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Solenoid tester for automatic transmissions

HT Sol 25 Test Machine

The HT-SOL is the most advanced generation of automatic solenoid testing machines to date. The innovations incorporated when engineering the HT-SOL 25 allow us to offer several unique advantages to the end customer, among these are:

  • An extensive library of benchmark results for most types of solenoids in the industry.

  • The ability to create custom benchmark results for later comparison.

  • Complete electrical and hydraulic solenoid testing.

  • Manual, semi-automatic and automatic (with the option of cyclical repetition) modes of testing.

  • The ability to set and modify the desired frequency and duration of the operating voltage of a solenoid.

  • High accuracy measurements of current and pressure values when testing solenoids.


These features make the HT-SOL the solenoid testing equipment the industry standard. This gives our customers the advantage of a significant increase in speed and quality of solenoid testing. The intuitive and easy-to-learn user interface has flexible settings, allowing the users to customize it according to their requirements and preferences. The user can easily change the number and type of displayed parameters including colors and labels of graphs of currents and pressures, limits, and tolerances of measured parameters.

New features of Gen 4 Solenoid tester

  • Increased pump performance

  • Max test pressure increased to 360 PSI (25 bar)

  • Larger capacity easy-to-replace filter with better performance characteristics

  • Added tank drain port (for fluid change and flushing of the tank)

  • Larger heating element (Increased to 1.5 kW)

  • An additional temperature measurement has been added to the solenoid supply. Temperature of ATF is not only measured in tank, but it also where the ATF is entering the solenoid adapter block with the solenoid under test.

  • Two Emergency switches are standard on the machine. One switches off the pump and the heating element when the ATF falls below the low level, the second is an easily accessible operator-controlled Emergency Stop button.

  • The solenoid control system has the ability to start solenoid control before starting the hydraulic pump.

  • Dimensions of the machine have been increased (+4 inches in width, +2 inches in depth) for easier access and solenoid adapter replacement.

  • The machine cover panels have been improved for better access for maintenance and cleaning.

  • Interior solenoid testing area has been increased.

  • The machine has been designed to keep ATF from forming puddles in the test area.

  • A secondary heating system has been included to control the temperature of the solenoid adapter block and solenoid under test (by flooding with heated ATF at the required test temperature)

  • A dedicated shelf for the keyboard and mouse has been added to keep it off the work bench surface.

Solenoid Testing Modes

Electric test of the solenoid

The electrical continuity (open or short circuit) and resistance of the solenoid is tested by observing the values of the current consumed by it (PASS/FAIL check)

Manual mode

The solenoid is tested by manually varying the operating voltage duty cycle (0-100%) and the inlet pressure, while monitoring the current, pressure, and temperature.

Automatic mode (Script)

The solenoid switches automatically according to a user-defined test script. During the script, the average voltage (controlled by duty cycle), the rate at which the voltage increases or decreases with time, as well as duration of any static voltage are sequenced automatically. The user can choose a prewritten sequence (script) from the extensive library or create their own.

Automatic mode 1

Depending on the user settings, this mode partially or completely repeats the specified script(script) in a cyclic mode. It allows repetition indefinitely as all parameters are switched automatically. The mode is stopped by the operator. It is used for long-term solenoid testing. In this mode, it is possible to display current and pressure parameters of the solenoid in real time with overlay of the reference result from the library. Any test results (for example, “before” and “after” solenoid repair) can be used as a reference.

Automatic mode 2

This mode is similar to the mode 1. It is used when two independent parts have to be “looped” in time in the test script. For the first half Automatic mode 1 is used, for the second half – Automatic mode 2 is used. In this mode, it is possible to display the current and pressure parameters of the solenoid in real time with the overlay of the reference result from the library.

Real-time mode

It is available in all automatic test modes. Live displays of the values of the current and pressure are shown on the chart in real time.

live screenshot-2.JPG

Library of reference results

The vast experience of the Hydra-Test team collected over the years has allowed us to accumulate a large database of test results. Based on this, we have created an extensive library of reference results, which include tests for all of the common automatic transmission models available in the market today. This library allows new users with at a novice level of test experience to successfully be able to test and qualify solenoids. As for professionals, they are given a vast library good test samples and statistics for scrutiny for any unusual “non-standard” behavior of tested solenoids. This significantly reduces the rejection of “suspicious” solenoids, giving the operator confidence in the results that they achieve. The reference results provided with the purchase are also templates for users to create their own library from, making the process simple and entertaining.

High-precision electronics

Precision electronics in hydratest controller
  • For high-precision measurements of the solenoid test parameters, the Hydra-Test team employs an ADC with 12 bits of resolution, which allows current measurements with an accuracy of 0.001 Amps and pressure measurements with an accuracy of 0.10 PSI (0.005 bar).

  • The standard sampling period is 0.001 seconds (1 kHz), allowing you to track even the smallest changes in the behavior of the solenoid under test. As an option, the sampling frequency of current readings can be increased to 50 kHz.

  • The standard operating voltage frequency range of the solenoid is 100 Hz to 3 kHz. An optional expansion of up to 50 kHz is possible.

  • The standard duty cycle duration can be changed in steps of 1%, with 0.5% being optionally available.

  • An optional a hydraulic fluid temperature sensor with the measurement accuracy of 0.2 °F (0.1 ℃) can be added to the system.

transmission solenoid ultrasonic cleaner

ADD-ONS: Ultrasonic Cleaner

An additional ultrasonic cleaner can be added to your HT-SOL 25 test machine to clean solenoids before you test. Cleaning them before testing will make sure your testing process is not influenced by debris and dirt of dirty solenoid. It will also keep the fluid in your machine cleaner and decrease the frequency you need to change the fluid. 




  • 5 minutes cycle with automatic shut-off

  • 35 watt ultrasonic element

  • 40 kHz ultrasonic frequency

  • Tank size (LxWxH) inches – 6.10 x 3.75 x 2.00

  • Tank capacity – 20.3 Fluid oz.

  • Solvent based liquid 

solenoid tester adapters


Hydra-Test offers an ever-increasing line of solenoid test blocks that allow you to test each solenoid hydraulically, just like it performs in the vehicle while being able to see leaks, potential wear, or other functional issues that would be impossible otherwise. Our dedicated engineering staff is continually developing new test blocks to cover the latest transmission solenoids on the market before they get to your shop. These blocks are made from precision machined aluminum to keep them light and easy to install in the machine. High quality quick connect hose connections to the machine allow for leak free and secure connections for accurate readings.

0am test plate.png

Newest development - 0AM (DQ200)

The new 0AM valve body testing tool serves as an add-on to an existing Hydra-Test solenoid tester or VB tester running on HTC. It is driven and controlled very similarly to a standard adapter plate.


The 0AM (DQ200) tool verifies:

• Pump performance
• Pump motor degradation
• Pressure loss
• Solenoid Amperage
• External and internal leaks





Testing Multiple solenoids with the HT-SOL 25: Normally the test blocks are designed to test one solenoid at a time with dedicated test holes for each type of solenoid and a test harness designed to connect to the individual solenoid. Scripts are written to test the singe solenoid and display the result graph when complete.


If you have a need for higher volume, Hydra-Test can supply custom adapter blocks that have 5 duplicate holes and dedicated harnesses that allow you to sequentially batch test up to 5 of the same solenoids at a time. The test script will be written to test each solenoid sequentially instructing the operator to move the input/output pressure hoses from solenoid to solenoid as the test progresses. At the end the result graph for all five solenoids will be displayed. 

For very high volume or remanufacturing customers, the HT-Multi- Sol EOL Test Machine has been developed. This machine will allow the operator to test up to 16 solenoids sequentially wit a fully automated machine with the ability to program pass/fail parameters that can be set and controlled by the customers engineering department. Please see

Solenoid models that can be tested: We currently have 30+ transmission Solenoid test blocks available; these cover virtually all of the late model common solenoid types used in transmissions worldwide. New solutions can be provided within our ever-expanding list of development projects. If you have a transmission model (new or old) that we do not have a test block for, we can make it for you. Sample solenoids may be required.

Writing own solenoid test scripts: the process of writing your own test data has been simplified greatly from the previous generation machines. A basic tutorial is given in the HT-VBT Deluxe guide starting at 10:33.

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