Malfunction Indicator Lamp: Description and Operation

SERVICE VEHICLE SOON INDICATOR
Also known as "SERVICE TELLTALE" lamp or "SERVICE VEHICLE SOON" lamps, these lamps are used to inform the technician that a Non-Emissions releated malfunction of the Computerized Engine Control System or Body Control System has occurred, (a DTC has occurred). The "SERVICE TELLTALE" lamps are checked for proper operation while the engine is cranking, and will turn off after the engine is running.

Depending on the trouble code set, the "SERVICE TELLTALE" lamp or the "SERVICE VEHICLE SOON" lamp will come on and stay on while the malfunction is taking place. If a malfunction is intermittent, the service lamp that came on will go out when the malfunction is no longer detected by the computer.

SERVICE ENGINE SOON INDICATOR
Also known as "SERVICE TELLTALE" lamp or "SERVICE ENGINE SOON" lamp, this lamp is used to inform the technician that a malfunction of the Computerized Engine Control System or Body Control System has occurred, (a DTC has occurred). The "SERVICE TELLTALE" or "SERVICE ENGINE SOON" lamps are checked for proper operation while the engine is cranking, and will turn off after the engine is running.

Depending on the trouble code set, the "SERVICE TELLTALE" or "SERVICE ENGINE SOON" lamp will come on and stay on while the malfunction is taking place. If a malfunction is intermittent, the service lamp that came on will go out when the malfunction is no longer detected by the computer.