TM 9-2320-361-20 2-20. STE/lCE DESCRIPTION AND OPERATION (Contd) c. Vehicle Test Meter. (1) General. The VTM provides a method for technician to test vehicle electrical and mechanical components. Readings are either pass/fail indications or digital displays in units familiar to technician (psi, rpm, volts, ohms, amps, etc.). The VTM interfaces with vehicle directly with a transducer(s) from Tranducer Kit (TK). Additional tests can also be done that involve manually probing and/or connecting transducers to appropriate test points. Operating power for VTM is drawn from vehicle batteries or some equivalent power source. Power is routed to VTM through cable clamps connected to battery. The STE/ICE general purpose testing capabilities that may be applied to vehicle are: 0-1000 psig pressure, 0-45 volts DC, and 0-40k ohms resistance. The following control functions can be performed in conjunction with special tests: interleave (displays rpm with next test), display maximum value, display minimum value, and display peak-to-peak value. (2) Controls and Indicators. The controls and readout display on VTM are illustrated. The following paragraphs describe how the controls are used, and how displays function. (a) Power Switch (PUSH ON/PULL OFF). The power switch controls DC power to VTM. The VTM can operate from either a 12-volt or 24-volt battery system. When power switch is pushed in (PUSH ON), VTM power is on. To shut VTM off, pull out power switch (PULL OFF). The power switch contains a 4-amp circuit breaker. If a fault occurs and VTM uses more power than it should, power switch will pop out automatically. Check your hookup carefully and try again before returning VTM to support maintenance. (b) TEST SELECT Switches. The TEST SELECT switches are used to select actual test to be performed. There are ten positions on each switch, numbered 0 through 9. The number dialed into these switches is read by VTM when you press TEST button. Changing TEST SELECT switch positions has no effect until TEST button is pushed on. (c) TEST Button. Depressing and releasing TEST button causes test measurement to begin. Observe measured value on readout display. The reading will be in units normally used for a particular vehicle measurement. These units are listed on the flip cards. The TEST button must be pressed and immediately released. Depressing and holding TEST button down initiates an offset test. Offset tests are described in TM 9-4910-571-12&P. (d) Readout Display. The readout display will show different types of readouts during testing up to a maximum of 4 characters (for example .8.8.8.8). Types of readouts are described in detail in paragraph (3) and are summarized as follows: 1. Status Readout. This type of readout keeps technician informed of what is happening such as power applied, failed test, etc. 2. Numerical Readout. This type of readout is the measured value in units of the measurement being made. If you are measuring 0-45 volts DC, the number 24 on display indicates 24 volts. 3. Error Readout. This type of readout indicates that wrong test number was selected, transducer is not connected, or VTM is faulty. (e) Flip Cards. The flip cards list the 2-digit test number system for selecting various tests. The cards also summarize test and operating instructions contained herein. (f) Transducer Cable Connector J4. Connectors J2 and J3 connect VTM to any transducer in transducer kit. Operating power is supplied to transducer, and signals from transducers ar supplied to VTM through the cable. Connectors J2 and J3 are identical and can be interchanged with each other or used in combination. (g) Test Probe Cable Connector J4. Connector J4 connects test leads to VTM when doing manual voltage and resistance tests. 2-150