TM-9-2320-280-34
TRUCK, UTILITY: M998 SERIES
TECHNICAL MANUAL; DIRECT SUPPORT AND GENERAL SUPPORT MAINTENANCE
JANUARY 1996
TM-9-2320-280-34 - Page 43 of 1258
TM 9-2320-280-34
Table 2-1. Mechanical Troubleshooting (Cont ’d)
MALFUNCTION
TEST OR INSPECTION
39.
NO ENGINE BRAKING - THIRD GEAR
Step 1.
Check front servo piston for leaking oil rings and damaged piston. Replace damaged components
(chapter 17).
Step 2.
Check front accumulator piston for leaking oil rings and damaged piston. Replace control valve (chapter 17)
if damaged.
Step 3.
Check front band for damage and proper installation. Replace front band (chapter 17) if damaged.
END OF TESTING!
40.
NO ENGINE BRAKING - SECOND GEAR
Step 1.
Check front servo piston for leaking oil rings and damaged piston. Replace damaged components
(chapter 17).
Step 2.
Check front accumulator piston for leaking oil rings and damaged piston. Replace control valve (chapter 17)
if damaged.
Step 3.
Check front band for damage and proper installation. Replace front band (chapter 17) if damaged.
END OF TESTING!
41.
NO ENGINE BRAKING-FIRST GEAR
Step 1.
Check for missing or incorrectly installed check balls. Replace missing check balls (chapter 17).
Step 2.
Check transmission case for damage at check ball locations. Replace transmission (para. 7-8) if damaged.
Step 3.
Check rear servo for leaking oil seal rings and damaged piston. Repair rear servo (para. 17-27) if damaged.
Step 4.
Check rear band apply pin for proper length. Replace pin (character 17) if length is not correct.
Step 5.
Check rear band for damage and proper installation. Replace rear band (chapter 17) if damaged.
END OF TESTING!
42.
NO DRIVE OR SLIPS IN DRIVE
Step 1.
If oil pressure in “ D “ (overdrive) at 1000 rpm is low, proceed to step 2. If oil pressure is normal, proceed to
step 4.
Step 2.
Perform steps 3, 4, and 8 of malfunction 31.
Step 3.
Check forward clutch for damage and burned clutch plates. Repair forward clutch (para 17-22) if damaged.
Step 4.
Check roller clutch for damage and proper installation. Replace roller
clutch (para. 17-24) if damaged.
END OF TESTING!
43.
NO REVERSE OR SUPS IN REVERSE
Step 1.
If oil pressure in " D " (overdrive) at 1000 rpm is low, proceed to step 2. If oil pressure is normal, proceed to
step 4.
Step 2.
Perform step 4 and steps 6 through 9 of malfunction 31.
Step 3.
Check control valve spacer plate for obstructions and misalined gasket. Clean or replace spacer plate
(chapter 17) if damaged.
Step 4.
Check control valve for damaged or leaky passages and stuck valves or incorrect as
sembly. Replace control
valve (chapter 17) if damaged.
Step 5.
Check rear servo and accumulator piston for damaged oil seal rings, pistons, and band apply pin. Check for
correct length of ban apply pin. Repair rear servo and accumulator (para. 17-27) if damaged.
Step 6.
Check center support and oil seal rings for damage and wear. Repair center support (para. 17-20) if
damaged or worn.
Step 7.
Check direct clutch for damage and burned clutch plates. Repair direct clutch (para. 17-21) if damaged.
Step 8.
Check rear band for damage and proper installation. Replace band (chapter 17) if damaged.
Step 9.
Check forward clutch for damage and binding (will not release). Repair forward clutch (para. 17-22) if
damaged.
END OF TESTING!
2-17
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