LANGUAGE & CURRENCY
AUTOOL DM303 Digital Multimeter Car Circuit Tester
US$190.00
Key Features
- K/CAN Test
- Oscilloscope Mode
- Injector Test
- K/CAN Test: Supports K/CAN signal testing alongside circuit diagnosis.
- Oscilloscope Mode: Built-in oscilloscope helps inspect live automotive signals.
- Injector Test: Covers injector, cranking, and analog signal checks in one unit.
- 3-Year Warranty Main unit 3 years · Accessories 1 year
- 90-Day Returns Eligible returns within 90 days
- Official Store Genuine products · Direct support
AUTOOL DM303
Product Overview
AUTOOL 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 Test
2.8-inchColor Display
DC 0-1000VVoltage Range
1Hz-1MHzFrequency Range
3 YearsWarranty
Click to enlargeBefore You Order And Use
Before You Order And Use
DM303 and DM301 are shipped without batteries. Confirm the battery type before use, and do not charge dry batteries inside the device.
Batteries Are Not Included
DM303 / DM301 is shipped without batteries due to shipping and battery restrictions. Batteries need to be purchased separately.
Dry Battery Option
You can install 4pcs 1.5V dry batteries for normal use. Do not charge dry batteries through the device.
Lithium Battery Option
You may install a compatible lithium battery by yourself. The reference image shows a 503450 3.7V 1000mAh lithium battery style.
Charge Only Lithium Setup
If a compatible rechargeable lithium battery is installed, it can be charged. Dry batteries must not be charged.
Battery Safety Reminder
- Do 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 Comparison
Product Comparison
DM303 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 Features
Key Features
DM303 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 Multimeter
Measures 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 Oscilloscope
The handheld oscilloscope supports 500kHz bandwidth and one-button automatic waveform display for observing slowly changing or automotive circuit signals.
Automotive Circuit Test
Supports 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 Test
During 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 Test
DM303 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 Data
Supports 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.
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Click to enlargeSpecifications
AUTOOL DM303 Product Specifications
DM303 supports wide voltage, current, resistance, and frequency ranges, plus automotive circuit drive current and injector drive signal output for vehicle electrical diagnosis.
| Core Specifications | |
| Product | AUTOOL DM303 Auto Diagnostic Multimeter |
| Display | 2.8-inch color screen |
| Voltage Measurement Range | DC 0-1000V, AC 0-700V |
| Current Measurement Range | 0-20A, 0-200mA |
| Resistance Measurement Range | 0-1MΩ |
| Frequency Measurement Range | 1Hz-1MHz |
| Automotive Circuit Drive Current | 0-5A |
| Injector Drive Signal Output | 500-6000rpm |
| Oscilloscope Bandwidth | 500kHz |
| Working Temperature | 0°C-40°C / 32°F-104°F |
| Power Supply Method | Dry battery, Type-C, 12V rechargeable battery configuration, and optional lithium battery setup depending on installation |
| Data Lock / Clear | Supported |
| Language Support | Multi-language interface including English, French, Portuguese, Polish, Spanish, Japanese, Russian, Italian, German, Dutch, Korean, Chinese, and other supported firmware options |
| Applicable Vehicle Models | Trucks, sedans, buses, electric vehicles, and other vehicle types |
| Warranty | 3-year support for eligible non-human damage cases |
| Product Structure | |
| Structure Overview | DM303 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 Keys | Display screen, power key, hold key, direction keys, return key, enter key, function keys, measurement mode switching, and lighting key. |
| Measurement Ports | 10A current input, mA / μA measurement input, COM measurement input, and diode / voltage / resistance / frequency measurement input. |
| Diagnostic Interfaces | DB15 interface, SD card slot / data interface, and back bracket for convenient display positioning during testing. |
| Toolbox | The plastic toolbox stores the main unit and accessories, helps protect the instrument, and makes it easier to carry to repair sites. |
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Click to enlargeCore Specifications
ProductAUTOOL DM303 Auto Diagnostic Multimeter
Display2.8-inch color screen
Voltage Measurement RangeDC 0-1000V, AC 0-700V
Current Measurement Range0-20A, 0-200mA
Resistance Measurement Range0-1MΩ
Frequency Measurement Range1Hz-1MHz
Automotive Circuit Drive Current0-5A
Injector Drive Signal Output500-6000rpm
Oscilloscope Bandwidth500kHz
Working Temperature0°C-40°C / 32°F-104°F
Power Supply MethodDry battery, Type-C, 12V rechargeable battery configuration, and optional lithium battery setup depending on installation
Data Lock / ClearSupported
Language SupportMulti-language interface including English, French, Portuguese, Polish, Spanish, Japanese, Russian, Italian, German, Dutch, Korean, Chinese, and other supported firmware options
Applicable Vehicle ModelsTrucks, sedans, buses, electric vehicles, and other vehicle types
Warranty3-year support for eligible non-human damage cases
Product Structure
Structure 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 Box
What Is In The Box
The 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 multimeter
StoragePortable protective toolbox and retail box
DocumentationUser manual shown in the package image
Test LeadsMultifunction test lead, battery clip cable, multimeter probes, jumper / adapter cables, and additional test leads shown in the package image
Battery NoticeBatteries are not included. Use 4pcs 1.5V dry batteries or a compatible lithium battery setup according to the battery rules.
Related Products
Related Products
Compare DM303 with related AUTOOL multimeter options before choosing a professional automotive diagnostic multimeter or a smaller general-purpose digital multimeter.
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Manual And Downloads
Manual And Downloads
Download the DM303 manual for battery setup, test modes, wiring, interface operation, and safe-use guidance.
Click to enlargeAUTOOL DM303 Manual PDF
Open 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.
Questions And Answers
These 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.
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.
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.
The reference image shows a 503450 3.7V 1000mAh lithium battery style. Confirm the connector, size, and compatibility before installing a lithium battery.
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.
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.
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.
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.
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.
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.
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.
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 Guides
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Warranty And Contact
Warranty And Contact
For 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 Support
Use 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 cases
- Battery type and lithium charging confirmation
- DM301 / DM303 model selection support
- Package contents and test lead confirmation
- Injector, relay, cranking, analog signal, and K/CAN function explanation
- Manual download, setup guidance, and after-sales troubleshooting
Customer Reviews
Leave A Review
Schaffler H.W Jean Louis ✓ Verified Purchase –
Good product
Item received as discribed and descriptions are match to what I received.
I will recommend this product.
Jannette Wilmes ✓ Verified Purchase –
Goooooood
Great quality, matches the picture, fast shipping!
Temmink ✓ Verified Purchase –
The features are comprehensive!
The features are comprehensive! Great tool!