The Micro 420 Battery Tester should only be used to test vehicles equipped with gasoline engines. If the vehicle being tested has a diesel engine the OTC One Step Battery Analyzer and Charger special tool number OT-3641 or equivalent should be used to test the battery.Always use the Micro 420 Instruction Manual that was supplied with the tester as a reference. If the Instruction Manual is not available the following procedure can be used:Always wear appropriate eye protection and use extreme caution when working with batteries.If testing the battery OUT-OF-VEHICLE, clean the battery terminals with a wire brush before testing. If the battery is equipped with side post terminals, install and tighten the supplied lead terminal stud adapters. Do not use steel bolts. Failure to properly install the stud adapters, or using stud adapters that are dirty or worn-out may result in false test readings.If testing the battery IN-THE-VEHICLE, make certain all of the vehicle accessory loads are OFF, including the ignition.Connect the tester to the battery, the red clamp to the positive (+) terminal and the black clamp to the negative (–) terminal.Multiple batteries connected in parallel must have the ground cable disconnected to perform a battery test. Failure to disconnect may result in false battery test readings.Using the ARROW key select in or out of vehicle testing and press ENTER to make a selection.If not selected, choose the Cold Cranking Amp (CCA) battery rating. Or select the appropriate battery rating for your area (see menu). The tester will then run its self programmed test of the battery and display the results. Refer to the BATTERY TEST RESULTS TABLE.If REPLACE BATTERY is the result of the test, this may mean a poor connection between the vehicle's cables and battery exists. After disconnecting the vehicle's battery cables from the battery, retest the battery using the OUT-OF-VEHICLE test before replacing.While viewing the battery test result, press the CODE button and the tester will prompt you for the last 4 digits of the VIN. Use the UP/DOWN arrow buttons to scroll to the correct character; then press ENTER to select and move to the next digit. Then press the ENTER button to view the SERVICE CODE. Pressing the CODE button a second time will return you to the test results.BATTERY TEST RESULTSGOOD BATTERYReturn to serviceGOOD - RECHARGEFully charge battery and return to serviceCHARGE & RETESTFully charge battery and retest batteryREPLACE BATTERYReplace the battery and retest complete systemBAD-CELL REPLACEReplace the battery and retest complete systemThe SERVICE CODE is required on every warranty claim submitted for battery replacement.