Snap-On EETA308D - User Manual

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Summary

Introduction to the Low Amp Probe

Snap-on Low Amp Probe Specifications

Electrical Specifications

Details electrical parameters like current ranges, sensitivity, accuracy, and frequency response.

General Specifications

Covers physical and environmental specifications, including conductor size, cable length, and operating conditions.

Operating Instructions for Low Amp Probe

Connecting the Probe

Instructions on how to connect the probe to test equipment via its output plugs.

Switch On and Battery Status

Explains how to turn the probe on and interpret the LED indicator for battery status.

Low Amp Current Probe Zero Adjustment

Procedure for performing the auto zero adjustment to compensate for thermal shifts.

Understanding Probe Error Factors

Discusses sources of error in current probes and how to minimize them, including the earth's magnetic field.

Reading the mV Scale

Guidance on interpreting millivolt readings and converting them to current values based on the scale.

Current Measurement Applications

Details how to use the probe for common automotive current measurements.

Summary

Introduction to the Low Amp Probe

Snap-on Low Amp Probe Specifications

Electrical Specifications

Details electrical parameters like current ranges, sensitivity, accuracy, and frequency response.

General Specifications

Covers physical and environmental specifications, including conductor size, cable length, and operating conditions.

Operating Instructions for Low Amp Probe

Connecting the Probe

Instructions on how to connect the probe to test equipment via its output plugs.

Switch On and Battery Status

Explains how to turn the probe on and interpret the LED indicator for battery status.

Low Amp Current Probe Zero Adjustment

Procedure for performing the auto zero adjustment to compensate for thermal shifts.

Understanding Probe Error Factors

Discusses sources of error in current probes and how to minimize them, including the earth's magnetic field.

Reading the mV Scale

Guidance on interpreting millivolt readings and converting them to current values based on the scale.

Current Measurement Applications

Details how to use the probe for common automotive current measurements.

The Snap-on Low Amp Current Probe, model EETA308D, is a specialized diagnostic tool designed for non-intrusive measurement of AC or DC current in various automotive and industrial applications. It is engineered to work seamlessly with digital multimeters, oscilloscopes, and other compatible recording instruments, providing accurate and reliable current readings without the need to break the circuit.

Function Description

The primary function of the EETA308D Low Amp Current Probe is to measure current flow in electrical circuits. Utilizing advanced Hall Effect technology, the probe detects the magnetic field generated by current passing through a conductor and converts this into an analog voltage output. This voltage output can then be read by a connected diagnostic instrument, such as a multimeter or oscilloscope, to display the current value.

The probe is particularly useful for diagnosing issues related to ignition coils, fuel injectors, fuel pumps, relays, electric motors, and for identifying parasitic draws in vehicle electrical systems. Its non-intrusive nature means that technicians can measure current without disconnecting wires or components, which is crucial for maintaining circuit integrity and speeding up diagnostic processes.

The EETA308D offers two selectable measurement scales: 0 to 20 Amps and 0 to 60 Amps. This dual-range capability allows for precise measurements across a wide spectrum of current levels, from very low currents (as small as 10 mA with 1mA resolution) to higher currents up to 60 Amps. The probe's frequency range extends from DC to 50 kHz, making it suitable for analyzing both steady-state DC currents and rapidly changing AC currents.

The analog voltage output varies depending on the selected range. In the 0 to 20-Amp range, the probe outputs 100 mV per 1 Amp, providing a high sensitivity for low current measurements. For example, a reading of 0.8mV corresponds to 8mA, 1.8mV to 18mA, and 21.8mV to 218mA. In the 0 to 60-Amp range, the output is 10 mV per 1 Amp, which is ideal for higher current applications where less sensitivity is required. This clear conversion factor simplifies the interpretation of readings on the connected instrument.

Usage Features

The Snap-on Low Amp Current Probe is designed for ease of use and practical application in a diagnostic environment.

Ergonomic Design: The probe features jaws with a built-in hook, specifically designed to help isolate individual wires within a bundle, making it easier to clamp onto the correct conductor for measurement.
Simple Connection: To connect the probe to test equipment, users simply plug the red connector into the CH1 input and the black connector into the GND/COM input of their multimeter or oscilloscope.
On/Off and Range Selection: A single switch controls both the power and the selection between the 20A and 60A measurement ranges. When the probe is turned on, a red LED illuminates, indicating operational status.
Low Battery Indicator: The red LED also serves as a low battery warning. If the battery voltage drops too low for normal operation, the LED will flash, alerting the user that the 9-volt alkaline battery needs to be replaced.
Auto Zero Adjustment: A critical feature for accurate current measurement, especially for low currents, is the push-button auto zero function. The output zero offset voltage of Hall Effect probes can drift due to thermal changes and environmental factors. Before taking measurements, users are instructed to ensure the probe is away from any current-carrying conductor, turn it on, select the desired range, and then press the Zero button. This calibrates the probe to eliminate any residual magnetic fields or offsets, ensuring precise readings.
Minimizing Error Factor: The manual emphasizes the importance of the zero adjustment process to reduce the "error factor," which is the amount of induced error or false reading caused by external magnetic fields, including the Earth's magnetic field. To further minimize this, users are advised to zero the probe in the same direction and inclination as its intended use.
Parasitic Draw Measurement: The probe is highly effective for diagnosing parasitic draws. Users clamp the jaws around the B+ supply wire to the power distribution box or the positive/negative battery cable. If a negative reading appears, the probe jaws should be opened and clamped in the opposite direction. The manual highlights that computer-controlled vehicles require a small amount of current to maintain module memories, and technicians should consult vehicle service manuals for specific "time-out" and maximum parasitic draw information.
Fuel Pump Current Measurement: For fuel pump diagnostics, the probe is clamped around the fuel pump voltage supply circuit, either near the fuel tank or at the fuel pump relay. The manual notes that humps in the waveform represent the condition of the pump commutator and brushes, with waveform degradation indicating brush wear and potential pump speed reduction. A tech note also suggests checking current at the fuse box using an inline fuse harness if the pump is difficult to access.
Ignition Coil Current Measurement: When measuring ignition coil current, the probe is clamped around the B+ side or the control side wire of the ignition coil, ensuring not to clamp both wires. A gradual rise or ramp in the waveform indicates normal current flow. A sharp rise at the beginning of the ramp, especially in DIS-equipped vehicles where all coils should show similar current flow, may suggest shorted coil windings. Similar to fuel pumps, a tech note provides guidance on checking current at the fuse box.
Injector Current Measurement: For fuel injectors, the probe is clamped around the B+ side or the control side wire of the injector, again avoiding clamping both wires. Sequential fuel injected vehicles will show a waveform for each injector, while bank-fired injectors will show a waveform for each injector bank. A gradual rise or ramp in the waveform is expected. High current flow may indicate a shorted injector, while a missing injector peak could point to an open injector, wiring issue, or a defective PCM driver circuit. Fuse box measurement is also an option for difficult-to-access injectors.

Maintenance Features

Maintaining the EETA308D is straightforward, focusing primarily on battery replacement and general cleaning to ensure continued accuracy and longevity.

Battery Replacement: The probe operates on a single 9-volt alkaline battery (PP3/MN1604 type). The flashing red LED indicates when the battery needs to be replaced. The replacement process involves un-clamping the probe from any conductor, turning it off, disconnecting output leads, loosening a captive screw on the battery cover, lifting the cover, inserting a new 9-volt alkaline battery, and then re-tightening the cover. The manual explicitly states that using any other type of battery will invalidate the warranty.
Cleaning: For general maintenance, the case of the probe should be cleaned periodically by wiping it with a damp cloth and a mild detergent. Users are warned against using abrasive cleaners or solvents, and it is crucial not to immerse the probe in any liquids, as this could damage the internal electronics and affect its performance.

The Snap-on Low Amp Current Probe EETA308D is a robust and essential tool for automotive technicians and electricians, offering precise current measurement capabilities with user-friendly features and simple maintenance requirements. Its design prioritizes safety, accuracy, and efficiency in diagnostic tasks.

Snap-On EETA308D Specifications

General

Model	EETA308D
Category	Test Equipment
Display	LCD
Operating Temperature	32°F to 122°F (0°C to 50°C)
Storage Temperature	-4°F to 140°F (-20°C to 60°C)
Resolution	0.1 ft-lb
Units	ft-lb, in-lb, Nm
Application	Torque measurement