Brake Pressure Switch

TM 10-3930-634-12

(5) Again, test across the terminals. This time

there should be continuity indicated.

(6) Replace a defective brake pressure switch.

c. Removal.

WARNING

Always bleed off the pressure before

opening any part of the hydraulic brake

system by operating the brake pedal

several times with the engine not run-

ning. Failure to observe this warning

may result in serious injury to personnel.

(1) Bleed off hydraulic pressure by operating brake

pedal until all pressure has been depleted.

(2) Refer to figure 4-25 and remove the brake pres-

sure switch.

d. Cleaning and Inspection.

(1) Clean the brake pressure switch with a cloth

dampened in dry cleaning solvent P-D-680 or equal. Do

not immerse the switch in solvent or allow it to be

saturated by solvent.

(2) Inspect the switch for corrosion, cracks,

damaged threads or other damage. Replace a defective

switch.

e. Installation. Refer to figure 4-25 and install the

brake pressure switch.

NOTE: TAG AND DISCONNECT ELECTRICAL LEADS

TA0311863

Figure 4-24. Neutral start switch.

4-39. Brake Pressure Switch

a. General. The brake pressure switch is located on

the rearward structural member of the battery carrier,

adjacent to the hydraulic oil reservoir. For access,

remove the left engine side panel. From this access

point, the device is located high and to the left. An

alternate access point is through the battery carrier,

adjacent to the hydraulic oil reservoir. The signal is ac-

tivated when the accumulator hydraulic pressure drops

below 300 psi. Buzzer warning indicates that it is un-

safe to operate the vehicle.

b. Testing.

(1) Disconnect one of the two wire leads that go to

the brake pressure switch.

(2) Start and operate the engine for at least one

minute to build up the hydraulic oil pressure in the ac-

cumulator.

(3) With the wire lead disconnected, use a

multimeter to test for continuity across the two wire

lead terminals. There should be no continuity indi-

cated.

(4) Stop the engine and operate brake pedal

TA031864

several times until all hydraulic pressure in the ac-

cumulator is exhausted.

Figure 4-25. Brake pressure switch, removal and installation.

4-21