TM-9-2350-311-20-1

HOWITZER, MEDIUM, SELF-PROPELLED, 155MM; M109A2, M109A3, M109A4 AND M109A5

TECHNICAL MANUAL; UNIT MAINTENANCE MANUAL FOR HULL, POWERPLANT, DRIVE CONTROLS, TRACKS, SUSPENSION, AND ASSOCIATED COMPONENTS

AUGUST 1994

TM-9-2350-311-20-1 - Page 1191 of 1275

TM9-2350-311-20-1

1

CONDITION CURRENT PROBE

DO OFFSFT:

.

.

- Connect P1 of transducer cable W4 to J3 on the VTM.

- Connect P2 of cable W4 to current probe, TK item 11.

- Clamp current probe around positive battery cable

connected to starter. Point arrow on probe toward starter.

- Make sure current probe is closed.

.

Crank engine for several cycles with fuel shut off.

- Engage starter long enough to briefly turn engine

(approximately 1 second).

- Turn off all vehicle electrical power.

I

NOTE

I

If engine does not

crank, go to NG 20

(Figure 3, sheet 1).

Engine must not start

while performing this

step. If engine starts,

repeat step.

- Set TEST SELECT switches to 72, press and hold

TEST button until CAL message appears on display.

- Release TEST button.

- Wait for offset value to appear.

I

S

offset value within the limits of -225 to +225?

While cranking engine with bad or

discharged batteries, it is possible for

VTM to lose power and come on

again displaying ---- after cranking

stops. If this ever occurs, go to NG 21

(Figure 3, sheet 2).

Refer to TM 9-4910-571-12&P

for offset fault isolation.

MEASURE CURRENT - FIRST

PEAK:

- Press and release TEST button.

- Wait for prompting message GO

to appear on display.

When GO appears, crank

engine until-OFF or error

message is displayed

(approximately 2 seconds)

Figure 2, Sheet 8 of 20

I-14

Go to Figure 2,

sheet 9.

NOTE