Automotive multimeter Rexant 16-0102 is a universal device for diagnosing electrical circuits, which will be useful for both professional auto electricians and car owners who prefer to do their own repairs. It can be used to measure voltage, current, resistance, check diodes and circuits for open circuits, and also test the battery and generator. However, without understanding the operating principles and features of the device, even such a functional tester may be useless.

In this article we will look at not only the basic functions Rexant 16-0102, but also nuances that are rarely mentioned in standard instructions: how to correctly connect probes for accurate measurements, what modes to use to diagnose specific car components (for example, sensors or relays), and also how to avoid mistakes that lead to incorrect readings or even failure of the device. We will pay special attention to practical examples - from checking the battery charge to finding a short circuit in the wiring.

Contents and appearance: what is included in the set and how not to confuse the connectors

Comes as standard Rexant 16-0102 includes:

  • πŸ”§ Main unit of the multimeter with LCD display and rotary mode switch.
  • πŸ”Œ Two probes: red (positive) and black (negative) with ~1 meter long wires.
  • πŸ”‹ Protective cover or case (depending on the delivery version).
  • πŸ“„ Brief instructions in Russian (often with minimal description).

On the front panel of the device there are:

  • πŸ”„ Rotary mode switch with labels: OFF, DCV (constant voltage), ACV (alternating voltage), DCA (direct current), Ξ© (resistance), β†’β”‚( (dialing), hFE (checking transistors).
  • πŸ”Œ Three connectors for connecting probes: COM (general), VΞ©mA (voltage/resistance/current up to 200 mA), 10ADC (current up to 10 A).
  • πŸ“Š LCD display with backlight (in some modifications) and low battery indication.
⚠️ Attention: Never connect the red probe to the connector 10ADC when measuring voltage or resistance! This will cause the fuse inside the device to burn out. For most vehicle measurements, use the connector VΩmA.

On the back of the case are usually located:

  • πŸ”‹ Battery compartment 9V (Krona type).
  • πŸ”§ Cover for replacing the fuse (usually on 200 mA and 10 A).
  • πŸ“Œ Stand for vertical placement of the device on the table.
πŸ“Š What do you most often use an autotester for?
Battery check
Generator diagnostics
Finding breaks in wiring
Checking the sensors
Other

Preparing for work: checking the device and setting up before diagnostics

Before first use Rexant 16-0102 follow these steps:

  1. Check the battery. Install a new battery 9V (even if the device turns on, a weak battery may give inaccurate readings). When discharged, the icon will appear on the display BAT.
  2. Inspect the probes. Make sure the wires are not damaged and the terminals are clean and fit snugly. Oxidized probes can distort readings.
  3. Check fuses. Open the cover on the rear panel and make sure that both fuses (on 200 mA and 10 A) are intact. If necessary, replace them with similar ones at nominal value.
  4. Set the switch to position OFF. This will prevent the device from being turned on accidentally during transport.

For calibration (if the device gives inaccurate readings):

  • πŸ”„ Turn the switch to mode Ξ© (resistance).
  • πŸ”Œ Connect the probes with each other. The display should show a value close to 0 ohm (tolerance: Β±0.2 Ohm).
  • πŸ”§ If the readings are different, adjust the device using a potentiometer (if provided in your model).
⚠️ Attention: If, when connecting probes in mode Ω display shows 1 (infinity), this means a break in the wires or a malfunction of the device. Do not use such a multimeter for diagnostics!

β˜‘οΈ Preparing Rexant 16-0102 for work

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Voltage Measurement: Battery and Alternator Test

One of the most popular modes Rexant 16-0102 β€” DC voltage measurement (DCV). You can use it to check:

  • πŸ”‹ Battery charge (normal: 12.6–14.4 V with the engine running).
  • πŸ”„ Generator voltage (must be 13.8–14.4 V at idle).
  • πŸ’‘ Voltage in the on-board network (for example, at the cigarette lighter or fuse terminals).

Step-by-step instructions for checking the battery:

  1. Turn off the car's ignition.
  2. Connect the black probe to COM, red - to VΞ©mA.
  3. Set the switch to position 20V in the sector DCV.
  4. Touch the red probe to + battery terminal, black - to βˆ’.
  5. Take readings:
    • 12.6 V and above β€” the battery is 100% charged.
    • 12.0–12.5 V β€” partial discharge (recharging is recommended).
    • 11.5 V and below - deep discharge, charger required.

To check the generator:

  1. Start the engine and let it idle for 5-10 minutes.
  2. Connect the probes to the battery terminals (as in the previous paragraph).
  3. Normal Voltage: 13.8–14.4 V. If the value is lower 13.5 V β€” the generator undercharges the battery, if higher 14.7 V - overcharging is in progress (risk of electrolyte boiling away).
    4. Indications (B) Battery condition Actions
    12.6–14.4 Norm No need to recharge
    12.0–12.5 Partial discharge Recharging recommended
    11.5–12.0 Deep discharge Low current charging (2–3 A)
    <11.5 Critical discharge Battery restoration or replacement
    πŸ’‘

    If, when checking the generator, the voltage β€œfloats” (for example, jumps from 13.2 V to 14.8 V), this may indicate a malfunction of the relay regulator or wear of the generator brushes.

    Continuity testing: how to find an open or short circuit

    Call mode (β†’β”‚() allows you to check the integrity of wires, fuses and other circuit elements. This mode is indispensable for:

    • πŸ”Œ Search for breaks in wiring (for example, in door harnesses or under the hood).
    • πŸ” Checking fuses without removing them.
    • πŸ’‘ Diagnostics of lamps, relays and buttons.

How to ring a chain:

  1. Connect the probes: black - COM, red - VΞ©mA.
  2. Set the switch to mode β†’β”‚(.
  3. Touch the probes to the two ends of the circuit being tested:
    • πŸ”Š Beep and the value is close to 0 ohm - the chain is OK.
    • 1 the display shows a break.
    • Meaning <10 Ohm β€” high resistance (possible corrosion or poor contact).

Application examples:

  • πŸš— Checking the fuse: Touch the fuse legs with the probes. If a signal is heard, the fuse is intact. If not, it burned out.
  • πŸ”¦ Lamp diagnostics: Connect the probes to the lamp base. A working lamp will show resistance 0.5–3 Ohm (depending on power).
  • πŸ”Œ Finding a short circuit: Disconnect the wire being tested from the power source and test it to ground. If a signal is heard, there is a short circuit.
⚠️ Attention: Before testing, be sure to turn off the power to the circuit (remove the terminal from the battery or remove the fuse)! Measuring under voltage in the continuity mode can damage the device.
What should I do if the multimeter shows β€œ1” when dialing?

This means that the circuit resistance exceeds the measurement limit (typically >1 MΞ©). Possible reasons:

- Wire break.

- Oxidized contacts (clean them with sandpaper or WD-40).

- Incorrect connection of the probes (check that the red probe is in the VΞ©mA connector).

- Malfunction of the device itself (try ringing a wire that is known to be good).

Current measurement: diagnostics of consumers and leaks

Current measurement mode (DCA) allows you to determine how much energy a particular element of the car consumes. This is useful for:

  • πŸ”‹ Leakage current checks (standard: <50 mA with the ignition off).
  • πŸ’‘ Diagnostics of powerful consumers (starter, cooling fan).
  • πŸ”Œ Assessment of the performance of relays and electric motors (for example, window lifts).

How to measure leakage current:

  1. Turn off the ignition, remove the key from the lock, and close all doors.
  2. Disable βˆ’ battery terminal.
  3. Connect the red probe to 10ADC, black - to COM.
  4. Set the switch to 10A in the sector DCA.
  5. Connect the red probe to βˆ’ battery terminal, black - to the removed wire.
  6. Take readings:
    • <50 mA - the norm.
    • 50–100 mA β€” increased consumption (perhaps one of the units is faulty, for example, an alarm system).
    • >100 mA - critical leak, search for the cause is required.

How to measure consumer current (for example, starter):

  1. Connect the probes to an open circuit (for example, between + battery terminal and starter wire).
  2. Set the switch to 10A.
  3. Have an assistant turn the ignition key to the Start position.
  4. Normal starting current: 150–300 A (short term). If the value is lower 100 A, the starter brushes may be worn out or the battery may be discharged.
    5. ⚠️ Attention: When measuring high currents (more than 5 A), always use the connector 10ADC! Connection to VΩmA will cause the fuse to blow.
    πŸ’‘

    If, when measuring leakage current, the readings β€œfloat” (for example, jump from 20 mA to 80 mA), this may indicate an intermittently switched on unit (for example, an immobilizer or climate control). In this case, check each unit individually by removing the fuses.

    Resistance check: diagnostics of sensors and ignition coils

    Mode Ξ© allows you to evaluate the condition of sensors, ignition coils, generator windings and other elements with a fixed resistance. For example:

    • πŸ“Š Coolant temperature sensor (DTOZH): 2–5 kOhm at 20Β°C.
    • πŸ”₯Ignition coil: 0.5–2 Ohm (primary winding), 5–15 kOhm (secondary).
    • πŸ”‹ Generator winding: 0.2–0.5 Ohm (rotor), 0.1–0.3 Ohm (stator).

How to check the sensor:

  1. Disconnect the sensor connector.
  2. Connect the probes to the sensor terminals (polarity is not important).
  3. Compare the readings with the reference ones (see table below).
Sensor Normal resistance Reason for deviations
DTOZH (20Β°C) 2–5 kOhm Open or shorted inside the sensor
Crankshaft position sensor (CPS) 500–700 Ohm Winding damage or contact corrosion
Ignition coil (primary winding) 0.5–2 Ohm Interturn short circuit or open circuit
Lambda probe (heater) 2–10 ohms Heating element burnt out

Example of ignition coil diagnostics:

  • πŸ”§ Disconnect the coil connector.
  • πŸ” Measure the resistance between the terminals 1 and 3 (primary winding). Norm: 0.5–2 Ohm.
  • πŸ”₯ Measure the resistance between the central terminal and one of the side terminals (secondary winding). Norm: 5–15 kOhm.
  • πŸš— If the readings are outside the limits, the coil is faulty.

Common mistakes and how to avoid them

Even experienced motorists sometimes make mistakes when working with Rexant 16-0102, which leads to inaccurate readings or damage to the device. Let's look at the most common ones:

  • ⚑ Voltage measurement in current mode. If the switch is on DCA, and you are trying to measure the voltage on the battery, the device may burn out. Always check the position of the switch!
  • πŸ”Œ Ignoring polarity. When measuring DC voltage (DCV) the red probe should be on +, black - on βˆ’. If you mix it up, the sign will appear on the display βˆ’, but the device itself will not be damaged.
  • πŸ”‹ Checking current without load. Never connect the multimeter in DCA directly to the battery terminals - this is a short circuit! Only measure current through a load (such as a lamp or starter).
  • πŸ“Š Failure to take into account the internal resistance of the probes. When measuring small resistances (such as windings), first short-circuit the probes and note the readings (usually 0.1–0.3 Ohm), then subtract this value from the total.

How to extend the life of a multimeter:

  • πŸ”‹ Always turn off the device after use (switch in OFF).
  • πŸ”Œ Store the probes rolled up to avoid wire kinks.
  • πŸ’§ Do not use the device in the rain or in high humidity conditions.
  • πŸ”§ Periodically clean the probe contacts with alcohol or sandpaper.
What to do if the multimeter stops turning on?

Check the following points:

1. Battery: replace it with a new one, even if the old one β€œseems to be working.”

2. Fuses: Open the back cover and inspect them for breaks.

3. Contacts: Oxidation on the board or connectors can block power.

4. Switch: sometimes it breaks mechanically - try gently twisting it in different directions.

If all else fails, the device requires repair.

FAQ: answers to frequently asked questions

Can Rexant 16-0102 be used to test high voltage wires?

Yes, but with caution. To do this:

  1. Set the switch to mode Ξ© (resistance).
  2. Connect the probes to the ends of the high-voltage wire.
  3. Normal resistance: 3–10 kOhm (depends on the length of the wire). If the readings are higher 15 kOhm or lower 1 kOhm - the wire is faulty.

Attention: Do not measure resistance with the ignition on - it is dangerous!

Why does the device show inaccurate battery voltage values?

Possible reasons:

  • πŸ”‹ Low battery in the multimeter itself (replace it).
  • πŸ”Œ Poor contact of probes with terminals (clean contacts).
  • πŸ“Š Induced interference (for example, from a running generator). Try measuring the voltage with the engine off.
  • πŸ”§ Battery malfunction (sulfation of plates). Check the battery with a load plug.
How to check the generator diode bridge?

To do this:

  1. Disconnect all wires from the generator.
  2. Set the multimeter to mode β†’β”‚( (dialing).
  3. Connect the probes to the terminals of the diode bridge in different combinations:
    • πŸ”Ή A working diode passes current only in one direction (when calling in one direction there will be a signal, but not in the other).
    • πŸ”Έ If the diode rings in both directions, it is broken.
    • πŸ”Ή If there is no signal in either direction, there is a break.

Important: Before checking, be sure to remove the terminal from the battery!

Is it possible to measure alternating voltage (ACV) in a car?

Yes, this mode is useful for:

  • πŸ”Œ Checking the voltage at the output of the ignition coil (normal: 20–30 kV, but Rexant 16-0102 only measures up to 750 V, so a special probe is needed for high-voltage circuits).
  • πŸ’‘ Generator diagnostics (alternating voltage on the stator winding).

To measure:

  1. Connect the probes to the circuit being tested.
  2. Set the switch to 750V in the sector ACV.
  3. Take readings. Be careful - AC voltage can be dangerous!
Which multimeter is better: Rexant 16-0102 or DT-830B?

Both devices belong to the budget segment, but there are differences:

Characteristics Rexant 16-0102 DT-830B
Max. current (A) 10 10
Accuracy Β±0.5% Β±1%
Display backlight Yes (in some modifications) No
Overload protection 200 mA and 10 A fuses Only at 200 mA
Price ~1500–2000 rub. ~1000–1500 rub.

Conclusion: Rexant 16-0102 more reliable for auto diagnostics due to better protection and accuracy, but if the budget is limited, DT-830B also suitable for basic tasks.