TM-9-2320-280-34 HMMWV Direct Support & General Support Maintenance Manual Download
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TM 9-2320-280-34 Table 2-1. Mechanical Troubleshooting (Cont'd) MALFUNCTION TEST OR INSPECTION 28. TRANSMISSION NOISY NOTE Check engine accessory drive components: water pump, power steering pump, alternator, and air conditioner compressor (if installed) for the source of "noise" before checking transmission. a. Noise in Neutral and All Driving Ranges. Step 1. Check torque converter for loose mounting capscrews and damage. Tighten capscrews or replace torque converter (para. 17-4) if damaged. Step 2. Check flywheel for damage. Replace flywheel (TM 9-2815-237-34) if damaged. Step 3. Check oil pump for obstructed oil passages, damage, and proper assembly. Repair oil pump (para. 17-6) if damaged. b. Noise in First, Second, and Reverse. Step 1. Check gear unit thrust bearings and races for damage. Replace bearing(s) and races if either is damaged (para. 17-10). Step 2. Inspect gears for damage and wear. Replace damaged or worn components (para. 17- 10). Step 3. Inspect front internal gear ring for damage. Replace gear ring if damaged (para. 17-10). c. Noise during Acceleration - Any Gear. Check engine and transmission mounts for looseness or damage. Secure or replace mounts (para. 3-3 or TM 9-2320-280-20). END OF TESTING! TRANSMISSION (4L80E) NOTE •The 4L80-E Transmission is an electronically controlled four speed. The Transmission Control Module (TCM), an on board computer, receives and processes input signals from sensors on the vehicle and delivers output signals to the solenoids located on the control valve assembly. These solenoids control the transmission operating pressures, upshift and downshift patterns and torque converter clutch (TCC) operation. Unit Maintenance has recorded the Trouble Codes stored in the TCM. Refer to TM 9-2320-280-20 for definitions of trouble codes. • In the event of a major transmission malfunction involving the torque converter or oil pump, replace filter, flush oil cooler and lines before replenishing fluid. • Perform the oil pressure tests (para. 1732) and record the readings for use during troubleshooting. • Perform a road test (TM 9-2320-280-20). • Perform electrical check-out at transmission electrical connector of malfunction 29. 2-12