TM-9-2320-280-34

TRUCK, UTILITY: M998 SERIES

TECHNICAL MANUAL; DIRECT SUPPORT AND GENERAL SUPPORT MAINTENANCE

JANUARY 1996
TM-9-2320-280-34

  TM-9-2320-280-34 - Page 41 of 1258

TM 9-2320-280-34
Table 2-1. Mechanical Troubleshooting (Cont ’d)
MALFUNCTION
TEST OR INSPECTION
32.
1-2 SHIFT FIRM OR ROUGH
Step 1.
If oil pressure in “
D " (overdrive) at 1000 rpm is normal, proceed to step 2. If oil pressure is high, proceed
to step 6.
Step 2.
Check 1-2 accumulator valve train for stuck valves or incorrect assembly. Replace control valve (chapter 17)
if any damage is found.
Step 3.
Check rear accumulator piston and oil seal rings for damage. Repair rear servo (para. 17-27) if damaged.
Step 4.
Check transmission case for restricted oil passages, damage, or porosity. Remove obstructions or replace
transmission (para. 7-8) if case is damaged or porous.
Step 5.
Check for missing or incorrectly installed check balls. Replace missing check balls (chapter 17).
Step 6.
Check control valve spacer plate for obstructions and damaged or misalined gasket. Clean or replace spacer
plate (chapter 17).
Step 7.
Check oil pump for obstructed oil passages or damage. Repair oil pump (para. 17-29) if damaged.
END OF TESTING!
33.
NO 2-3 UPSHIFT OR DELAYED UPSHIFT
NOTE
If malfunction only occurs at or near full throttle, check engine timing for
proper adjustment and check exhaust system for restrictions.
Step 1.
Check control valve for a stuck 2-3 valve, and misaligned or damaged gaskets. Replace control valve
(chapter 17) if damaged.
Step 2.
Check direct clutch for damage or burned clutch plates. Repair direct clutch (para. 17-21) if damaged.
END OF TESTING!
34. 2-3 SHIFT SOFT OR SUPS
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 3.
Step 2.
Perform steps 3 through 8 of malfunction 31.
Step 3.
Perform steps 7 and 8 of malfunction 32.
Step 4.
Check front servo for broken or missing spring and leak at servo pin. Repair front servo (chapter 17) if
damaged.
WARNING
Compressed air used for cleaning purposes will not exceed 30 psi
(207 kPa). Use only with effective chip guarding and personnel protective
equipment (goggles, shield, gloves, etc.).
Step 5.
Air check direct clutch piston for proper operation. If piston exhibits excessive l
eakage, proceed to step 6. If
operation is normal, proceed to step 7.
Step 6.
Check direct clutch piston, plates, and release springs for damage or incorrect assembly. Repair
intermediate clutch (para. 17-17) if damaged.
Step 7.
Check transmission case passages for leaks. Replace transmission (para. 7-8) if case is damaged.
END OF TESTING!
35. 2-3 SHIFT FIRM OR ROUGH
Step 1.
If oil pressure in “ D “ (overdrive) at 1000 rpm is normal, proceed to step 2. If oil pressure is high, proceed
to step 5.
Step 2.
Check front accumulator for damaged piston, rings, and broken or missing spring; check valve to
accumulator feed for obstructions. Replace control valve (chapter 17) if damaged.
2-15


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