Table 2-1. Mechanical Troubleshooting (Cont'd)
TEST OR INSPECTION
28. TRANSMISSION NOISY
Check engine accessory drive components: water pump, power steering pump,
"noise" before checking transmission.
Noise in Neutral and All Driving Ranges.
Check torque converter for loose mounting capscrews and damage. Tighten capscrews
Check flywheel for damage. Replace flywheel (TM 9-2815-237-34) if damaged.
Check oil pump for obstructed oil passages, damage, and proper assembly. Repair oil
Noise in First, Second, and Reverse.
Check gear unit thrust bearings and races for damage. Replace bearing(s) and races if
Inspect gears for damage and wear. Replace damaged or worn components (para. 17-
Inspect front internal gear ring for damage. Replace gear ring if damaged (para. 17-10).
Check engine and transmission mounts for looseness or damage. Secure or replace
END OF TESTING!
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
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