September, 2018
Page 13 of 72

DTC P071A Neutral At Stop Input Failed On

Circuit Description
When Neutral at Stop is active, the 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 or, 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 is 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.
This test counts how many accelerations events occur while the Neutral at Stop input indicates "ON". Failure is
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 Neutral At Stop indicates “OFF”
and the engine running time while in range. Failure is when the number of event exceeds 20 deceleration events
and the engine running time exceeds a calibrated time.
Table 1. Neutral at Stop
GPI#

GPI Type

TCM Pin Number

Wire Number

Wire Color

Termination Point(s)

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:
• The DTC is stored in the TCM history.
Copyright © 2018 Allison Transmission, Inc. All Rights Reserved.

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

DTC P071A Neutral At Stop Input Failed On (cont'd)
• The TCM does not illuminate the CHECK TRANS light.
• TCM inhibits Neutral at Stop operation.
Conditions for Clearing the DTC/CHECK TRANS Light
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.
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., W143.
• For 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 integrated in series, all switches would
need to be stuck closed or wired on wrong side of switches, e.g., normally closed side vs normally open side.
• For 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 in 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.
Tool Requirements:
• Allison DOC® software
• J-39700 Universal Breakout Box.
• J-47275 TCM Breakout Harness.
• J-47275-1 TCM Magnetic Overlay.
• J-47278 1K2K Transmission Breakout Box Overlay
• J-46708 Digital Multimeter.
Test 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 Neutral at Stop response.
3. Check for Neutral at Stop response with wire removed from OEM TCM 80-way connector.
5. Check the TCM.
6. Install a test TCM

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

SIL 14-TR-18
September, 2018
Page 15 of 72

DTC P071A Neutral At Stop Input Failed On (cont'd)
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.

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
DOC®

Value(s)

Yes

No

1

1.
2.
3.

Connect the Allison
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 7

2

1.
2.

Go to Step 6

Go to Step 3

3

1.
2.

Repair condition
causing high
voltage on
Neutral at
Stop input
wire. Review
Diagnostic Aids.
Go to Step 7

Go to Step 6

4

NOTE: In most cases the TCM is not at fault.
Investigate thoroughly before replacing the
TCM. Refer to 4-6. TCM Diagnostic Procedure.

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

Go to Step 5

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

SIL 14-TR-18
September, 2018
Page 16 of 72

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

Action

Value(s)

Yes

No

5

1.

Go to Step 6

Go to Step 7

6

1.
2.

Turn ignition OFF.
Install the test TCM and tighten the bolt in
the TCM 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 7 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

7

1.
2.

Begin the
diagnosis again.
Go to Step 1

Repair complete.

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 recalibrating the
TCM?

Turn ignition OFF.
Install or reconnect all OEM and
transmission components and connectors,
if needed.
3. Acquire a 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.

SIL 14-TR-18
September, 2018
Page 17 of 72

DTC P0703 Brake Switch Circuit

NOTE: If chassis ground is used, omit wire 103.

Circuit Description
This test monitors whether vehicle service brake switch status is in a stuck "ON" or "OFF" state.
Service brake status is relayed to the TCM by a mechanical switch, or over the J1939 datalink indicating the
service brake has been applied. Input wire 162 is used to send a positive signal to the TCM. Wire 103 is used in
this circuit as the signal return to the TCM.
DTC P0703 is only triggered when input wire 162 is being used for the service brake status signal and when the
number of vehicle accelerations with brake switch “ON” exceeds a calibration value. This DTC may also set when
the number of vehicle decelerations to a stop with the brake switch “OFF” exceeds a calibration value. This code
will not be triggered if the Service Brake Status Input is broadcast on J1939 datalink.
This test counts how many accelerations events occur while the brake switch input indicates "ON". Failure is when
the number of events exceeds 3 acceleration while Neutral at Stop is "ON".
In some applications, in addition, 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.

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

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

DTC P0703 Brake Switch Circuit (cont'd)
• The CHECK TRANS indicator is illuminated on EVS (Emergency Vehicle Series) and SPS (Special Series)
only.
• The DTC is stored in TCM history.
• No Grade Braking Allowed.
• The Service Transmission message is displayed in the vehicle message center on the Silverado 4500HD,
5500HD, 6500 HD and the Navistar CV models.
• Auto Neutral disabled.
• Use the default assumption that the brake is off.
• Neutral At Stop is disabled (if equipped).
NOTE: When connecting the Allison DOC® software to a General Motors Silverado 4500HD, 5500HD and
6500HD models or a NAVISTAR CV model use the J-48624 Translator and the J-41788 OBD II Connector.
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, BEGINNING THE TROUBLESHOOTING
PROCESS, and other related Appendices.
Tool Requirements:
• Allison DOC® software
• J-39700 Universal Breakout Box
• J-47275 TCM Breakout Harness
• J-47275-1 TCM Magnetic Overlay
• J-47278 1K2K Transmission Breakout Box Overlay
• J-46708 Digital Multimeter

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

SIL 14-TR-18
September, 2018
Page 19 of 72

DTC P0703 Brake Switch Circuit (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. This step tests for active DTC.
2. This step tests the Service Brake Status.
3. This step tests for voltage on TCM input pin 62 when the service brakes are applied and released.
4. This step checks for open brake fuse.
5. This step tests for open condition in the OEM wire harness, wire 103 and wire 162.
6. The step tests for wire to wire shorts in the OEM wire harness.
7. This step tests for shorts to ground in the OEM wire harness.
9. Repair or replace brake pressure switch.
11. Recalibrate TCM with updated version of original calibration.
12. 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 BEGINNING THE
TROUBLESHOOTING PROCESS for the procedure to determine the tool resistance that is added to a
test circuit.

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
1

Action
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 P0703 active?

1.
2.
3.

Value(s)

Yes

No

Go to Step 2

Troubleshoot
any other active
codes, if present.
If no DTCs are
active, then go
to Step 2.

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

SIL 14-TR-18
September, 2018
Page 20 of 72

DTC P0703 Brake Switch Circuit (cont'd)
Step
2

Action
1.
2.
3.

Value(s)

Turn ignition ON, with the engine off.
Record the DTC failure record data.
Apply and release the service brake

Yes

No

Go to Step 11

Resolve OEM
input wiring
issue. Go to
Step 3

Go to Step 12

Go to Step 4

NOTE: This function may be on the J-1939
datalink, use the Allison DOC® software to
determine the source of the brake message
Does the Allison DOC® software indicate that
the brake switch is toggling off and on the input
wire 162?
Brakes applied
0.0V, Brakes
released 5.0V

3

1.
2.

4

1. Remove the brake fuse.
2. Inspect the fuse for open condition
Did you find and repair the condition?

Go to Step 13

Go to Step 5

5

1.
2.

Go to Step 8

Go to Step 6

Turn ignition OFF.
Disconnect the 80- way connector at the
TCM.
3. Install the J-39700 Universal Breakout
Harness and the J-47275 TCM Breakout
Box Adaptor between the TCM 80-way
connector and the OEM wire harness
80-way connector.
4. Turn on the ignition.
5. Measure the voltage at pin 62 on the
J-47275-1 TCM Magnetic Overlay On the
J-39700 Universal Breakout Box.
6. Apply and release service brake.
Is the voltage within specified value?

Turn ignition OFF.
Leave the 80-way connector disconnected
at the TCM.
3. Disconnect the brake pressure switch
connector.
4. Using J-39197-A Jumper Wire Kit, install a
jumper wire between wires 162 and 103 in
the brake pressure switch connector.
5. Measure for continuity between pins 62 and
3 on the J-47275-1 TCM Magnetic Overlay
on the J-39700 Universal Breakout Box.
Was continuity measured between these pins?

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

SIL 14-TR-18
September, 2018
Page 21 of 72

DTC P0703 Brake Switch Circuit (cont'd)
Step

Action

Value(s)

Yes

No

6

1.
2.

Turn ignition OFF.
Leave the 80-way connector disconnected
at the TCM.
3. Remove the jumper wire from the brake
pressure switch connector and leave
connector disconnected.
4. On the J-47275-1 TCM Magnetic Overlay
on the J-39700 Universal Breakout Box,
measure pins 62 and 3 to all other pins.
Was continuity measured between these pins?

Go to Step 8

Go to Step 7

7

1.
2.

Turn ignition OFF.
Leave the 80-way connector disconnected