This test counts how many accelerations events occur while the brake switch input indicates "ON". Failure is
reported when the number of events exceeds 3 acceleration while Neutral at Stop is "ON".
In some applications, this test counts how many deceleration events occur while the brake switch input indicates
“OFF” and the engine running time while in range. Failure is reported when the number of events exceeds 20
deceleration events and the engine running time exceeds a calibration.
Action Taken When the DTC Sets
• The TCM does not illuminate the CHECK TRANS light.
• The CHECK TRANS indicator is illuminated on Emergency Vehicle Series (EVS) and Specialty Series
(SPS) only.
• DTC is stored in TCM history.

Copyright © 2018 Allison Transmission, Inc. All Rights Reserved.

SIL 14-TR-18
September, 2018
Page 66 of 72

DTC P0703 Brake Switch Circuit (cont'd)
• Some feature ranges may be inhibited when a valid Service Brake Status (SBS) state is not detected by the
TCM. The range inhibit light will illuminate when range is inhibited.
Conditions for Clearing the DTC/CHECK TRANS Light
Use the Allison DOC® software to clear the DTC from the 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
This DTC may be caused by:
• Open or short in wire 103 or wire 162.
• Malfunctioning brake system control components such as:
– miswired or defective brake system wiring.
– defective brake pressure switches.
• Defective TCM.
Review applicable information in the Allison DOC® Technician's Library, , and other related Appendices.
Tool Requirements:
• Allison DOC® software
• J-39700 Universal Breakout Box
• J-47275 TCM Breakout Harness
• J-46708 Digital Multimeter
• J-47275-1 Magnetic Overlay
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 for short to ground or another wire in input wire.
3. Check for high resistance or open in input wire.
5. Recalibrate TCM with updated version of original calibration.
Install a test TCM.
NOTE: The J-39700 Universal Breakout Box, adapter harnesses, jumpers, and the J-46708 Digital
Multimeter leads add a few ohms of resistance to a circuit. Refer to for the procedure to determine
the tool resistance that is added to a test circuit.

Copyright © 2018 Allison Transmission, Inc. All Rights Reserved.

SIL 14-TR-18
September, 2018
Page 67 of 72

DTC P0703 Brake Switch Circuit (cont'd)
NOTE: The Allison Transmission warranty, or the extended coverage for parts and labor, does not cover
the repair or replacement of OEM or bodybuilder-provided components or any external wire harnesses not
provided by Allison Transmission, Inc.
Before repairing or replacing these components or circuits that caused a transmission issue, always
contact the vehicle OEM call center and/or the vehicle OEM or bodybuilder service representative to
verify the warranty coverage and proper payment arrangements, arrange an alternate sublet or repair
plan (if needed), and get troubleshooting assistance for the repair (such as vehicle schematics, DTC
trees, parts assistance, etc.).

Step

Action

1

Connect the Allison DOC® software.
Start the engine.
Record snapshot using the Allison DOC®
software showing active or inactive code(s).
4. Review the failure records report from the
snapshot to determine conditions when
DTC occurs.
Is DTC P0703 active?

2

1.
2.

Value(s)

1.
2.
3.

Turn ignition OFF.
Connect the J-47275 TCM Breakout
Harness to J-39700 Universal Breakout
Box.
3. Connect the OEM chassis harness 80-way
connected to the J-47275 TCM Breakout
Harness OEM side.
4. Leave the TCM side of the J-47275 TCM
Breakout Harness disconnected from TCM.
5. Disconnect input wire at SBS signal source
end of circuit. Leave SBS wire installed in
the OEM TCM 80-way.
6. Using the J-46708 Digital Multimeter,
measure the resistance from the terminal
for the Service Brake Status (SBS) analog
input (e.g., terminal 62 for most calibrations)
on the J-47275-1 Magnetic Overlay to all
other labeled terminals on the J-47275-1
Magnetic Overlay and to chassis ground.
Does circuit resistance measure 20 kΩ or more
to all other terminals and chassis ground?

20 kΩ or more

Yes

No

Go to Step 2

Troubleshoot
any other active
codes, if present.
If no DTCs are
active, then go
to Step 6.

Go to Step 3

Resolve OEM
input wiring
issue. Go to
Step 6

Copyright © 2018 Allison Transmission, Inc. All Rights Reserved.

SIL 14-TR-18
September, 2018
Page 68 of 72

DTC P0703 Brake Switch Circuit (cont'd)
Step

Action

Value(s)

Yes

No

Turn ignition OFF.
Remove the J-39700 Universal Breakout
Box.
3. Using the J-46708 Digital Multimeter, check
for high resistance or open circuit in W162.
Does circuit resistance measure 2 Ω or less
through W162?

2 Ω or less

Go to Step 5

Resolve OEM
input wiring
issue. Go to
Step 6

3

1.
2.

4

1.

If the service outlet is authorized to use
the TCM Reflash software, recalibrate the
original TCM with the latest calibration and
software
2. Once the TCM recalibration is complete,
use Allison DOC® to check for active DTCs.
Is DTC P0703 active after reprogramming the
TCM?

Go to Step 5

Go to Step 6

5

1.
2.

Install a new
TCM. Go to
Step 6 after
repair

If DTC is active
with both test
TCM and original
TCM, then
reinstall the
original TCM.
Resolve OEM
integration issue,
e.g., defective
brake switch,
multiplex signal
source, etc. Go
to Step 6

Begin the
diagnosis again.
Go to Step 1.

Repair complete.

3.
4.
5.

6.

Turn ignition OFF.
Install test a TCM and torque bolt in the
TCM to 2.0-3.2 N·m (18-28 lb in).
Start engine.
Using the Allison DOC® software and the
snap shot feature, check for active codes.
If codes are not active with the test TCM
installed, then turn ignition OFF and
re-install the original TCM.
Restart engine and check again for active
DTCs.

NOTE: Vehicle must be road tested in order for
this code to go active.
Is DTC active with the original TCM and inactive
with a test TCM?
6

To verify the repair:
1. Turn ignition OFF.
2. Install or reconnect all OEM and
transmission components and connectors,
if needed.
3. Use the Allison DOC® software to clear
inactive DTCs from history.
4. Acquire new Allison DOC® snapshot while
driving vehicle under same conditions, if
possible, noted in failure records.
Did DTC P0703 return?

Copyright © 2018 Allison Transmission, Inc. All Rights Reserved.

SIL 14-TR-18
September, 2018
Page 69 of 72

DTC P071A Neutral at Stop Input Failed On

Circuit Description
When Function AS: Neutral at Stop is active, the Transmission Control Module (TCM) automatically commands
transmission operation at a reduced load state similar to Neutral (N). The purpose of the function is to reduce
the load on the engine when the vehicle is stopped which improves fuel economy and also reduces heat load of
the transmission in high start/stop duty cycles. To activate Neutral at Stop, the vehicle must be in first range, at a
stop, service brakes applied, accelerator pedal approximately at 0%, and the TCM GPI terminal for Neutral at
Stop must see V+, V Ign, or V Bat. Neutral at Stop deactivates when the service brake is released. Supplemental
controls such as a door switch or a Neutral at Stop enable dash switch may be wired in series with the service
brake pressure switch; alternately, a vehicle Programmable Logic Controller (PLC) output may switch the Neutral
at Stop signal as a result of a service brake pressure switch input to the PLC. The signal used to activate Neutral at
Stop may be on W102, W123 or W143, depending upon which Input/Output (I/O) package was selected in the
TCM calibration. Neutral at Stop typically uses a switch-to-battery input (analog). Refer to the Allison DOC®
Technician's Library 5th Gen I/O Functions for Neutral at Stop wiring diagrams. This test monitors whether the
Neutral at Stop input status is in a stuck "ON" or "OFF" state.
In some applications, in addition, this test counts how many deceleration events occur while Neutral At Stop
indicates “OFF” and the engine running time while in range. Failure is when the number of event exceeds a
calibration and the engine running time exceeds a calibrated time.
Table 2. Neutral at Stop
GPI#

GPI Type

TCM Pin Number

Wire Number

Wire Color

Termination Point(s)

1

+

23

123

Green

Service Brake Pressure Switch
to V+ or PLC Output

2

+

2

102

Yellow

Service Brake Pressure Switch
to V+ or PLC Output

3

+

43

143

Blue

Service Brake Pressure Switch
to V+ or PLC Output

Action Taken When the DTC Sets
When DTC P071A is active, the following conditions occur:
Copyright © 2018 Allison Transmission, Inc. All Rights Reserved.

SIL 14-TR-18
September, 2018
Page 70 of 72

DTC P071A Neutral at Stop Input Failed On (cont'd)
• The DTC is stored in the TCM history.
• The TCM does not illuminate the CHECK TRANS light.
• TCM inhibits Neutral at Stop operation.
Conditions for Clearing the DTC/CHECK TRANS Light
The Allison DOC® software may be used to clear the DTC from the TCM history. The TCM automatically clears the
DTC from the TCM history if the vehicle completes 40 warm-up cycles without the DTC recurring.
Tool Requirements
• Allison DOC®
Diagnostic Aids
This DTC may be caused by:
• Short to power or short to another wire for the GPI circuit controlling Neutral at Stop feature; i.e., W102,
W123, or W143.
• Service brake integrations: defective switch or incorrect wiring; e.g., pressure switches are closed when
they should be open. If Neutral at Stop enable switch or door switch is integrated in series, all switches
would need to be stuck closed or wired on the wrong side of switches; e.g., normally closed side versus
normally open side.
• PLC Neutral at Stop integrations: a miswired, misprogrammed, or defective circuit from PLC controlling the
TCM GPI signal for Neutral at Stop that is maintaining circuit above 3.4 volts with service brakes released.
• Neutral at Stop enabled in TCM programming error.
• TCM ground is at different voltage potential than the ground of the OEM voltage source responsible for
switching GPI circuit controlling Neutral at Stop; e.g., PLC, vehicle ignition, body controller, etc.
• Defective TCM.
DTC Troubleshooting Test Descriptions
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 for Neutral at Stop response.
3. Check Neutral at Stop response with wire removed from OEM TCM 80-way connector.
4. Check the TCM.
5. If DTC is still active, review diagnostic aids, and applicable information in the Universal Allison DOC®
Technician's Library.
NOTE: The J-39700 Universal Breakout Box, adapter harnesses, jumpers, and the J-46708
Digital Multimeter leads add a few ohms of resistance to a circuit. Refer to BEGINNING THE
TROUBLESHOOTING PROCESS for the procedure to determine the tool resistance that is added to a
test circuit.

Copyright © 2018 Allison Transmission, Inc. All Rights Reserved.

SIL 14-TR-18
September, 2018
Page 71 of 72

DTC P071A Neutral at Stop Input Failed On (cont'd)
NOTE: The Allison Transmission warranty, or the extended coverage for parts and labor, does not cover
the repair or replacement of OEM or body builder provided components or any external wire harnesses
not provided by Allison Transmission, Inc.
Before repairing or replacing these components or circuits that caused a transmission issue, always
contact the vehicle OEM call center and/or the vehicle OEM or bodybuilder service representative to
verify the warranty coverage and proper payment arrangements, arrange an alternate sublet or repair
plan (if needed), and get troubleshooting assistance for the repair (such as vehicle schematics, DTC
trees, parts assistance, etc.).

Step

Action

Value(s)

Yes

No

1

1.
2.
3.

Connect the Allison DOC® software.
Start engine.
Record snapshot using the Allison DOC®
software showing active or inactive code(s).
4. Review failure records report from snapshot
to determine conditions when DTC occurs.
Is DTC P071A active?

Go to Step 2

Troubleshoot
any other active
DTCs, if present.
If no other DTCs
are active, go
to Step 6

2

1.
2.

Start engine.
Select D (Drive) and release the service
brake.
3. Start Data Monitor feature in Allison DOC®.
4. Check status of Neutral at Stop input
function and wire state.
Are Neutral at Stop function and wire state
OFF?

Go to Step 5

Go to Step 3

3

1.
2.

Repair condition
causing high
voltage on
Neutral at
Stop input
wire. Review
Diagnostic Aids.
Go to Step 6

Go to Step 5

4

1.

Go to Step 5

Go to Step 6

Turn ignition ON.
Remove Neutral at Stop input wire from
OEM side of TCM 80-way.
3. Repeat tasks listed in Step 2.
Are Neutral at Stop function and wire state
OFF?

If the service outlet is authorized to use
the TCM Reflash software, recalibrate the
original TCM with the latest calibration and
software
2. Once the TCM recalibration is complete,
use the Allison DOC® software to check for
active DTCs.
Is DTC P071A active after reprogramming the
TCM?

Copyright © 2018 Allison Transmission, Inc. All Rights Reserved.

SIL 14-TR-18
September, 2018
Page 72 of 72

DTC P071A Neutral at Stop Input Failed On (cont'd)
Step

Action

Value(s)

Yes

No

5

1.
2.

Turn ignition OFF.
Install the test TCM and tighten the bolt to
2.0-3.2 N⋅m (18-28 lb in).
3. Install or reconnect all OEM and
transmission components and connectors.
4. Start engine, select D (Drive) and release
service brake.
5. Using the Allison DOC® software, check for
active codes.
6. If codes are not active with test TCM
installed, then turn ignition OFF and
reinstall original TCM.
7. Repeat tasks 4 and 5.
Is DTC P071A active with the original TCM and
inactive with a test TCM?

Install a new
TCM. Go to
Step 6 after
repairs are made.

If DTC is active
with both the
test TCM and
the original TCM,
do not replace
TCM. Review
Diagnostic
Aids for this
DTC. Begin the
diagnosis again.
Go to Step 1

6

1.
2.

Begin the
diagnosis again.
Go to Step 1

Repair complete.

Turn ignition OFF.
Install or reconnect all OEM and
transmission components and connectors,
if needed.
3. Acquire new Allison DOC® snapshot while
driving vehicle under same conditions,
if possible, noted in failure records from
Step 1.
Did DTC P071A return?

Copyright © 2018 Allison Transmission, Inc. All Rights Reserved.