Acquire new Allison DOC snapshot while
operating the equipment under same
conditions, if possible, noted in failure
records from Step 1.
Did DTC P0504 return?

Copyright © 2022 Allison Transmission, Inc. All Rights Reserved.

SIL 11-TR-22
July 25, 2022
Page 26 of 40

DTC P274C Transmission Converter Temperature Sensor
Circuit Low (SPN 3823 / FMI 4)
BULKHEAD
SOCKET

B
Q
C
D

A
P
b

R

c

S
E

T
F

M

N

Z

a

f

g

e
d

V

U

G

M
L

L

Y
X

Y
K

K

J

J

X

W

W

H

H

a

f

g

e
d

V

U

G

D

D

A

B

C

C

B

LOCK-UP
BODY

B

P

B

R
S

T
F

41

60

21

40

1

20

Q

b
c

80

E

C
D

LOCK-UP
BODY
SOCKET

A

A

A

A

61

CONVERTER TEMP
SENSOR
CONNECTOR

LOCK-UP
BODY
CONNECTOR

12-24 Ω

N

Z

END VIEW OF TCM
80-WAY CONNECTOR

K
B
C

SUMP TEMP
SENSOR
D
B
CONVERTER
TEMP SENSOR
A

131
119
158
154

B

CONVERTER TEMP
SENSOR
SOCKET

A
A

BULKHEAD
CONNECTOR
Q

31

X

19

T

58

b

54

H

75

B

TCM
HSD3

VBAT

LSD3
ANALOG RETURN
SUMP TEMP (+5V)

158
175

CONV TEMP (+5V)

ANALOG INTERFACE

BULKHEAD
CONNECTOR

6189057

Circuit Description
A converter temperature sensor monitors the fluid temperature in the torque converter. This test determines if
the converter temperature sensor signal is failed in the low error zone.
Conditions for Setting the DTC
The DTC will set when the TCM detects the resistance in the converter temperature circuit resistance is less
than 62.8Ω for longer than 10 seconds.

Copyright © 2022 Allison Transmission, Inc. All Rights Reserved.

SIL 11-TR-22
July 25, 2022
Page 27 of 40

DTC P274C Transmission Converter Temperature Sensor Circuit
Low (SPN 3823 / FMI 4) (cont'd)
Action Taken When the DTC Sets
• The TCM illuminates the CHECK TRANS light.
• The TCM assumes a default converter temperature of 0° C (32° F) ().
• DTC is stored in TCM history
Conditions for Clearing the DTC
The DTC will automatically become inactive and deactivate the Check Trans light if the circuit resistance returns
within normal operating limits for more than 10 seconds.
Use Allison DOC to clear the DTC from TCM history. The TCM automatically clears the DTC from the TCM history
if the vehicle completes 40 warm-up cycles without the DTC recurring.
Diagnostic Aids
• DTC P274C may be caused by:
– W175 shorted to ground or shorted to another wire in chassis harness.
– Broken or defective connector assemblies that cause pins to short together.
– Unlocked connectors, missing or damaged seals, missing seal plugs that allow moisture into connectors.
– Defective converter temperature sensor.
– Defective TCM.
– Transmission fluid temperature in torque converter reaching over 201°C (394°F) for 10 seconds.
– Inadequate or obstructed vehicle cooling system.
– Non-bypassed engine coolant thermostats that are not opening properly may cause an overheat
condition of the transmission fluid.
• The converter temperature sensor resistance is available on the Allison DOC Data Monitor grid. Prior to
selecting ’Connect’ in Allison DOC, check the ’Troubleshoot Specific Problem’ box under the “Connection
Options” and then check the ’Sensor, Voltage, Ohms, and Counts Data’ box. Check if converter temperature
sensor resistance is increasing, decreasing, or stationary with fluctuations in fluid temperature. Normal circuit
operation is indicated if sensor resistance decreases as fluid temperature increases, and sensor resistance
increases as fluid temperature decreases.
Tool Requirements
• Allison DOC
• J-39700 Universal Breakout Box
• J-47275 4th Generation TCM/VCM Breakout Harness
• J-47275-1 4th Generation TCM/VCM Magnetic Overlay
• J-46708 High Impedance Digital Multimeter

Copyright © 2022 Allison Transmission, Inc. All Rights Reserved.

SIL 11-TR-22
July 25, 2022
Page 28 of 40

DTC P274C Transmission Converter Temperature Sensor Circuit
Low (SPN 3823 / FMI 4) (cont'd)
DTC Troubleshooting Step Description
Each item number description in this list correlates to the identical number shown in the DTC table "Step" column
and is meant to briefly describe the "Action" column procedures for a particular step in the table. The DTC
troubleshooting step descriptions examine the following:
1. Check for active DTC.
2. Check W175 for short to ground, or short to another wire in chassis harness.
3. Check for active DTC.
4. Check TCM.
5. If DTC is still active, review Diagnostic Aids, begin troubleshooting again at Step 1.
Step

Action

1

1.
2.
3.

2

1.
2.

Value(s)

Connect Allison DOC.
Start engine and select N (Neutral).
Record snapshot using Allison DOC
showing active or inactive code(s).
4. Review failure records report from snapshot
to determine conditions when DTC occurs.
Is DTC P274C active or present in TCM history?
Turn ignition OFF.
Connect J-47275 4th Generation TCM/VCM
Breakout Harnessto J-39700 Universal
Breakout Box.
3. Disconnect OEM chassis harness 80-way
connector from TCM.
4. Connect OEM chassis harness to J-47275
4th Generation TCM/VCM Breakout
Harness.
5. Do NOT connect TCM side of J-47275 4th
Generation TCM/VCM Breakout Harness
to TCM.
6. Connect 16-way bypass on J-47275 4th
Generation TCM/VCM Breakout Harness.
7. Turn ignition OFF and using J-46708 High
Impedance Digital Multimeter, measure
resistance between terminal 75 and every
other labeled terminal shown on J-47275-1
4th Generation TCM/VCM Magnetic
Overlay, and to chassis ground.
Does resistance measure 20 kΩ or more
from J-47275-1 4th Generation TCM/VCM
Magnetic Overlay terminal 75 to all other
labeled terminal locations on J-47275-1 4th
Generation TCM/VCM Magnetic Overlay, and
to chassis ground?

20 kΩ or more

Yes

No

Go to Step 2

Troubleshoot
any other active
DTCs if present.
If no other DTCs
are active, go
to Step 5

Replace
converter
temperature
sensor. Go to
Step 3

Address issue
with W175. Go
to Step 5 after
repairs are made.

Copyright © 2022 Allison Transmission, Inc. All Rights Reserved.

SIL 11-TR-22
July 25, 2022
Page 29 of 40

DTC P274C Transmission Converter Temperature Sensor Circuit
Low (SPN 3823 / FMI 4) (cont'd)
Step
3

Action
1.

2.

Remove J-39700 Universal Breakout Box,
and all related harness adapters from
vehicle, if installed.
Install or reconnect all OEM connectors, if
needed.

Value(s)

Yes

No

Go to Step 4.

Go to Step 5.

NOTE: TCM 80-way connector bolt must be
tightened to 2.0-3.2 N∙m (18-28 lb in).
3.

Acquire new Allison DOC snapshot while
operating the equipment under same
conditions, if possible, noted in failure
records from Step 1.

4

Turn ignition OFF.
Install a test TCM and tighten the bolt in
the TCM 80-way connector to 2.0-3.2 N·m
(18-28 lb in).
3. Start engine and operate equipment in the
same conditions noted from the failure
records from Step 1.
4. Using Allison DOC, check for active codes.
5. If codes are not active with test TCM
installed, then turn ignition OFF and
reinstall original TCM.
6. Restart engine, operate equipment in the
same conditions noted from the failure
records from Step 1 and check again for
active DTCs.
Is DTC P274C still active with the original TCM
and inactive with a test TCM?

Install a new
TCM. Go to
Step 5 after
repairs are made.

If DTC is active
with both test
TCM and
original TCM,
then reinstall
the original
TCM. Review
Diagnostic Aids.
Go to Step 1.

5

1.

Review
Diagnostic
Aids for this
DTC. Begin the
diagnosis again.
Go to Step 1

System OK.
Clear inactive
DTCs and return
equipment to
service.

1.
2.

2.

Remove J-39700 Universal Breakout Box,
and all related harness adapters from
vehicle, if installed.
Install or reconnect all OEM connectors, if
needed.

NOTE: TCM 80-way connector bolt must be
tightened to 2.0-3.2 N·m (18-28 lb in).
3.

Acquire new Allison DOC snapshot while
operating the equipment under same
conditions, if possible, noted in failure
records from Step 1.
Did DTC P274C return?

Copyright © 2022 Allison Transmission, Inc. All Rights Reserved.

SIL 11-TR-22
July 25, 2022
Page 30 of 40

DTC P274D Transmission Converter Temperature Sensor
Circuit High (SPN 3823 / FMI 3)
BULKHEAD
SOCKET

B
Q
C
D

A
P
b

R

c