TM-9-2320-279-20-1

M977 SERIES, 8x8 HEAVY EXPANDED MOBILITY TACTICAL TRUCKS (HEMTT)

TECHNICAL MANUAL; MAINTENANCE INSTRUCTIONS; ORGANIZATIONAL MAINTENANCE, VOLUME 1 OF 3

TM-9-2320-279-20-1 - Page 290 of 985

TM 9-2320-279-20-1

Troubleshooting Malfunctions (Cent)

Table 2-9. Troubleshooting (Cent)

kkdfunction

Test or Inspection

Corrective Action

MATERIAL HANDLING CRANE (M977, M985, M984E 1 ) (CONT)

1. CRANE WILL NOT OPERATE (CONT).

Step

2.

Check for defective power takeoff (PTO) operation.

Refer to ELECTRICAL SYSTEM Troubleshooting, MALFUNCTION 4, POWER

TAKEOFF (P!IO) SWITCH WILL NOT ENGAGE.

2. OUTRIGGER OPERATION SLOW OR ABNORMAL OR OUTRIGGERS WILL NOT EXTEND

OR RETRACT.

Step 1. Check that ENGINE HIGH IDLE assembly increases engine speed to 1500

t 50 rpm

(TM 9-2320-279-10).

If engine speed does not increase to 1500 + 50 rpm refer to ENGINE

Troubleshooting, MALFUNCTION 6, ENGINE HIGH IDLE DOES NOT OPERATE.

M977, M985 SHOWN

M984E1 SIMILAR

m

HIGH

PRESSURE

HYfi~~E{LIC

Step 2. Check for clogged high pressure hydraulic filter (para 19-17).

Service high pressure hydraulic filter

(para 19-17).

Step 3. Check for faulty hydraulic system operation.

Refer to HYDRAULIC SYSTEM Troubleshooting.

3. MAST RAISES OR LOWERS ABNORMALLY, SLOWLY, OR WILL NOT RAISE OR LOWER.

Step 1. Check that ENGINE HIGH IDLE assembly increases engine speed to 1500 ~ 50 rpm

(TM 9-2320-279-10).

If engine speed does not increase to 1500

t 50 rpm, refer to ENGINE

Troubleshooting, MALFUNCTION 6, ENGINE HIGH IDLE DOES NOT OPERATE.

Step 2. Check for clogged high pressure hydraulic filter (para 19-17).

Service high pressure hydraulic filter (para 19-17).

TA188051

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