Oil pressure varies with engine speed, oil viscosity or outside temperature. While engine is warming up, oil pressure will be higher than at normal operating temperature. If gauge registers in the low pressure zone, stop immediately and check the oil level.

CAUTIONDO NOT operate vehicle if oil pressure gauge continues to register in the low pressure zone.

OIL PRESSURE WARNING LIGHT

Under normal operating conditions, the light will come on as a test when ignition is in ON position and go out when the engine is started. If this light illuminates during normal vehicle operation, oil level should be checked immediately.

BRAKE SYSTEM WARNING LIGHT

Warning light indicates 2 things: either parking brake is ON or there is a problem with the dual hydraulic brake system. Light should come on briefly when ignition switch is turned to ON position, and parking brake is released. If light stays on or comes on during normal vehicle operation, immediate servicing is needed. BRAKE light may also indicate a problem in the rear wheel anti-lock brake system, if equipped.

CHARGING SYSTEM WARNING LIGHT

Light is shown as a battery symbol on the instrument cluster. It will illuminate briefly when ignition is turned to ON or START position, and should go out when the engine starts and alternator begins to charge. If light stays on or comes on when the engine is running, the battery is not being charged and the electrical system needs service.

VOLTMETER

Gauge shows battery's state of charge in DC volts when engine is not running but ignition is in ON position. When engine is running, gauge shows the condition of the charging system. Readings between low and high warning zones indicate normal operating range. Readings in either warning zone indicate a problem in the electrical system.

LOW COOLANT LIGHT

Light indicates a possible low engine coolant level. Check coolant level immediately.

COOLANT TEMPERATURE GAUGE

Gauge should register within NORMAL band under regular operating conditions. If gauge pointer rises into HOT range and stays there, stop vehicle, let engine cool and check coolant level.

COOLANT TEMPERATURE LIGHT

Light indicates engine coolant has overheated and the vehicle should be stopped as soon as possible. Let engine cool and check the coolant level.

CHECK GAGES LIGHT

Light indicates a problem in a monitored system. Check the gauges to determine where the problem exists and take corrective action.

GLOW PLUGS LIGHT (DIESEL ONLY)

With ignition in RUN position, GLOW PLUGS light will come on indicating engine is being warmed up for better starting. When light goes off, engine is ready to start.

SERVICE FUEL FILTER/WATER IN FUEL LIGHT (DIESEL ONLY)

Light indicates excessive water in fuel system. Service immediately to avoid possible damage to engine.