AUTOOL DM303 Digital Multimeter Car Circuit Tester

AUTOOL DM303Product OverviewAUTOOL DM303 is a handheld automotive diagnostic multimeter that integrates a digital multimeter, oscilloscope, automotive circuit tester, cranking test, injector test, relay test, analog signal output, ignition pulse test, and K/CAN line data reading for vehicle electrical diagnosis.Digital Multimeter 500kHz Oscilloscope K/CAN Line Data Injector / Relay Test2.8-inchColor DisplayDC 0-1000VVoltage Range1Hz-1MHzFrequency Range3 YearsWarranty Click to enlargeBefore You Order And UseBefore You Order And UseDM303 and DM301 are shipped without batteries. Confirm the battery type before use, and do not charge dry batteries inside the device.Batteries Are Not IncludedDM303 / DM301 is shipped without batteries due to shipping and battery restrictions. Batteries need to be purchased separately.Dry Battery OptionYou can install 4pcs 1.5V dry batteries for normal use. Do not charge dry batteries through the device.Lithium Battery OptionYou may install a compatible lithium battery by yourself. The reference image shows a 503450 3.7V 1000mAh lithium battery style.Charge Only Lithium SetupIf a compatible rechargeable lithium battery is installed, it can be charged. Dry batteries must not be charged.Battery Safety ReminderDo not mix dry batteries and rechargeable lithium battery setups.Confirm the battery direction, voltage, and connector style before installation.Contact AUTOOL Store if you are not sure whether your lithium battery is compatible. Click to enlargeProduct ComparisonProduct ComparisonDM303 is the more advanced choice if you need more automotive diagnostic modes, more wiring options, injector and relay tests, cranking test, analog signal output, automotive circuit testing, and K/CAN related line data checks.Function LevelDM301 focuses on basic measurement and oscilloscope-style checks. DM303 adds advanced automotive diagnostic modes such as injector, relay, circuit, cranking, analog signal, CAN line, and K/LIN-related data reading.Measurement ModesThe comparison chart lists DM301 with 6 basic functions and DM303 with 12 function types. DM303 is better for complex vehicle electronic control system diagnosis.Power SupplyDM301 supports dry battery, Type-C, and optional lithium battery configuration. DM303 further supports dry battery, Type-C, 12V rechargeable battery configuration, and optional lithium battery setup depending on installation.AccessoriesDM303 provides more test lead types than DM301. It is more flexible for automotive circuit, injector, relay, signal, K/CAN, and multimeter testing scenarios.Shared DesignBoth models have a 2.8-inch color screen, flashlight function, toolbox configuration, and support for trucks, sedans, buses, electric vehicles, and other vehicle types. Click to enlargeKey FeaturesKey FeaturesDM303 combines standard electrical measurement with vehicle-focused circuit and signal tests, helping technicians check voltage, current, resistance, frequency, waveforms, starting voltage, injectors, relays, ignition signals, analog output, and K/CAN line data.True RMS Auto-Ranging MultimeterMeasures DC / AC voltage, current, resistance, diode, and frequency. Auto range helps reduce manual range selection, while True RMS improves reading reliability for electrical testing.500kHz OscilloscopeThe handheld oscilloscope supports 500kHz bandwidth and one-button automatic waveform display for observing slowly changing or automotive circuit signals.Automotive Circuit TestSupports automotive circuit voltage and drive-current checks. It can help check battery voltage, vehicle circuits, ECU-related wiring, and other electrical parts through the proper test leads.Cranking TestDuring vehicle starting, a minimum battery voltage above 9.6V is generally considered normal. If the value drops below 9.6V, the battery may be aging or weak.Injector And Relay TestDM303 can drive and detect injector signals, and can also support relay testing. It supports electromagnetic injectors including GDI injectors, but does not support 120V injectors.Analog Signal And K/CAN Line DataSupports 5V square wave, 5Vpp sine wave, and 12V square wave output with the proper cable and battery setup. K/CAN line data reading helps circuit-level diagnosis, but it is not a full vehicle scan tool. Click to enlarge Click to enlarge Click to enlarge Click to enlarge Click to enlargeSpecificationsAUTOOL DM303 Product SpecificationsDM303 supports wide voltage, current, resistance, and frequency ranges, plus automotive circuit drive current and injector drive signal output for vehicle electrical diagnosis.Core SpecificationsProductAUTOOL DM303 Auto Diagnostic MultimeterDisplay2.8-inch color screenVoltage Measurement RangeDC 0-1000V, AC 0-700VCurrent Measurement Range0-20A, 0-200mAResistance Measurement Range0-1MΩFrequency Measurement Range1Hz-1MHzAutomotive Circuit Drive Current0-5AInjector Drive Signal Output500-6000rpmOscilloscope Bandwidth500kHzWorking Temperature0°C-40°C / 32°F-104°FPower Supply MethodDry battery, Type-C, 12V rechargeable battery configuration, and optional lithium battery setup depending on installationData Lock / ClearSupportedLanguage SupportMulti-language interface including English, French, Portuguese, Polish, Spanish, Japanese, Russian, Italian, German, Dutch, Korean, Chinese, and other supported firmware optionsApplicable Vehicle ModelsTrucks, sedans, buses, electric vehicles, and other vehicle typesWarranty3-year support for eligible non-human damage casesProduct StructureStructure OverviewDM303 is designed for workshop and outdoor electrical diagnosis with a color screen, shortcut keys, multiple input ports, DB15 interface, built-in light, data interface, back bracket, and protective toolbox.Screen And KeysDisplay screen, power key, hold key, direction keys, return key, enter key, function keys, measurement mode switching, and lighting key.Measurement Ports10A current input, mA / μA measurement input, COM measurement input, and diode / voltage / resistance / frequency measurement input.Diagnostic InterfacesDB15 interface, SD card slot / data interface, and back bracket for convenient display positioning during testing.ToolboxThe plastic toolbox stores the main unit and accessories, helps protect the instrument, and makes it easier to carry to repair sites. Click to enlarge Click to enlarge Core SpecificationsProductAUTOOL DM303 Auto Diagnostic MultimeterDisplay2.8-inch color screenVoltage Measurement RangeDC 0-1000V, AC 0-700VCurrent Measurement Range0-20A, 0-200mAResistance Measurement Range0-1MΩFrequency Measurement Range1Hz-1MHzAutomotive Circuit Drive Current0-5AInjector Drive Signal Output500-6000rpmOscilloscope Bandwidth500kHzWorking Temperature0°C-40°C / 32°F-104°FPower Supply MethodDry battery, Type-C, 12V rechargeable battery configuration, and optional lithium battery setup depending on installationData Lock / ClearSupportedLanguage SupportMulti-language interface including English, French, Portuguese, Polish, Spanish, Japanese, Russian, Italian, German, Dutch, Korean, Chinese, and other supported firmware optionsApplicable Vehicle ModelsTrucks, sedans, buses, electric vehicles, and other vehicle typesWarranty3-year support for eligible non-human damage cases Product StructureStructure OverviewDM303 is designed for workshop and outdoor electrical diagnosis with a color screen, shortcut keys, multiple input ports, DB15 interface, built-in light, data interface, back bracket, and protective toolbox.Screen And KeysDisplay screen, power key, hold key, direction keys, return key, enter key, function keys, measurement mode switching, and lighting key.Measurement Ports10A current input, mA / μA measurement input, COM measurement input, and diode / voltage / resistance / frequency measurement input.Diagnostic InterfacesDB15 interface, SD card slot / data interface, and back bracket for convenient display positioning during testing.ToolboxThe plastic toolbox stores the main unit and accessories, helps protect the instrument, and makes it easier to carry to repair sites. Click to enlargeWhat Is In The BoxWhat Is In The BoxThe packing list image shows the DM303 main unit, manual, retail box, portable toolbox, and multiple test leads. Batteries are not included and need to be purchased separately.Main UnitAUTOOL DM303 auto diagnostic multimeterStoragePortable protective toolbox and retail boxDocumentationUser manual shown in the package imageTest LeadsMultifunction test lead, battery clip cable, multimeter probes, jumper / adapter cables, and additional test leads shown in the package imageBattery NoticeBatteries are not included. Use 4pcs 1.5V dry batteries or a compatible lithium battery setup according to the battery rules.Related ProductsRelated ProductsCompare DM303 with related AUTOOL multimeter options before choosing a professional automotive diagnostic multimeter or a smaller general-purpose digital multimeter.Select options This product has multiple variants. The options may be chosen on the product page Add to wishlist Add to compare Quick view iconQuick view Automotive Diagnostic MultimeterAUTOOL DM301 Auto Digital Multimeter Car Circuit TesterRated 0 out of 5(0) From US$109.00 Select options This product has multiple variants. The options may be chosen on the product page Select options This product has multiple variants. The options may be chosen on the product page Add to wishlist Add to compare Quick view iconQuick view Automotive Diagnostic MultimeterAUTOOL DM202 Mini Digital Multimeter NCV Tester Ture-RMS 4000 CountsRated 0 out of 5(0) From US$39.00 Select options This product has multiple variants. The options may be chosen on the product page Select options This product has multiple variants. The options may be chosen on the product page Add to wishlist Add to compare Quick view iconQuick view Automotive Diagnostic MultimeterAUTOOL DM103 Digital LCR Tweezer for Resistance Capacitance and InductanceRated 5.00 out of 5(1) From US$40.00 Select options This product has multiple variants. The options may be chosen on the product page Select options This product has multiple variants. The options may be chosen on the product page Add to wishlist Add to compare Quick view iconQuick view Automotive Circuit TesterAUTOOL BT250 Car Electrical Circuit Tester 6V-30VRated 0 out of 5(0) From US$39.00 Select options This product has multiple variants. The options may be chosen on the product page Manual And DownloadsManual And DownloadsDownload the DM303 manual for battery setup, test modes, wiring, interface operation, and safe-use guidance. Click to enlargeAUTOOL DM303 Manual PDFOpen the PDF manual before using advanced wiring, signal, injector, relay, K/CAN, and oscilloscope functions. Download ManualNeed Function Or Battery Confirmation?Contact AUTOOL Store before ordering if you need to confirm DM303 battery type, lithium battery charging, accessories, DM301 / DM303 differences, injector test limits, or K/CAN line data use.Email[email protected] WhatsApp 86 189 2647 7404Questions And AnswersThese answers cover battery setup, charging limits, DM301 / DM303 differences, injector testing, cranking test results, measurement ranges, K/CAN line data, accessories, languages, and warranty support. Does AUTOOL DM303 Include Batteries? No. DM303 / DM301 is shipped without batteries. You need to buy batteries separately. You can use 4pcs 1.5V dry batteries, or install a compatible lithium battery setup by yourself. Can I Charge Dry Batteries Inside DM303? No. Do not charge dry batteries. Only a compatible rechargeable lithium battery setup can be charged. If you are not sure whether your battery is rechargeable or compatible, contact AUTOOL Store before charging. What Lithium Battery Style Is Shown For DM303? The reference image shows a 503450 3.7V 1000mAh lithium battery style. Confirm the connector, size, and compatibility before installing a lithium battery. What Is The Difference Between DM301 And DM303? DM301 focuses on basic measurement functions such as voltage, current, resistance, frequency, oscilloscope, and ignition pulse signal testing. DM303 adds more automotive diagnostic functions, including fuel injector testing, relay testing, automotive circuit testing, cranking test, signal simulation, CAN line data reading, and K/LIN-related line data reading. Does DM303 Support Injector Testing? Yes. DM303 can drive the injector for testing and can also detect real-time injector signals. It supports electromagnetic injectors including GDI injectors, but it does not support 120V injectors. What Does The Cranking Test Result Mean? During vehicle startup, DM303 checks the minimum battery voltage. A minimum voltage above 9.6V is generally considered normal. If it drops below 9.6V, the battery may be aging, weak, or in need of further inspection. What Measurement Ranges Does DM303 Support? DM303 supports DC 0-1000V and AC 0-700V voltage measurement, 0-20A and 0-200mA current measurement, 0-1MΩ resistance measurement, and 1Hz-1MHz frequency measurement. Frequency testing needs a valid signal source with voltage greater than 1V. Can DM303 Replace A Full Vehicle Diagnostic Scanner? No. DM303 is an automotive diagnostic multimeter and circuit / signal testing tool. K/CAN line data reading helps with circuit-level diagnosis, but it should not be described as a complete vehicle diagnostic scanner. What Accessories Are Included? Refer to the Packing List image for final package contents. The package shows the DM303 main unit, user manual, retail box, portable toolbox, multifunction test lead, battery clip cable, multimeter probes, jumper / adapter cables, and additional test leads. Batteries are not included. Which Languages Does DM303 Support? DM303 supports a multi-language interface, including English, French, Portuguese, Polish, Spanish, Japanese, Russian, Italian, German, Dutch, Korean, Chinese, and other supported firmware options. If a specific language is required, confirm before ordering. How Long Is The Warranty? AUTOOL provides 3-year warranty support for eligible non-human damage cases. For qualifying cases, AUTOOL may reissue parts free of charge within the warranty period.Related GuidesRelated GuidesUse these related guides to learn more about AUTOOL electrical test tools, car battery checking, and fuel injector condition signs that may connect with DM303 diagnostic use cases. Guide / 10-28-2025A Simple Guide to Checking and Replacing Car Battery YourselfA car battery is the core component of a vehicle’s starting system. Essentially, it is a rechargeable DC power source that converts chemical energy into electrical. Guide / 12-10-2025See These Signs? Your Fuel Injectors Are Clean!Why is it necessary to assess the effectiveness of fuel injector cleaning? Fuel injector cleaning affects power, fuel efficiency, idle, and emissions; learn. Guide / 10-22-2025AUTOOL New Product Release | DM103 Digital LCR TweezerIn automotive circuit board testing, the loss factor D value is a key indicator reflecting the performance of capacitors. A smaller D value indicates lower loss and. Guide / 2025-10-22AUTOOL New Product Release | DM103 Digital LCR TweezerLearn the DM103 positioning, D/Q interpretation, and component-level testing workflow.Warranty And ContactWarranty And ContactFor DM303 battery setup, lithium charging confirmation, DM301 / DM303 model selection, test lead confirmation, injector test limits, K/CAN line data use, manual support, accessories, or warranty service, contact AUTOOL Store directly.Pre-Sales And Product SupportUse support if you need help confirming battery compatibility, charging rules, included accessories, language options, automotive circuit testing, analog signal output, injector / relay testing, or comparison with DM301 and other AUTOOL multimeters.3-year warranty for eligible non-human damage casesBattery type and lithium charging confirmationDM301 / DM303 model selection supportPackage contents and test lead confirmationInjector, relay, cranking, analog signal, and K/CAN function explanationManual download, setup guidance, and after-sales troubleshootingEmail Support[email protected] WhatsApp Support 86 189 2647 7404