K82320750

Solution K82320750
Tuesday, February 6, 2018 9:00:23 PM CET
Solution
Title (customer effect)
Automated Manual Transmission ( AMT - F ) ( I-Shift, mDRIVE ) Clutch Valve Unit (
CVU ) Makes Intermittent Buzzing Noise With The Key On And Engine Off
Cause
The CVU on the AMT - F Transmission may make an intermittent buzzing noise with
the key on and the engine off.
Solution
Overview
The buzzing noise observed with key on engine off occurs due to low air pressure to the
Transmission Electronic Control Unit ( TECU ). There may be concerns that the CVU
will pulse intermittently as heard here. When the key is turned on and the air pressure to
the AMT-F Transmission is low, the TECU sees the low pressure and tries to move the
clutch to determine if there is truly air pressure. The symptom continues until the unit is
aired up.
Resolution
The latest TECU software update available eliminates the clutch activation function in
these conditions and the noise associated with it. If the TECU software needs to be
updated due to other issues, the symptom should no longer be present afterward. Howeve
r, since this is not considered a failure, the software should not be updated solely to
eliminate the noise.
Solution visibility
Dealer distribution
Support Area
Americas , CBR
Function(s)/component(s) affected
Function affected
Documentation , AMT , transmission , engagement , CV electronic control unit , 3 1
0 TECU , MID 130 – TECU
Function Group
Function Group
132 key; shaft , 387 warning/information analysis and display; embedded diagnostic
software , 413 clutch control , 431 gearbox, manual , 56 compressed air brake
Customer effect
Main customer effect
noise , diagnostics/methodology
Noise
hissing noise
Fluid problem
leak
Fluid implicated
air
Fluid pressure
low pressure , normal pressure , zero pressure
Conditions
Vehicle operating mode
when stationary , engagement
Frequency of occurrence of
problem
Location of problem
always
underneath cab
Administration
Author
UT9268H
Last modified by
RU4469V
Creation date
12-05-2017 19:05
Date of last update
12-01-2018 15:01
Review date
01-05-2018 00:05
Status
Published
NA_Reviewer
ut9268h
NA_Author_Group
GTT
NA_MACK_Vehicle_Range
NA_MACK_Vehicle_Ran
ge
CHU , CXU , GU , M746 , M748 , Granite , TD
NA_VOLVO_Vehicle_Range
NA_VOLVO_Vehicle_Ra
nge
VNX , VNL , VNM , VHD , VAH
Engine family
Engine family
11L Engine , 13L Engine , MP7 , MP8
Emission Standard
Emission Standard
2018 , OBD2017 , US17 GHG