Fault Code Guide
Output Shaft Speed Sensor
Faults (PID 191)
There are four output shaft speed sensor faults cov-
ered in these procedures. One troubleshooting pro-
cedure is used to correct FMI 02, 05, and 08. A
separate procedure is used for FMI 14.
• For PID 191, FMI 02, 05, and 08 see Table 1
for procedures and pin identification.
• For PID 191, FMI 14, see Table 2 for proce-
dures.
PID 191, FMI 02, 05, 08—The Output Shaft Speed Sensor Circuit Gives Invalid Data, Is Open, or Not Broadcasting
a Signal
Failure Reason:
• The TCU has a hardware prob-
lem.
• The sensor is mounted too loose
(air gap too big).
• The sensor connectors are dam-
aged or bent.
• The wiring harness has had an
electrical failure.
• Either one of the sensors or the
TCU has failed.
07/16/2004 f544484k
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
X2
Procedure Results Action
Turn on the ignition switch and wait for
the current gear display to power up.
Fault code SID 254, FMI 12 is active. Go to Subject 309 and troubleshoot
SID 254, FMI 12.
SID 254, FMI 12 is not active. Go to the next row in the table.
Remove both output shaft speed
sensors. Reinstall and tighten the sensor
28 lbf·ft (38 N·m).
The fault clears after a test drive. No further action needed.
The fault remains active. Go to the next row in the table.
Turn off the ignition switch and wait for
the current gear display to power down.
Remove both sensor connectors and
visually inspect the pins.
The connector pins are damaged or
bent.
Repair or replace the damage.
There is no damage to either
connector.
Go to the next row in the table.
Check the upper sensor for continuity:
(1) X2 connector pin 1 to sensor pin 2;
(2) X2 connector pin 15 to sensor pin 1;
(3) X2 connector pin 14 to sensor pin 4.
There is an open circuit. Replace the transmission wiring
harness (see Subject 180).
The wiring is OK. Go to the next row in the table.
Check the lower sensor for continuity:
(1) X2 connector pin 1 to sensor pin 2;
(2) X2 connector pin 15 to sensor pin 1;
(3) X2 connector pin 9 to sensor pin 3.
There is an open circuit. Replace the transmission wiring
harness (see Subject 180).
The wiring is OK. Go to the next row in the table.
Check all four pins of each sensor
connector for voltage and for continuity
to ground.
Voltage or continuity is found. Replace the transmission wiring
harness (see Subject 180).
There is zero voltage and no continuity. Go to the next row in the table.
Freightliner AMT
3
and Mercedes-Benz Automated-Manual
Transmissions
26.03
Output Shaft Speed Sensor Faults (PID 191)
Business Class M2 Workshop Manual, Supplement 20, September 2011 317/1