TM-9-2350-274-BD

M109/M110/M578 VEHICLES HOWITZER, MEDIUM, SELF-PROPELLED FULL-TRACKED

TECHNICAL MANUAL; OPERATORS, ORGANIZATIONAL DIRECT SUPPORT AND GENERAL SUPPORT MAINTENANCE

JANUARY 1984

TM-9-2350-274-BD - Page 141 of 219

TM 9-2350-274-BD

ARMAMENT AND FIRE CONTROL SYSTEM

10-11. LOSS OF ACCUMULATOR PRESSURE SWITCH (M109 VEHICLES).

General Information:

The purpose of the pressure switch is to turn on the accumulator pump motor when the pressure falls

below 925 PSI or to turn off the pump motor when the pressure reaches 1225 PSI.

Limitations:

When the pressure switch is by-passed, the accumulator pump motor will run continuously causing wear

on the motor and excessive battery drain. To avoid this, the by-pass should be disconnected when the

pressure is within the proper range.

Personnel/Time Required:

●

1 soldier

●

1 minute

Materials/Tools

●

Knife or wire cutters with stripper

●

Electrical Tape

Procedural Steps:

1. Cut lines 645 and 100 that lead into the pressure switch.

2. Strip 1/4 in. to 1/2 in. from the end of each wire.

3. Twist the wires together.

4. When the pressure is between 925 PSI and 1225 PSI, the wires may be disconnected, mission

permitting

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5. Insulate all connections with electrical tape.

NOTE

Insure that the stripped end of wire does not touch the hull.

This will prevent a short circuit.

10-12. POWER LOSS TO 645 PRESSURE SWITCH LINE.

General Information:

A loss of power in the 645 line will render the pressure switch/power solenoid inoperative. Power can be

returned to these components by jumping from a dome light.

Limitations:

None

Personnel/Time required:

Change 1

10-17

Material/Tools:

●

Knife or wire cutters with stripper

●

Commo wire

●

Electrical tape