1999 Chevrolet Blazer Owner's Manual - Page 148

yellowblue If the light comes on continuously while driving and stays on, there may be a problem with the Passlock system. Your vehicle will not be protected by Passlock, and you should see your dealer. Also see "Content Theft-Deterrent" in the Index for additional information regarding the SECURITY light. NOTICE: Damage to your engine from neglected oil problems can be costly and is not covered by your warranty. Oil pressure may vary with engine speed, outside temperature and oil viscosity, but readings above the low pressure zone indicate the normal operating range. A reading in the low pressure zone may be caused by a dangerously low oil level or other problems causing low oil pressure. Service Four-Wheel-Drive Warning Light (If Equipped) This light should come on briefly when you turn on the ignition, as a check to show you it is working. Security Warning Light This light will come on briefly when you turn the key toward START. The light will stay on until the engine starts. If the light flashes, the PasslockR system has entered a tamper mode. If the vehicle fails to start, see "Passlock" in the Index. The SERVICE 4WD light comes on to indicate that there may be a problem with the drive system and service is required. Malfunctions can be indicated by the system before any problem is apparent, which may prevent serious damage to the vehicle. This system is also designed to assist your service technician in correctly diagnosing a malfunction. 2-84