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SUBJECT:

Engine Stop-Start (ES-S) Electric Pump Release Information

MODELS AFFECTED:

4000 SeriesTM Transmissions with Engine Stop-Start Electric Pumps

Introduction:
Allison Transmission is pleased to announce the launch of its new remote mount ES-S electric pump for use
in applicable 4000 Series transmissions.
The ES-S electric pump allows the engine to shut down at idle opportunities where the pump is used to keep the
transmission pressurized and 1 (First Range) maintained. This allows transmission torque availability immediately
after engine restart.
The ES-S electric pump provides many benefits including reduced operating costs due to increased fuel economy,
quieter idling at stops, lowered emissions, reduced maintenance costs and increased resale value for both the
transmission and engine due to decreased use.

Operation
The ES-S electric pump allows the engine to shut down at idle when the following conditions are met:
• Vehicle is ready (e.g., vehicle is at a stop, in neutral or a forward range, brake pedal is depressed, no
accelerator pedal input and no interlocks/inhibits)
• System is ready (e.g., battery is capable of next start)
• Transmission is ready (e.g., hydraulic pressure is good and fluid is within temperature specification)
• Engine is ready (e.g., no after treatment regeneration in progress)
While the engine is shut down, the ES-S electric pump keeps the transmission pressurized and maintains 1 (First
Range). Once movement is desired and the brake pedal is released, the engine starts and torque is available
immediately.

ES-S Electric Pump Integration
Pump Mounting
The ES-S electric pump is designed to integrate with the 4000 Series transmission. OEMs are responsible for
ES-S pump mounting; however, Allison recommends a chassis mount. The pump features three mounting bolts.
Refer to Figure 1.

DH / SL8988EN

6202355

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Figure 1. ES-S Electric Pump Bolt Locations and Dimensions
Exact mounting requirements can be found in Allison Tech Data.
Hydraulic Connections
The ES-S electric pump features an oil inlet and an oil outlet. The oil inlet uses an SAE #10 hose and the oil outlet
uses an SAE #8 hose.
New 4000 Series Channel Plate
A new 4000 Series channel plate, 4” sump, P/N 29566620 has been released to accommodate the ES-S electric
pump. Two new oil ports have been created to connect to the ES-S electric pump inlet and outlet. Refer to Figure 2.

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Figure 2. New Channel Plate and Oil Port Locations

Special Tools
No special tools are required to service the ES-S electric pump.

New Diagnostic Codes
Three new Diagnostic Troubleshooting Codes have been introduced with the ES-S electric pump. Refer to Table 1.
DTC descriptions and troubleshooting steps can be found in the 3000 and 4000 Series Troubleshooting Manual,
TS8794EN.
Table 1. New Engine Stop-Start Electric Pump DTCs
Code

Name

U0287

Lost Communication with the Engine Stop-Start Electric Pump

P2797

Engine Stop-Start System Pressure Loss

P0C2B

Engine Stop-Start Electric Pump Fault

Dry Prime Procedure
There are situations where the ES-S electric pump head may be dry and/or clearances may not allow the pump to
pull oil through the suction tube. To assist in recovering the ES-S electric pump from this dry state, a Dry Prime
procedure was developed. The Dry Prime procedure can be found below and in SM4014EN.
The Dry Prime procedure must be completed when:
• Suction or pressure hoses are removed from the ES-S electric pump or the transmission
• ES-S electric pump is removed
• Transmission sump is drained and/or a transmission filter service event is completed
• TCM is replaced
• Software or calibration is updated

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Requirements to run the Dry Prime procedure include:
• Key ON, engine OFF
• Sump temperature is greater than 15 °C (59 °F), less than 120 °C (248 °F)
• Pump connected
• CAN, ignition and power wires connected
• Level ground
Dry Prime Procedures
1. Complete action request: “Engine Off at Stop — Reset Dry Prime”.

Figure 3. Dry Prime Action Request

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2. Click “Reset”.

Figure 4. Dry Prime Reset

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3. Dry Prime complete window pops up.

Figure 5. Dry Prime Completed Sucessfully

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4. Verify Dry Prime status in the data monitor.

Figure 6. Verify Dry Prime Status
NOTE: If the Dry Prime procedure fails to complete due to a timeout issue or an error from failing to
follow the listed requirements, address the error and complete the Dry Prime procedure again. Do this
until Dry Prime passes.

ES-S Electric Pump Installation and Removal Procedure
Removal Procedure
For transmission and/or ES-S electric pump service, the pump may need to be removed from the vehicle.
1. Ensure the engine and transmission are not operating.
2. Using a flathead screwdriver, wedge the tip between the retaining clip and the connector on the ES-S electric
pump to unlock the connector. Refer to Figure 7 and Figure 8.

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Figure 7. Flathead Screwdriver with Connector

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Figure 8. ES-S Retaining Clip Extended
3. Remove the connector from the ES-S electric pump.
4. Remove input and output hoses from the ES-S electric pump and install port plugs if available.
5. Remove the three ES-S electric pump mounting bolts (75 N•m).
NOTE: Pump will be mounted on a chassis mount designed/created by the OEM.

Installation Procedure
Once service is complete on the pump and/or transmission, install the pump using the steps below.
1. Align ES-S electric pump mount bolt holes with bolt holes on the chassis mount.
2. Install the three mounting bolts in the 3 bolt holes and torque to 75 N•m.
3. If plugs have been installed in the input and output ports on the ES-S electric pump, remove the plugs.
4. Install the input hose connecting the IN port on the ES-S electric pump to the suction port (.875”-14 UNF-2B,
SAE-10 port) on the channel plate.
5. Install the output hose connecting the OUT port on the ES-S electric pump to the main pressure port
(7/16”-20 UNF-2B, SAE-04 port) on the channel plate.
6. Install the electrical connector onto the ES-S electric pump.
7. Pop the retaining clip back into the locked position on the connector to ensure proper fit and connection.

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8. Pull on the ES-S electric pump and electrical connector to ensure proper installation.
9. Complete the dry prime procedure listed in SM4014EN.

ES-S Service Kits
ES-S Spin-On Suction Filter and Filter O-Ring Service Kit
The ES-S electric pump suction filter and filter cap are made serviceable by P/N 29564210. This service part
includes the filter cartridge, filter cartridge O-ring, filter cap and filter cap O-ring. Refer to Figure 9 and Figure 10
for the complete assembly and exploded assembly. The two O-rings can be purchased separately from the filter
and filter cap in Service Kit P/N 29568877.
The ES-S electric pump filter should last the lifetime of the transmission under normal wear and operation.
During transmission service, if extreme wear and debris is found, the ES-S pump filter/filter cap assembly must
be changed. Refer to the steps below and/or the steps outlined in the service manual for proper ES-S electric
pump filter/filter cap assembly.
The ES-S electric pump filter/filter cap assembly can be serviced while the pump is still mounted on the chassis
and the input and output hoses are installed. If the ES-S electric pump application does not allow proper working
room to service the filter assembly while on the vehicle, refer to the ES-S electric pump removal process for proper
removal of the ES-S electric pump. The filter cover may be removed with a 34 mm hex socket. The filter cartridge is
press fit into the filter cap and can be removed and replaced.
Table 2. ES-S Spin-On Suction Filter and Filter O-Ring Service Kit
Qty

P/N

Figure

ES-S Spin-On Suction Filter

1

29564210

Figure 9

Filter O-ring Service Kit

1

29568877

Figure 10

Filter O-ring

1

29568875

1

Filter Cover O-ring

1

29568876

3

Part Name (indented indicates content)

Figure 9. ES-S Filter and Filter Cap Assembly
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Figure 10. ES-S Filter and Filter Cap Exploded Assembly
ES-S Check Valve Service Kit with Instruction Sheet #371
The ES-S electric pump utilizes a check ball and valve in the fluid outlet port. This check ball prevents backflow
from the main transmission pump into the ES-S electric pump. It is serviceable using Check Valve Service Kit,
P/N 29569366. Refer to Instruction Sheet #371 for service procedures.
The retaining ring, P/N 29568885, may be purchased separately if service is completed on the check valve and
the check valve components are deemed reusable. The retaining ring should be replaced each time the check
valve is removed and inspected.
Table 3. ES-S Check Valve Kit
Qty

P/N

Figure

1

29569366

Figure 11

Steel Ball

1

29568881

1

Return Spring

1

29568882

2

Carrier

1

29568883

3

Instruction Sheet #371

1

29568884

-

1

29568885

4

Part Name (indented indicates content)
Check Valve Service Kit with Instruction Sheet

Retaining Ring

(1)

(1) Retaining Ring is purchasable outside of the Check Valve Service Kit.

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Figure 11. ES-S Electric Pump Check Valve Exploded Assembly

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