1. Entwodiksyon
The AUTOOL DM303 is a hand-held, advanced diagnostic oscillometric multimeter designed for automotive applications. It integrates the functionalities of a digital oscilloscope and a digital multimeter, utilizing embedded digital control technology to provide comprehensive vehicle circuit testing and analysis. This manual provides detailed instructions for the proper use and maintenance of your DM303 device.

Figure 1: AUTOOL DM303 Auto Diagnostic Multimeter with included accessories.
2. Karakteristik kle
The AUTOOL DM303 offers a wide range of diagnostic and measurement capabilities:
- Multimeter Functions: DC/AC Voltage Measurement, DC/AC Current Measurement, Resistance Measurement, Frequency Measurement, Diode Test.
- Oscilloscope Test: Waveform analysis with 500KHz bandwidth and variable samplen frekans.
- Automotive Specific Tests: Automotive Circuit Test, Cranking Test, Injector Test, Relay Test, Analog Signal Test, Ignition Signal Test, K/CAN Line Data analysis.
- Ekspozisyon: 2.8-inch color LCD with 320*240 resolution and adjustable brightness.
- Sipò pou plizyè lang: English, Russian, French, Italian, German, Spanish, Portuguese, Polish, Dutch, Japanese, Korean, Chinese.
- Pòtabilite: Comes with a durable portable toolbox for easy storage and protection.
- Software Upgradable: Supports application software updates via SD card.

Figi 2: Plis paseview of the 12 test functions available on the DM303.
3. Pake kontni
The AUTOOL DM303 package includes the following items:
- AUTOOL DM303 Main Unit
- Bwat zouti pòtab
- Manyèl itilizatè
- Various Detection Lines and Probes:
| Non. | Non | Tèt Distribisyon No. | Fonksyon |
|---|---|---|---|
| 1 | Liy deteksyon milti-fonksyonèl | C01-1 | DC Connector, konekte ak liy clip batri a |
| C01-2 | Injector / relay test terminals | ||
| C01-K | K liy siyal liy | ||
| C01-CAN+ | CAN + liy siyal | ||
| C01-CAN- | CAN- liy siyal | ||
| C01-GND | Fil tè | ||
| C01-SIN | Liy siyal vag sinis | ||
| C01-S1 | Liy siyal 5V | ||
| C01-S2 | Liy siyal kare | ||
| 2 | Liy deteksyon sikwi otomobil | C02-1 | DC Connector, konekte ak liy clip batri a |
| C02-2 | Sonde tèminal | ||
| 3 | Ignition signal detection line | Inductive high-voltage siyal | |
| 4 | Liy clip batri | Konekte batri a | |
| 5 | Jumper (Yellow) | Connect multiple circuit connectors | |
| 6 | Jumper (Green) | Connect multiple circuit connectors | |
| 7 | Jumper (Black) | Connect multiple circuit connectors | |
| 8 | Sonde | Circuit measurement |

Figi 3: Detaye view of the various detection lines and their applications.
4. Pwodwi souview
Familiarize yourself with the components and controls of the AUTOOL DM303:

Figure 4: AUTOOL DM303 device layout and labeled parts.
- Ekspozisyon ekran
- Endikatè pouvwa
- Pouvwa kle
- Kenbe kle
- Kle direksyon
- Retounen kle
- Antre kle
- 10A aktyèl D '
- Antre mezi mA/uA
- Kle ekleraj
- ZERO / F1 Function key
- F2 Fonksyon kle
- Chanje mòd mezi
- Dyòd, voltage, rezistans, D' mezi frekans
- D' mezi COM
- DB15 koòdone
- SD card slot / data interface
- Limyè
- Support dèyè
5. Inisyal Enstalasyon
5.1 Enstalasyon batri
The DM303 is not equipped with batteries upon purchase. You will need to acquire 4x 1.5A batteries or a 3.7V, 1200 mAh lithium battery locally. Ensure correct polarity when installing batteries. The device will automatically turn off if disconnected from the charging cable without batteries installed.
5.2 Anviwònman Lang
The device supports multiple languages. To change the language:
- Pouvwa sou aparèy la.
- Navigate to the 'Basic Setting' menu using the direction keys.
- Select 'Language Setting' and choose your preferred language from the list (English, Russian, French, Italian, German, Spanish, Portuguese, Polish, Dutch, Japanese, Korean, Chinese).
- Konfime seleksyon ou a.

Figure 5: Language selection screen on the DM303.
5.3 Ajisteman klète ekran an
The 2.8-inch color display's brightness can be adjusted for optimal visibility in various working environments.
- Navigate to the 'Basic Setting' menu.
- Select 'Brightness' and adjust to your desired level.

Figure 6: Basic settings menu for screen brightness.
6. Operasyon Enstriksyon
The AUTOOL DM303 offers a variety of diagnostic modes. Select the appropriate mode from the main menu using the direction keys and 'OK' button.
Video 1: Demonstration of AUTOOL DM303 performing various diagnostic tests on a vehicle.
6.1 Multimeter Functions
Access the Multimeter mode to perform standard electrical measurements:
- VoltagMezi (DC/AC): Connect the probes to the circuit to measure voltage. The input impedance is 2~3MΩ for voltages below 160V and 10MΩ for voltagse pi wo a 160V.
- Mezi Kouran (DC/AC): Use the 10A terminal for currents up to 20A (protected by a 15A self-recovery fuse) or the mA/uA terminal for currents up to 200mA (protected by a 0.5A self-recovery fuse).
- Mezi rezistans: Measure the resistance of components.
- Mezi frekans: Determine the frequency of electrical signals.
- Tès dyòd: Check the functionality of diodes.
6.2 Oscilloscope Test
The Oscilloscope mode provides a comprehensive intelligent measurement system for signal analysis. It features a waveform test bandwidth of 500KHz and a variable sampling frequency, allowing for the measurement and observation of various automotive signals, including:
- Motor drive signals and motor power voltage in new energy vehicles.
- Fuel car engine ignition pulse signals.
- Camshaft and crankshaft signals.
- Wheel speed sensor signals.
- Oxygen sensor signals.
6.3 Automotive Circuit Test
This function allows for general testing of automotive circuits to identify faults.
6.4 Tès manivè
Perform a cranking test to assess battery and starter performance during engine startup. The device displays current, minimum voltage, and start voltage, comparing them against a minimum value of 9.6V.
6.5 Injector Test
Test the operation of fuel injectors by simulating engine speed (e.g., 1000 RPM) and checking the output signal.
6.6 Relay Test
Verify the functionality of automotive relays by checking their output status and contact resistance.
6.7 Analog Signal Test
Generate and test analog signals, including sine wave and square wave outputs, with adjustable frequency and duty cycle.
6.8 Ignition Signal Test
Analyze ignition pulse signals to diagnose ignition system issues.
6.9 K/CAN Line Data
Monitor and analyze K/CAN line data for communication diagnostics within the vehicle's network.

Figi 7: Egzamples of the DM303 interface display for different test functions.
7. Espesifikasyon
| Atribi | Spesifikasyon |
|---|---|
| Non modèl | DM303 |
| Non mak | AUTOOL |
| Ekspozisyon ekran | 2.8 inch LCD Color screen |
| Rezolisyon | 320 * 240 |
| Voltage Mezi Range | DC 0-1000V, AC 0-700V |
| Ranje Mezi aktyèl | 0-20A, 0-200mA |
| Ranje Mezi Rezistans | 0-1MΩ |
| Ranje Mezi Frekans | 1Hz-1MHz |
| Automotive Circuit Drive Current | 0-5A (Maximum Output) |
| Injector Drive Signal Output | 500-6000rpm |
| Max Antre Voltage (Oscilloscope) | 1000Vpp |
| Analog Bandwidth (Oscilloscope) | 500KHz |
| Input Impedance (Voltage Mezi) | 2~3MΩ (<160V), 10MΩ (>160V) |
| 10A Terminal Fuse | 15A pwòp tèt ou-rekiperasyon fuse |
| mA/uA Terminal Fuse | 0.5A pwòp tèt ou-rekiperasyon fuse |
| Tanperati travay | 0 ~ 40 ° C (32 ~ 104 ° F) |
| Travay imidite | ≤75% |
| Tanperati Depo | 10 ~ 50 ° C (14 ~ 122 ° F) |
| Depo Imidite | ≤70% |
| Altitid | 2000m |
| Pwa atik | 1.7kg |
| Dimansyon atik (L x W x H) | 26cm x 20cm x 11cm |
| Sètifikasyon Tès Ekstèn | CE |
| Orijin | Lachin tè pwensipal |

Figure 8: DM303 product dimensions and key specifications.
NAN. Depanaj
- Aparèy pa soumen: Ensure batteries are correctly installed and charged, or that the device is connected to a power source.
- Pa gen ekran oswa ekran an fèb: Adjust screen brightness in the 'Basic Setting' menu.
- Lekti ki pa kòrèk: Verify that the probes are correctly connected to the appropriate input terminals and that the correct measurement mode is selected. Check for damaged cables or probes.
- Difficulty with K/CAN line data: Ensure proper connection to the vehicle's K/CAN lines. Refer to the vehicle's service manual for specific wiring diagrams.
- Testing 24V circuits: The DM303 supports DC voltage measurement up to 1000V, so it is suitable for testing 24V circuits.
- Injector testing for high-pressure injectors: The Injector Test function provides signal output for injector operation. While it simulates engine speed (500-6000rpm), specific voltage requirements for high-pressure injectors (e.g., 75V) are not explicitly stated as a direct output capability. Always refer to the vehicle's specifications for compatibility.
9. Konsèy itilizatè yo
- Preparasyon batri: Remember that the DM303 does not include batteries. Purchase 4x 1.5A batteries or a 3.7V, 1200 mAh lithium battery before first use.
- Language Customization: Pran avantage of the multilingual support to set the device to your native language for easier operation.
- Mizajou lojisyèl: Regularly check the AUTOOL Official Store website for software updates. Updates can be installed via an SD card to ensure your device has the latest features and improvements.
- Jesyon kab: Utilize the provided portable toolbox to keep all cables and accessories organized and protected, extending their lifespan.
10. Antretyen
- Depo: Always store the DM303 and its accessories in the provided portable toolbox when not in use. This protects the instrument from physical damage due to falling or crashing.
- Kondisyon anviwònman: Operate the device within the specified working temperature of 0~40°C (32~104°F) and humidity ≤75%. For storage, maintain temperatures between 10~50°C (14~122°F) and humidity ≤70%.
- Netwayaj: Netwaye aparèy la avèk yon twal mou epi sèk. Pa sèvi ak pwodui netwayaj abrazif oswa solvan.
- Mizajou lojisyèl: Keep the device's software updated by downloading the latest versions from the AUTOOL website and installing them via an SD card.

Figure 9: The portable toolbox helps protect your DM303.
11. Garanti ak sipò
11.1 Enfòmasyon sou Garanti
All AUTOOL products purchased from an authorized AUTOOL store come with a 3-ane garanti. This warranty covers manufacturing defects and ensures the quality of your product.
11.2 Sipò teknik
AUTOOL Official Store provides lifetime technical support for the DM303. If you encounter any issues or have questions regarding the operation of your device, please contact our customer service. All emails will be answered within 24 hours.





