INTRODUCTION, TEST DESCRIPTIONS, AND GO CHAIN FLOWCHARTS

TM 9-2320-361-24-1

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FIELD TROUBLESHOOTING

2-1/2 TON, 6X6, M44A2 SERIES TRUCKS (MULTIFUEL)

SIMPLIFIED TEST EQUIPMENT FOR INTERNAL COMBUSTION

ENGINE--REPROGRAMMABLE (STE/ICE-R) GO CHAIN TROUBLESHOOTING

INTRODUCTION, TEST DESCRIPTIONS, AND GO CHAIN FLOWCHARTS

INTRODUCTION

To troubleshoot a vehicle problem, the technician uses the Vehicle Test Meter (VTM), transducers, test

leads, and vehicle test cards. The VTM performs tests based upon the numbers the technician places in

TEST SELECT switches. When the technician dials in the numbers and presses the TEST button, on the

VTM, the test is initiated.

For some tests, an offset test is required before the test can be performed. To initiate an offset test, the

technician dials in a set of assigned numbers for the required test, presses and holds in the TEST button

for several seconds.

TEST DESCRIPTIONS

Offset Test

The offset test voids characteristic differences between the VTM, test leads, and transducers and also

zeros the meters. Once the offset test is performed, the VTM automatically corrects for offsets before

displaying measured values. Displayed offset values should be compared to limits on the vehicle test card

for the test being performed. If the displayed value is not within limits that are listed on the test card

then either the transducer or cable needs to be replaced.

The offset test is performed with a test probe, cable, or transducer connected to the VTM. Care should be

taken to see that no stimulus is applied to the transducer. To perform an offset test, dial test number into

the TEST SELECT switches. Press and hold the TEST button until prompting message CAL appears on

the display. In a few seconds after release of the TEST button, a number will appear. This is a measured

offset value associated with the test probe cable or transducer and cable.

Control Tests Introduction

Control tests are used to change (or control) the way a vehicle test is displayed, or the way it is run.

There are five (5) control tests:

01 Interleave (displays RPM with next test).

04 Display peak-to-peak value for next test.

02 Display minimum value for next test.

05 Initiate full power simulation.

03 Display maximum value for next test.

Control tests 01, 02, 03, and 04 specify action to be taken by the next test only.

A subsequent test will reset the control.

Control Test 1

Interleave test (Test 01) alternately measures engine speed and a second parameter such as fuel

pressure or alternator voltage. To initiate interleave, dial 01 into TEST SELECT switches and press and

release the TEST button. The prompting message PASS will signal the technician to dial in a second test

number and again press and release TEST button.

Control Test 2

Minimum Value Test, (Test 02), displays minimum value measured during a test. To initiate a minimum

value display, dial 02 into TEST SELECT switches and press and release TEST button. The prompting

message PASS will signal the technician to dial in desired test number and again press and release

TEST button. The minimum value is displayed and updated whenever a lower minimum value is measured.

Entering 02 and test number again will reset process and a new minimum value will be displayed.

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