1993 GMC Sonoma Owner's Manual - Page 127

Voltmeter Standard Cluster Digital Cluster KO278 Whenyourengineisnotrunning,but the ignitionison(in the Run position), the gageshowsyourbattery'sstate of charge in DC volts.When the engine is running, the gageshowsthecondition of the chargingsystem.Readings betweenthe low andhighwarningzonesindicate the normaloperatingrange. Onthedigitalcluster,a box around the voltmetersymbolwillbegin when the chargingsystemneedsservice. You canonlydriveforashorttimewiththereading youmustdrive,turn off allunnecessaryaccessories. to flash If in eitherwarningzone. Readingsineitherwarningzoneindicateapossibleproblemintheelectrical system.Havethevehicleservicedassoon as possible. mailer Wiring Harness Your vehiclemayhaveeithera5-wireor7-wireharness. The5-wireharnessisstoredalongtheleftrearframecrossmember.The harnesshasnoconnector,andyoushouldhave a qualifiedserviceperson wireyourharnessforyou. It must be routedout of yourvehicleandattached so thatthetrailerorthebodywon'tpull it. .7-75