Solution K44597912
Thursday, July 5, 2018 3:30:17 PM CEST

Volvo Models
Volvo Model

VNR , VNX , VNL , VNM , VHD , VAH

Engine family
Engine family

11L Engine , 13L Engine

Emission Standard
Emission Standard

2018 , OBD2017 , US17 GHG

** SOLUTION **
Title

Volvo Chassis - Automated Manual Transmission Model F (AMT-F, I-Shift) Power
Take-off (PTO) Does Not Engage Or Grinds Intermittently During Engagement Or
During Operation; Symptoms Present For PTO That Was Previously Working Properly US17+OBD16 And Newer Emissions, Common Model Years 2018 And Newer

Cause

A gearbox-mounted PTO on an AMT-F may initially engage properly, but almost
immediately begin to grind. The issue covered in this Solution will appear in a vehicle
that has a PTO that has been installed and in use for a significant period of time.
Gearbox-mounted PTOs for the AMT-F are controlled by the Vehicle Electronic Control
Unit (VECU) and/or the Body Builder Module (BBM). The VECU and BBM are not
able to diagnose electrical shorts or open circuits of these components. If a PTO-related
circuit is broken after the PTO is initially engaged, the solenoid will disengage the air
from the PTO and then re-engage when the circuit is reconnected. The disengagement
and re-engagement of the PTO mid-operation will cause it to grind.

Solution

IMPORTANT: Vehicles potentially affected by the issue described in this Solution
will have a gearbox-mounted PTO that has been installed and in use for a significant
amount of time. Older AMT-F equipped chassis that are upgraded to have a PTO
mounted on the gearbox in the aftermarket may encounter grinding from the PTO when
it is engaged. In this case, grinding will likely be observed from the time of installation.

For applicable vehicles that exhibit the conditions described in the note above
ONLY:
1. Run Accessory Kit 85151972.
2. Program the VECU.
3. Verify that the issue is corrected.

I. Symptoms commonly encountered during PTO operation with
this issue:
- Intermittently will not engage

- Grinds on engagement intermittently
- Drops out during operation
- Grinds during operation intermittently

II. If any of the above symptoms are encountered, the items below
should be checked:
A. The wiring harness and connector at the PTO Solenoid.
1. Broken, rubbed, or frayed wires.
- Special attention should be paid where the wires enter the connector seal.
2. Pins backed out of the connector/ Poor pin tension.
3. Corrosion of the pins or wiring at the connector.
B. The complete circuit from the PTO solenoid to the VECU.
1. A thorough shake test should be performed.
2. Wire should be verified as able to carry a load if continuity is
confirmed, resistance is verified to be within spec and a wiggle test of the harness
does not reveal a break.

III. Select the appropriate repair based on findings:
A. If a broken wire is found at the connector:
1. Verify that the PTO bracket currently installed is Part Number 23220187.
a. If the bracket is not the updated part:
- Update the bracket and replace the wiring harness
b. If the bracket is current:
- Repair or replace the connector or harness as necessary.
B. If an issue is found in the wiring harness that is affecting the rest of the circuit:
1. Repair or replace components as required.

IV. Inspect the PTO following repairs
A. The PTO should be removed and checked after the root cause is found and
repaired to confirm that there is no excessive damage that requires component
replacement.

NA_Sister solutions

K45382152

Solution visibility

Dealer distribution

Function(s)/component(s) affected
Function affected

automatic transmission , engagement , PTO , MID 144 – VECU

Function Group
Function Group

301 software documents, complete vehicle , 3711 Cable Harness, Complete , 481
power-take off (gearbox) , 483 control power take-off

Customer effect
Main customer effect

noise , efficiency/abnormal behavior , stop/start

Noise

grinding

Conditions
Vehicle operating mode
Frequency of occurrence of
problem
Location of problem

when activating , when stationary , engagement , with a PTO
random
underneath cab

Administration
Author

UT9268H

Dealer ID

UT9268H

Last modified by

RU4469V

Creation date

22-06-2018 17:06

Date of last update

26-06-2018 21:06

Review date

22-06-2019 00:06

Status

Published

NA_Reviewer

ut9268h

NA_Author_Group

GTT