UNI-T UT108 Operating Manual
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UNI-T UT108 Operating Manual

Handheld automotive multi-purpose meters
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P/N:110401102526

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Summary of Contents for UNI-T UT108

  • Page 1 P/N:110401102526...
  • Page 2 UT108/109 Handheld Automotive Multi-Purpose Meters Operating Manual...

  • Page 3: Table Of Contents

    UT108/109 OPERATING MANUAL Table of Contents Title Page Overview Unpacking Inspection Safety Information Rules for Safe Operation Automotive Servicing Safety Guide International Electrical Symbols The Meter Structure Rotary Switch Functional Buttons Display Symbols Measurement Operation Part 1 Multimeter Basic Testing AC/DC Voltage Testing B.
  • Page 4 UT108/109 OPERATING MANUAL Title Page Diode Testing G. Capacitance Testing H. Frequency Testing Temperature Measurement (UT109 only) Dwell Testing K. Engine Tach (Rotation Speed) Testing “RPMx10” Operation of Hold Mode M. RANGE button N. MAX MIN button O. Data Outputting Display backlight Q.
  • Page 5 UT108/109 OPERATING MANUAL Title Page E. Battery Power Consumption Testing when the Engine Is off Trigger Voltage Battery Load Testing G. Voltage Drop Testing H. Charging System Voltage Testing Ignition System Testing Ignition Coil Testing Ignition System High Voltage Damper Testing...
  • Page 6 UT108/109 OPERATING MANUAL Title Page General Specifications Accurate Specifications DC Voltage B. AC Voltage C. DC millvoltage AC Current E. DC Current Resistance G. Capacitance H. Frequency Diode Continuity Dwell Tach (Rotation Speed) M. Temperature Maintenance General Services B. Replacing the Fuses...

  • Page 7: Overview

    To avoid electric shock or personal injury, read the “Safety Information” and “Rules for Safe Operation” carefully before using the Meter. Automotive Digital Multimeter Model UT108/UT109 (hereafter referred to as “the Meter”) is a 4000 counts, 3-3/4 digits manual ranging meter. The meter uses large scale of integrated circuit with integrated A/D converter as its core.

  • Page 8: Unpacking Inspection

    UT108/109 OPERATING MANUAL Unpacking Inspection Open the package case and take out the Meter. Check the following items carefully to see any missing or damaged part: Item Description English Operating Manual 1 piece Test Lead 1 pair K-Type Point Contact Temperature Probe.

  • Page 9: Safety Information

    UT108/109 OPERATING MANUAL Safety Information This Meter complies with standards IEC61010: in pollution degree 2, overvoltage category (CATIII 1000V, CATⅣ 600V) and double insulation. CAT III: Distribution level, fixed installation, with smaller transient overvoltages than CAT CAT IV: Primary supply level, overhead lines, cable systems ets.

  • Page 10: Rules For Safe Operation

    UT108/109 OPERATING MANUAL Rules For Safe Operation Warning To avoid possible electric shock or personal injury, and to avoid possible damage to the Meter or to the equipment under test, adhere to the following rules: ● Before using the Meter inspect the case. Do not use the Meter if it is damaged or the case (or part of the case) is removed.
  • Page 11 UT108/109 OPERATING MANUAL Meter. ● Disconnect circuit power and discharge all high-voltage capacitors before testing, resistance, diodes or continuity. ● Before measuring current, check the fuse is ok. Before connecting the Meter in serial to the tested in-circuit, disconnect in-circuit power.

  • Page 12: Automotive Servicing Safety Guide

    UT108/109 OPERATING MANUAL deteriorate after dampened. ● The Meter is suitable for indoor use. Automotive Servicing Safety Guide Warning As some automobiles are installed with safety air bags, you must pay attention to the cautions in the automotive servicing manual when you are working around the components and wiring of the air bags, or any carelessness will open an air bag, resulting in some personal injury.
  • Page 13 UT108/109 OPERATING MANUAL operating engine. ● Ensure that the automobile has stopped (automatic transmission) or put into neutral gear (manual transmission) and be sure that it is equipped with brakes and the wheels have been locked. ● Do not place any tool on the automotive battery which will cause a short circuit of the electrodes and in turn lead to any personal injury or damage to a tool or battery.
  • Page 14 UT108/109 OPERATING MANUAL 2. Contact the local retailers of automotive components. 3. Contact the local libraries to look up any book for the proofreading of your automotive servicing manual so as to provide you with the latest information. B.before the diagnosis of any trouble opens the engine hood to make a thorough visual inspection.

  • Page 15: International Electrical Symbols

    UT108/109 OPERATING MANUAL International Electrical Symbols AC (Alternating Current). DC (Direct Current) Grounding. AC or DC Diode Double Insulated. Deficiency of Built-In Battery. Fuse. Warning. Refer to the Operating Manual. Conforms to Standards of European Union.

  • Page 16: The Meter Structure

    UT108/109 OPERATING MANUAL The Meter Structure (see figure 1) 1. LCD display 2. Functional buttons 3. SELECT button 4 Power button 5 Rotary Switch 6 Input Terminals (Figure 1)

  • Page 17: Rotary Switch

    UT108/109 OPERATING MANUAL Rotary Switch Below table indicated for information about the rotary switch positions. AC or DC Voltage Measurement. millvoltage Measurement. ℃ The unit of temperature, ℃: Centigrade temperature (UT109 only) ℉ The unit of temperature, ℉: Fahrenheit temperature (UT109 only) Ω...

  • Page 18: Functional Buttons

    UT108/109 OPERATING MANUAL Functional Buttons (see figure 2) Below table indicated for information about the functional button operations Figure 2...
  • Page 19 UT108/109 OPERATING MANUAL Button Operation Performed Turn the power on and off. Press HOLD once to enter hold mode. ● HOLD/ ● Press HOLD again to exit hold mode and the present value is shown. ● Press and hold for 2 seconds to turn the display backlight on or off.

  • Page 20: Display Symbols

    UT108/109 OPERATING MANUAL Display Symbols (see figure 3) Figure 3...
  • Page 21 UT108/109 OPERATING MANUAL Data output is in progress. The battery is low. Warning: To avoid false readings, which could lead to possible electric shock or personal injury, replace the battery as soon as the battery indicator appears. maximum or minimum reading displayed...

  • Page 22: Measurement Operation

    UT108/109 OPERATING MANUAL Measurement Operation Part 1 Multimeter Basic Testing A. AC/DC Voltage Testing (see figure 4) Warning To avoid harms to you or damages to the Meter from electric shock, please do not attempt to measure voltages higher than 1000Vp although readings may be obtained.
  • Page 23 UT108/109 OPERATING MANUAL Note ● If the value of voltage to be measured is unknown, use the maximum measurement position (1000V) and reduce the range step by step until a satisfactory reading is obtained. ● Please take extra care when measuring high voltages to avoid electric shock.
  • Page 24 UT108/109 OPERATING MANUAL Figure 4...

  • Page 25: Dc Millvoltage Testing

    UT108/109 OPERATING MANUAL B. DC millvoltage Testing (see figure 5) Warning To avoid harms to you or damages to the Meter from electric shock, please do not attempt to measure voltages higher than the range although readings may be obtained.
  • Page 26 UT108/109 OPERATING MANUAL Figure 5...

  • Page 27: Ac/Dc Current Testing

    UT108/109 OPERATING MANUAL C. AC/DC Current Testing (see figure 6) Warning Before connecting the Meter in serial to the tested in-circuit, disconnect in-circuit power. If the fuse burns out during measurement, the Meter may be damaged or the operator himself may be hurt.
  • Page 28 UT108/109 OPERATING MANUAL 4. Connect the test leads across with the object being measured. The measured value shows on the display. Note ● If the value of current to be measured is unknown, use the maximum measurement position 10A terminal, and reduce the range step by step until a satisfactory reading is obtained.
  • Page 29 UT108/109 OPERATING MANUAL Figure 6...

  • Page 30: Resistance Testing

    UT108/109 OPERATING MANUAL D. Resistance Testing (see figure 7) Warning To avoid damages to the Meter or to the devices under test, disconnect circuit power and discharge all the high-voltage capacitors before measuring resistance. To avoid harm to yourselves, never attempt to input an effective voltage over 60V in DC or 30V in AC.
  • Page 31 UT108/109 OPERATING MANUAL reading, and it is better to choose shorter test lead. ● When resistance measurement has been completed, disconnect the connection between the testing leads and the circuit under test. Figure 7...

  • Page 32: Continuity Testing

    UT108/109 OPERATING MANUAL E. Continuity Testing (see figure 8) Warning To avoid possible damage to the Meter and to the device under test, disconnect circuit power and discharge all high-voltage capacitors before testing diodes and continuity. To avoid harm to yourselves, never attempt to input an effective voltage over 60V in DC or 30V in AC.
  • Page 33 UT108/109 OPERATING MANUAL good condition. 4. The nearest value of the tested circuit show on the display, the unit is Ω. Note ● Open-circuit voltage is approx. 3V. ● When continuity testing has been completed, disconnect the connection between the...
  • Page 34 UT108/109 OPERATING MANUAL Figure 8...
  • Page 35 UT108/109 OPERATING MANUAL F. Diode Testing (see figure 9) Warning To avoid possible damage to the Meter and to the device under test, disconnect circuit power and discharge all high-voltage capacitors before testing diodes and continuity. To avoid harm to yourselves, never attempt to input an effective voltage over 60V in DC or 30V in AC.
  • Page 36 UT108/109 OPERATING MANUAL Note ● In a circuit, a good diode should still produce a forward voltage drop reading of 0.5V to 0.8V; However, the reverse voltage drop reading can vary depending on the resistance of other pathways between the probe tips.
  • Page 37 UT108/109 OPERATING MANUAL Figure 9...
  • Page 38 UT108/109 OPERATING MANUAL G. Capacitance Testing (see figure 10) Warning To avoid damage to the Meter or to the equipment under test, disconnect circuit power and discharge all high-voltage capacitors before measuring capacitance. To measure capacitance, connect the Meter as follows: 1.
  • Page 39 UT108/109 OPERATING MANUAL Figure 10...
  • Page 40 UT108/109 OPERATING MANUAL H. Frequency Testing (see figure 11) To measure frequency, connect the Meter as follows: 1. Insert the red test lead into the Hz terminal and the black test lead into the COM terminal. 2. Under AC/DC voltage, DC millvoltage or AC/DC current measurement, press Hz button to select frequency measurement mode, the measured value shows on the display.
  • Page 41 UT108/109 OPERATING MANUAL Figure 11...
  • Page 42 UT108/109 OPERATING MANUAL I. Temperature Measurement (UT109only)(See figure 12) Warning To avoid harm to yourself, do not input higher than DC 60V or AC 30V voltages. To measure temperature, connect the Meter as follows: 1. Set the rotary switch to ℃℉. Press BLUE button to select temperature measurement mode.
  • Page 43 UT108/109 OPERATING MANUAL Figure 12...
  • Page 44 UT108/109 OPERATING MANUAL J. Dwell Testing (see figure 13) It was very important in the past to test the dwell of the cut-off switch of an ignition system. The dwell testing means the duration when the cut-off switch remains off when the cam is turning.
  • Page 45 UT108/109 OPERATING MANUAL Figure 13...
  • Page 46 UT108/109 OPERATING MANUAL . Engine Tach (Rotation Speed) Testing “RPMx10” (see figure 14) The RPM means the rotating frequency of the main shaft of the engine per minute. 1. Set the rotary switch to RPM X10 DWELL. Press RANGE button to select the number of cylinders and press BLUE button to select RPM X10 measurement mode.
  • Page 47 UT108/109 OPERATING MANUAL RPM (200 x 10) if the displayed value is 200 and the meter is set at the 6CYL (6 cylinders) notch. Figure 14...
  • Page 48 UT108/109 OPERATING MANUAL L. Operation of Hold Mode The Hold mode is applicable to all measurement functions: ● Press HOLD to enter Hold mode ● Press HOLD again to exit Hold mode ● In Hold mode, is displayed M. RANGE button Press RANGE to enter the manual ranging mode;...
  • Page 49 UT108/109 OPERATING MANUAL present measurement range. O. Data Outputting ● Press and hold Hz button for over 2 seconds to enter or exit RS232C or USB mode. ● The sleep mode feature will be disabled after entering RS232C or USB mode.
  • Page 50 UT108/109 OPERATING MANUAL Part 2 Diagnosis of Automotive Troubles The Meter is a tool for the very effective diagnosis of the troubles with the electronic systems of the automobile. This part gives a special introduction as to how the Meter is used to diagnose any trouble with a fuse, switch, solenoid, relay, starting and charging systems, ignition system, fuel system and engine sensor.
  • Page 51 UT108/109 OPERATING MANUAL B. Switch Testing: Check the switch to see if it can work correctly. 1. The same as in Items 1 to 3 (Fuse Testing). 2. Connect the black test lead probe to one end of the switch and the red one to another end.
  • Page 52 UT108/109 OPERATING MANUAL D. Starting/Charging System Testing The on-off package of the engine starting system consists of a battery, engine starting button, solenoid and relay starting buttons, lead connections and lines. During the operation of the engine, the charging system keeps the battery charged. This system consists of an AC generator, voltage calibrator, lead connections and circuits.
  • Page 53 UT108/109 OPERATING MANUAL 12.60 V 100% 12.45 V 12.30 V 12.15 V E. Battery Power Consumption Testing when the Engine is off The test is carried out to find the amperage of the power consumption of the battery when both the ignition key and the engine are off. The test is helpful for the determination of the additional consumption of the battery, which may finally lead to the exhaustion of the battery.
  • Page 54 UT108/109 OPERATING MANUAL Warning: Do not start the engine of the automobile in testing, or the meter will be damaged. 4. Read the reading of the tested current directly from the display with the normal current being about 100mA. For the special supply of currents (when the engine is off), please refer to the automotive servicing manual.
  • Page 55 UT108/109 OPERATING MANUAL the positive pole of the battery. 5. Start the engine continuously for 15 seconds and the testing results are shown in contrast as follows. If it is within the range, the starting system is normal; on the...
  • Page 56 UT108/109 OPERATING MANUAL G. Voltage Drop Testing Test the voltage drops caused by the switch, cable, solenoid or connector. Any abnormal voltage drop generally results from an additional resistance. The resistance will restrict the currents upon the start of the engine, leading to the reduction of the load voltage of the battery and the slow-down of the start of the engine.
  • Page 57 UT108/109 OPERATING MANUAL Compare the readings of the tested voltages against the said table. If the voltage is on the high side, check the components and connectors to see if there is anything wrong. If anything wrong is found, do necessary servicing.
  • Page 58 UT108/109 OPERATING MANUAL H. Charging System Voltage Testing This testing is used to see if the charging system operates normally so as to provide the electronic systems with adequate power (lamps, electric fans, radio sets, etc.). 1. Set the rotary switch to the DCV. Insert the red test lead into the A terminal and the black one into the COM terminal.
  • Page 59 UT108/109 OPERATING MANUAL I. Ignition System Testing 1.Ignition Coil Testing (1) Before the operation, cool the engine and cut off the ignition coil. (2) Set the rotary switch to the Ω. Insert the red test lead into the Ω terminal and the black one into the COM terminal.
  • Page 60 UT108/109 OPERATING MANUAL (7) The primary resistance is generally in a range of 6 kΩ to 30 kΩ. Refer to various kinds of automotive manuals for the details. (8) For a heater ignition coil, repeat the said testing steps. Warning: For a heater ignition coil, the resistance may be a little higher because the resistance of a coil will vary with the temperatures.
  • Page 61 UT108/109 OPERATING MANUAL Figure 16...
  • Page 62 UT108/109 OPERATING MANUAL 2. Ignition System High-Voltage Damper Testing (see figure 17) (1) Move the connectors of the ignition system from the engine. Refer to the ignition system movement procedure in various kinds of automotive manuals for the details. Warning: Some of Chrysler’s products use a spark plug high voltage damper with “positive...
  • Page 63 UT108/109 OPERATING MANUAL Figure 17...
  • Page 64 UT108/109 OPERATING MANUAL 3. Hall Switch/Sensor Testing (see figure 18) When the tach and dwell are tested in the computer of the automobile, a Hall sensor is used. The Hall sensor is normally used in the ignition system to detect the position of the camshaft so that the computer of the automobile can set the optimal time for the ignition and the opening of the fuel injector.
  • Page 65 UT108/109 OPERATING MANUAL Figure 18...
  • Page 66 UT108/109 OPERATING MANUAL 4.Magnetic Resistance Sensor (see figure 19) The functions of a magnetic resistance sensor is similar to those of a Hall sensor and the testing methods of both sensors are also similar. Their normal resistance is generally in a range of 150 Ω...
  • Page 67 UT108/109 OPERATING MANUAL 5. RPM Testing (see figure 20) (1) Set the rotary switch to RPMx10 and select the number of cylinders in the automobile to be tested. (2) Insert the red test lead into the terminal and the black one into the COM terminal.
  • Page 68 UT108/109 OPERATING MANUAL Figure 20...
  • Page 69 UT108/109 OPERATING MANUAL 6.Fuel System Testing It is necessary to add more accurate engine fuel control to a low injection automobile. Since 1980, the automotive manufacturing industry has used electronically-controlled carburetor and fuel injection so as to achieve lower fuel injection.
  • Page 70 UT108/109 OPERATING MANUAL general normal resistance is less than or equal to 10 Ω. Figure 21...
  • Page 71 UT108/109 OPERATING MANUAL J.Engine Sensor Testing (see figure 22) To be adapted to the provisions for low injection and fuel saving in the early period of the eighties, the computer-controlled regulators were installed in the automobile and the sensors provided the computer with some data required. The Meter is an effective tool for the detection of the operation of a sensor.
  • Page 72 UT108/109 OPERATING MANUAL 1. Oxygen Sensor The oxygen sensor is used to test the oxygen content in the exhaust, giving rise to an appropriate voltage or resistance. A low voltage (high resistance) means too high oxygen content in the exhaust, while a high voltage (low resistance) means too low oxygen content.
  • Page 73 UT108/109 OPERATING MANUAL If the sensor has more than 3 leads, what is used in the automobile is a heat oxygen sensor, which has 2 hot ends. Refer the positions of the hot ends in various kinds of automotive manuals. At this time, connect the red and black test lead probes respectively to these two hot ends.
  • Page 74 UT108/109 OPERATING MANUAL 2.Temperature Sensor (see figure 23) The temperature sensor changes the output resistance through the changes in peripheral temperatures. The hotter the sensor is, the lower the resistance becomes.The temperature sensor is generally used in engine braking, air ventilation, flow, fuel temperature and other equipment.
  • Page 75 UT108/109 OPERATING MANUAL Testing Procedure: (1) The same as in the resistance testing method. (2) When the general temperature of a heating sensor rises, its resistance will drop. The thermal resistance of the temperature sensor of the automotive engine is generally less than 300 z.
  • Page 76 UT108/109 OPERATING MANUAL Figure 24...
  • Page 77 UT108/109 OPERATING MANUAL 4.Absolute Pressure (MAP) and Baro Sensor (see figure 25) The MAP sensor is used to change a pressure signal into a DC voltage or frequency one. All GM, Chrysler, Honda and Toyota use DC voltage type MAP sensors, while Ford uses frequency type MAP sensors.
  • Page 78 UT108/109 OPERATING MANUAL be based on the parameters furnished by the supplier.) Warning: RPM =Frequency × 120/ the number of cylinders.
  • Page 79 UT108/109 OPERATING MANUAL Figure 25 Figure 26...
  • Page 80 UT108/109 OPERATING MANUAL 5. Mass Air Flow (MAF) Sensor (see figure 26) The sensor converts the air flow into a DC voltage, low frequency or high frequency signal. The Meter can only be used to test a DC voltage or low frequency signal.
  • Page 81 UT108/109 OPERATING MANUAL General Specifications ● Maximum Voltage between any Terminals and grounding: Refer to different range input protection voltage. ● Fuse Protection of μA mA terminal: 1A, H 240V, fast type, φ6x25mm ● Fuse Protection of A terminal: 10A,H 240V, fast type, φ6x25mm ●...
  • Page 82 UT108/109 OPERATING MANUAL ● Electromagnetic Compatibility: EN61326-1:2006, EN61326-2:2006 ● Battery Type: One piece of 9V (NEDA1604 or 6F22 or 006P). ● Dimensions (HxWxL): 180 x 87 x 47mm. ● Weight: 370g. (including holster and battery) ● Safety/Compliances: IEC61010: CATIII 1000V, CATⅣ 600V overvoltage and double insulation standard.
  • Page 83 UT108/109 OPERATING MANUAL Accurate Specifications Accuracy: ± (a% Reading + Digits), guarantee for 1 year. Operating Temperature: 18℃ to 28℃. Relative Humidity: No more than 75% RH. A. DC Voltage Range Resolution Accuracy Overload Protection Input impedance 1 mV ± (0.5%+3) Around 10MΩ...
  • Page 84 UT108/109 OPERATING MANUAL Remarks: ● Input impedance: Around 10MΩ. ● Overload Protection: 1000V DC or AC ● Displays effective value of sine wave (mean value response)(10%~100% of the range) C. DC millvoltage Range Resolution Accuracy Overload Protection Input impedance 40mV 0.01 mV...
  • Page 85 UT108/109 OPERATING MANUAL Remarks: ● When measuring 5 to 10A: For continuous measurement ≤10 seconds and interval time between 2 measurement greater than 15 minutes. E. AC Current Range Resolution Accuracy(40Hz ~ 400Hz) Accuracy(400Hz ~ 1kHz) 400μA 0.1μA ± (1.2%+5) ±...
  • Page 86 UT108/109 OPERATING MANUAL For continuous measurement ≤10 seconds and interval time between 2 measurement greater than 15 minutes. F. Resistance Range Resolution Accuracy Overload Protection 400Ω 0.1Ω 4kΩ 1Ω 40kΩ 10Ω ± (1%+5) 500Vp 400kΩ 100Ω 4MΩ 1kΩ 40MΩ 10kΩ...
  • Page 87 UT108/109 OPERATING MANUAL H. Frequency Range Accuracy 10Hz~1MHz ± (0.1%+4) Overload Protection: the same as AC/DC voltage, DC millvoltage, AC/DC Current, and RPM mode. Input Amplitude: a 1) AC/DC voltage mode, When 40Hz ~ 1KHz: a ≥range x 10% (except 1000V range) a ≥400V (1000V range)
  • Page 88 UT108/109 OPERATING MANUAL I. Diode Range Resolution Overload Protection 500Vp Remarks: ● Open circuit voltage approximate 3V. ● The silicon PN junction normal voltage is about 500 mV to 800 mV. J. Continuity Testing Range Resolution Overload Protection 0.1Ω 500Vp Remarks: ●...
  • Page 89 UT108/109 OPERATING MANUAL K.Dwell Testing Range Resolution Accuracy Overload Protection 4CYL 6CYL 0.1° ± (3%+5) 500 Vp 8CYL Remark: ● Input Scope: ≥10V in forward impulse; Bandwidth ≥ 0.5mS L. Tach (Rotation Speed) Testing Range Resolution Accuracy Overload Protection 4CYL...
  • Page 90 UT108/109 OPERATING MANUAL Bandwidth ≥ 0.5mS ● Maximum Tach: 10000 RPM, Tach = Displayed Reading x 10. M. Temperature (UT109 only) Range Resolution Accuracy Overload Protection -400C ~ 537℃ 1℃ ±(1%+10) 500 Vp -400F ~ 998℉ 2℉ ± (1%+18)

  • Page 91: Maintenance

    UT108/109 OPERATING MANUAL Maintenance This section provides basic maintenance information including battery and fuse replacement instruction. Warning Do not attempt to repair or service your Meter unless you are qualified to do so and have the relevant calibration, performance test, and service information.

  • Page 92: Replacing The Fuses

    UT108/109 OPERATING MANUAL B. Replacing the Fuses (see figure 27) Warning To avoid electrical shock or arc blast, or personal injury or damage to the Meter, use specified fuses ONLY in accordance with the following procedure. To replace the Meter’s fused: 1.
  • Page 93 UT108/109 OPERATING MANUAL Figure 27...

  • Page 94: Replacing The Battery

    UT108/109 OPERATING MANUAL C. Replacing the Battery (see figure 27) Warning To avoid false readings, which could lead to possible electric shock or personal injury, replace the battery as soon as the battery indicator “ ” appears. To replace the Meter’s battery: 1.

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