M2/M3 BFV: TROUBLESHOOTING - OD1610 - LESSON 1/TASK 2
2.
Diagnosing Malfunctions
The word "diagnosis" means the act or process of deciding the nature of a
problem through examination and analysis. When we diagnose a malfunction in
the BFV or any other piece of equipment, that is exactly what we are doing--
examining and analyzing the equipment or system to determine what is wrong
and why.
In our discussion of the general and specific troubleshooting procedures in
Task 1, we covered the major portion of the procedures for diagnosing
malfunctions. Through the use of the inspection and test procedures used in
troubleshooting, we are examining and analyzing the problem to come up with
a possible cause and to identify the corrective action necessary to rectify
the malfunction.
One of the main tools used by mechanics to diagnose malfunctions is the
simplified test equipment-M1/fighting vehicle system (STE-M1/FVS) vehicle
test meter (VTM). This piece of test equipment and some of the tests it is
capable of performing will be discussed in the paragraphs that follow.
a. STE-M1/FVS VTM. The vehicle test meter (VTM) is a tool for testing
electrical and mechanical components. Readings are in either pass/fail, or
digital displays (psi, rpm, volts, etc.).
The VTM interfaces with the
vehicle through the use of diagnostic connector assemblies (DCAs).
The VTM is connected to one of two DCAs in the vehicle: DCA 3, jack 1A1J14
which is on the vehicle power distribution box, and DCA 13, jack 1A1J15
which is also on the vehicle power distribution box. In the paragraphs that
follow, we will discuss the procedures for connecting the VTM to both of
these DCAs.
(1) Hook Up VTM to DCA 3. To hook up the VTM to DCA 3, first remove
the VTM and cable W1 from the transit case.
After the VTM and the cable
have been removed from the transit case, move the equipment out to the
vehicle. When the equipment is at the vehicle, pull the VTM circuit breaker
to the OFF position.
Before the VTM can be connected to the vehicle, be
sure the engine is stopped and that the FIRE SUPPRESSION switch is in the
MANUAL position. Now connect plug W1P1 to jack J1 on the
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