Fault Code Guide

IMPORTANT: Always use ServiceLink when at-
tempting to diagnose problems with the auto-
mated gear shift (AGS) transmission.
In most cases, the J1587 fault code is the starting
point for the troubleshooting procedures. See Sub-
ject 300 for a list of fault codes and the location of
troubleshooting procedures for each code.
Electrical Pre-Test Instructions
Before starting any procedures, use ServiceLink to
depressurize the AGS hydraulic system. For detailed
procedures, see Subject 160.
Use the electrical pre-test instructions given in
Table 1 as a baseline for troubleshooting when there
is no definite problem, the malfunction is erratic or
intermittent, or as an informational step to determine
the general health of the electrical system. To record
your findings, a result sheet is provided at the end of
this subject. For locations of serial numbers, see
Fig. 1 and Fig. 2.
Electrical Pre-Test
Procedure Result Action
Make sure that the selector switch on the
SmartShift lever is set to N. Turn on the
ignition switch to power up the
transmission.
NOTE: If the hydraulic pump starts up with
its characteristic humming noise, this
means the main power cables are OK (see
the steps below to check the X3
connector).
The current gear indicator does not
power up normally. No fault codes
display.
Troubleshoot the current gear
indicator. See Table 4.
The current gear indicator goes
through its normal power-up
sequence, ending by displaying "N."
Turn off the ignition switch and go to
the next row in the table.
With the ignition switch off, check the
voltage at the battery.
Voltage is less than 11 or greater
than 13 volts.
Charge or replace the battery. For
battery charging procedures, see
Section 54.12, Subject 150.
Voltage is between 11 and 13 volts. Go to the next row in the table.
Remove the X3 (electric motor 2-pin)
connector from the transmission control unit
(TCU). Check the electric motor power
circuit.
06/01/2004 f544485
X3
1
2
Check for voltage between pin 1 (power
circuit 232) of the X3 connector and the
battery ground terminal.
Voltage drops more than 0.2 volts
from the voltage measured at the
battery.
Repair or replace the wiring as
needed. See Section 54.06, Subject
100.
Voltage is within 0.2 volts of the
voltage measured at the battery.
Go to the next row in the table.
Freightliner AMT
3
and Mercedes-Benz Automated-Manual
Transmissions
26.03
Troubleshooting Without Fault Codes
Business Class M2 Workshop Manual, Supplement 20, September 2011 301/1