February 25, 2013
SERVICE MEMORANDUM
NO. SM1304 (Revised July 5, 2016)
MEMO TO: All Blue Bird Dealers
SUBJECT: Gen 4 Analog DEF Level Sensor Troubleshooting
MODEL YEAR(S): 2010-2017
MODEL(S) AFFECTED: All buses with ISB10, ISC10, ISB13, and ISL13 engines, built before 01/18/2016.
If the level of Diesel Exhaust Fluid in the tank does not appear to match the level indicated on the
dash cluster, please use the following procedure to check the level sensor. Also see attached Gen
4 Tank Assembly Service Manual.
WARNING: Always follow all Federal, State, Local and Shop safety standards and use proper
safety equipment when performing these procedures. Observe all safety precautions to secure the
bus from rolling. Park bus on a level surface, apply parking brake, turn off engine and remove
key, chock wheels.
1. With the ambient temperature above 11°F (-11°C) and the ignition turned off, fill the tank
with DEF until full.
2. Do a visual check on the DEF tank to verify a full tank. Caution: Do not over fill the tank.
3. Wait 15 minutes, then start the bus and let idle for 1 minute.
4. Check DEF level on the dash cluster.
5. If the level is 90% or more the sensor is working properly.
6. If the level is less than 90%, check the voltage across the yellow and black leads of the
sensor (while still connected to the vehicle harness and engine running) and see if the
voltage is between 0.9 and 0.49 VDC. (Piercing the insulation is not recommended.
Accessing the leads through the open end/back side of the connector is preferred).
7. If the voltage is outside of this range, then replace the level sensor.
8. If the voltage is inside of this range, then the level sensor is reading correctly and you
should contact your local Cummins dealer for further assistance.

DEF Level Sensor

Yellow &
Black Wires

BLUE BIRD BODY COMPANY
P.O. Box 937 – 402 Blue Bird Blvd – Fort Valley, Georgia – (478) 825-2021

25190 Bernwood Drive
Bonita Springs, FL 34135
239-405-6100
www.shawdev.com
ISO 9001 & 14001 Registered
TB-2859 Rev-A

GEN IV TANK ASSEMBLY SERVICE MANUAL

NOTICE OF CONFIDENTIAL INFORMATION AND PROPRIETARY RIGHTS
THIS DOCUMENT MAY NOT BE DISCLOSED TO OTHERS EXCEPT BY EXPRESS WRITTEN PERMISSION OF SHAW DEVELOPMENT, LLC. THIS DOCUMENT
CONTAINS CONFIDENTIAL COMMERCIAL AND TECHNICAL DATA, CONCEPTS AND OTHER INFORMATION, ALL OF WHICH ARE PROPRIETARY AND OF
ECONOMIC VALUE TO SHAW DEVELOPMENT, LLC. THIS DOCUMENT MAY NOT BE USED FOR MANUFACTURE OR PROCESSING USES ABSENT EXPRESS
WRITTEN PERMISSION OF SHAW DEVELOPMENT, LLC. ANY USE OTHER THAN CONFIDENTIAL EVALUATION IS STRICTLY PROHIBITED WITHOUT THE PRIOR
WRITTEN CONSENT OF SHAW DEVELOPMENT, LLC. © 2014 Shaw Development, LLC. All rights reserved.

Page 2 of 61
TB-2859 Rev-A
APPROVAL SUMMARY

Written by:
Jason Valentin
Engineering Liaison
Shaw Development, LLC

NOTICE OF CONFIDENTIAL INFORMATION AND PROPRIETARY RIGHTS
THIS DOCUMENT MAY NOT BE DISCLOSED TO OTHERS EXCEPT BY EXPRESS WRITTEN PERMISSION OF SHAW DEVELOPMENT, LLC. THIS
DOCUMENT CONTAINS CONFIDENTIAL COMMERCIAL AND TECHNICAL DATA, CONCEPTS AND OTHER INFORMATION, ALL OF WHICH ARE
PROPRIETARY AND OF ECONOMIC VALUE TO SHAW DEVELOPMENT, LLC. THIS DOCUMENT MAY NOT BE USED FOR MANUFACTURE OR
PROCESSING USES ABSENT EXPRESS WRITTEN PERMISSION OF SHAW DEVELOPMENT, LLC. ANY USE OTHER THAN CONFIDENTIAL
EVALUATION IS STRICTLY PROHIBITED WITHOUT THE PRIOR WRITTEN CONSENT OF SHAW DEVELOPMENT, LLC. © 2014 Shaw Development,
LLC. All rights reserved

Page 3 of 61
TB-2859 Rev-A
INDEX OF REVISIONS
REVISION

DESCRIPTION

A

INITIAL RELEASE

APPROVED BY/ DATE
JAV
1/2/13

NOTICE OF CONFIDENTIAL INFORMATION AND PROPRIETARY RIGHTS
THIS DOCUMENT MAY NOT BE DISCLOSED TO OTHERS EXCEPT BY EXPRESS WRITTEN PERMISSION OF SHAW DEVELOPMENT, LLC. THIS
DOCUMENT CONTAINS CONFIDENTIAL COMMERCIAL AND TECHNICAL DATA, CONCEPTS AND OTHER INFORMATION, ALL OF WHICH ARE
PROPRIETARY AND OF ECONOMIC VALUE TO SHAW DEVELOPMENT, LLC. THIS DOCUMENT MAY NOT BE USED FOR MANUFACTURE OR
PROCESSING USES ABSENT EXPRESS WRITTEN PERMISSION OF SHAW DEVELOPMENT, LLC. ANY USE OTHER THAN CONFIDENTIAL
EVALUATION IS STRICTLY PROHIBITED WITHOUT THE PRIOR WRITTEN CONSENT OF SHAW DEVELOPMENT, LLC. © 2014 Shaw Development,
LLC. All rights reserved

Page 4 of 61
TB-2859 Rev-A
TABLE OF CONTENTS

1.0

INTRODUCTION TO SHAW DEF SYSTEM ...................................................... 6
1.1

1.2

2.0

GENERAL INFORMATION: .......................................................................... 7
1.1.1

SCR SYSTEM: ....................................................................................... 7

1.1.2

DIESEL EXHAUST FLUID: .................................................................... 7

SHAW DEF COMPONENTS......................................................................... 7
1.2.1

DEF MULTIFUNCTION HEAD UNIT ..................................................... 9

1.2.2

DEF CAP.............................................................................................. 12

1.2.3

TANK AND ADAPTER ASSEMBLY ..................................................... 14

1.2.4

DEF DRAIN PLUG ............................................................................... 17

OPERATION & MAINTENANCE ...................................................................... 18
2.1

2.2

2.3
3.0

CLEANING .................................................................................................. 18
2.1.1

CLEANING THE EXTERIOR OF THE TANK ASSEMBLY .................. 18

2.1.2

CLEANING THE INTERIOR OF THE TANK ASSEMBLY.................... 19

2.1.3

CLEANING THE DEF CAP .................................................................. 20

FILLING THE DEF TANK ............................................................................ 26
2.2.1

STATION OR BULK FILLING VIA PUMP AND NOZZLE..................... 26

2.2.2

BOTTLE FILLING................................................................................. 27

DRAINING THE DEF TANK ASSEMBLY.................................................... 29
REMOVAL AND INSTALLATION INSTRUCTIONS ......................................... 31

3.1

DEF TANK MOUNTING BRACKET ............................................................ 31

3.2

COOLANT HOSES ..................................................................................... 33

3.3

DEF HOSES................................................................................................ 35
NOTICE OF CONFIDENTIAL INFORMATION AND PROPRIETARY RIGHTS

THIS DOCUMENT MAY NOT BE DISCLOSED TO OTHERS EXCEPT BY EXPRESS WRITTEN PERMISSION OF SHAW DEVELOPMENT, LLC. THIS
DOCUMENT CONTAINS CONFIDENTIAL COMMERCIAL AND TECHNICAL DATA, CONCEPTS AND OTHER INFORMATION, ALL OF WHICH ARE
PROPRIETARY AND OF ECONOMIC VALUE TO SHAW DEVELOPMENT, LLC. THIS DOCUMENT MAY NOT BE USED FOR MANUFACTURE OR
PROCESSING USES ABSENT EXPRESS WRITTEN PERMISSION OF SHAW DEVELOPMENT, LLC. ANY USE OTHER THAN CONFIDENTIAL
EVALUATION IS STRICTLY PROHIBITED WITHOUT THE PRIOR WRITTEN CONSENT OF SHAW DEVELOPMENT, LLC. © 2014 Shaw Development,
LLC. All rights reserved

Page 5 of 61
TB-2859 Rev-A
3.4
MULTIFUNCTION HEAD UNIT ASSEMBLY .............................................. 37
3.5

DEF SUCTION FILTER............................................................................... 43

3.6

LEVEL SENSOR ......................................................................................... 47

4.0

5.0

TROUBLESHOOTING PROCEDURES ........................................................... 52
4.1

TEMPERATURE SENSOR ......................................................................... 52

4.2

LEVEL SENSOR ......................................................................................... 55
FREQUENTLY ASKED QUESTIONS (F.A.Q.s) .............................................. 60

NOTICE OF CONFIDENTIAL INFORMATION AND PROPRIETARY RIGHTS
THIS DOCUMENT MAY NOT BE DISCLOSED TO OTHERS EXCEPT BY EXPRESS WRITTEN PERMISSION OF SHAW DEVELOPMENT, LLC. THIS
DOCUMENT CONTAINS CONFIDENTIAL COMMERCIAL AND TECHNICAL DATA, CONCEPTS AND OTHER INFORMATION, ALL OF WHICH ARE
PROPRIETARY AND OF ECONOMIC VALUE TO SHAW DEVELOPMENT, LLC. THIS DOCUMENT MAY NOT BE USED FOR MANUFACTURE OR
PROCESSING USES ABSENT EXPRESS WRITTEN PERMISSION OF SHAW DEVELOPMENT, LLC. ANY USE OTHER THAN CONFIDENTIAL
EVALUATION IS STRICTLY PROHIBITED WITHOUT THE PRIOR WRITTEN CONSENT OF SHAW DEVELOPMENT, LLC. © 2014 Shaw Development,
LLC. All rights reserved

Page 6 of 61
TB-2859 Rev-A
1.0

INTRODUCTION TO SHAW DEF SYSTEM

This manual was created for the purpose of familiarizing users with the Shaw
DEF Tank Assembly and its components. Furthermore, this manual provides proper
maintenance and installation instructions for the DEF tank assembly. After reviewing
this document, readers should gain a clearer understanding of how the Shaw DEF
system operates, and what preventive maintenance practices can be performed to
extend the life of DEF system.
This document is categorized into four (4) main sections: Introduction to the
Shaw Development DEF System, Operations & Maintenance, Removal & Installation
Procedures, and Frequently Asked Questions (F.A.Q.s). These sections provide
instructions for installation & disassembly (with step by step image assistance),
troubleshooting, and cleaning. For quick referencing refer to the Table of Contents for
the page locations of applicable topics. If after reviewing this document, there are
unanswered question, please feel free to contact us via the following methods.

Mailing Address:

Phone: (239) 405-6100

Shaw Development, LLC
25190 Bernwood Drive
Bonita Springs, FL 34135

Web Address: www.ShawDev.com.

NOTE: [Warnings (
) & Notes (NOTE)] These adjuncts are used throughout the
entirety of the document. These points are utilized for the purpose of simplicity and to
highlight/emphasize important points to be considered. Warnings call attention to use
of materials, processes, methods, procedures, or limits which must be followed
precisely to avoid injury to persons and/or damage to the components/equipment.
Notes call attention to methods to ease the task at hand.
NOTE: All weights and measurements are in US units and their standard Metric
conversions are enclosed in parenthesis. Temperature is called out in degree
Fahrenheit, indicated by an F, with Celsius conversion, indicated by a C, following in
parentheses.

NOTICE OF CONFIDENTIAL INFORMATION AND PROPRIETARY RIGHTS
THIS DOCUMENT MAY NOT BE DISCLOSED TO OTHERS EXCEPT BY EXPRESS WRITTEN PERMISSION OF SHAW DEVELOPMENT, LLC. THIS
DOCUMENT CONTAINS CONFIDENTIAL COMMERCIAL AND TECHNICAL DATA, CONCEPTS AND OTHER INFORMATION, ALL OF WHICH ARE
PROPRIETARY AND OF ECONOMIC VALUE TO SHAW DEVELOPMENT, LLC. THIS DOCUMENT MAY NOT BE USED FOR MANUFACTURE OR
PROCESSING USES ABSENT EXPRESS WRITTEN PERMISSION OF SHAW DEVELOPMENT, LLC. ANY USE OTHER THAN CONFIDENTIAL
EVALUATION IS STRICTLY PROHIBITED WITHOUT THE PRIOR WRITTEN CONSENT OF SHAW DEVELOPMENT, LLC. © 2014 Shaw Development,
LLC. All rights reserved

Page 7 of 61
TB-2859 Rev-A
1.1

GENERAL INFORMATION:
The following subsections provide brief descriptions of the diesel exhaust fluid
system and its components.

1.1.1 SCR SYSTEM:
The Selective Catalytic Reduction (SCR) system helps to reduce the
emission levels of nitrogen oxides released from the exhaust of diesel engines.
This is accomplished when Diesel Exhaust Fluid (DEF) is injected into the engine
exhaust system of the vehicle. Once injected, the DEF will undergo a series of
reactions that converts Nitrogen Oxides (NO & NO 2 ) in the exhaust into nitrogen
(N 2 ) and water vapor. Some of the adverse effects caused by increased
atmospheric nitrogen oxides concentrations include: promotes acid rain,
hampers the growth of plants, and can form with other pollutants to create toxic
chemicals.
1.1.2 DIESEL EXHAUST FLUID:
Diesel Exhaust Fluid (DEF), also known as AdBlue or AUS32 (Aqueous
Urea Solution 32.5%), is manufactured per ISO-22241. DEF system users are
highly recommended to familiarize themselves with this ISO specification. The
list below provides a few physical properties of DEF. If further information is
required, refer to ISO-22241.
 Freezing point of DEF ≈ 12.2° F (-11° C)
 Maximum Temperature Exposure ≈ 122° F (50° C)
 Urea Concentration: ≈ 32.5%, Water Concentration ≈ 67.5%
DEF is considered a slight irritant. Avoid contact with skin, clothing, or eyes. If it
has come into contact with skin, wash the affected area thoroughly with soapy
water. If irritation persists, seek medical attention. If it has come into contact with
eyes, flush thoroughly with water and seek medical attention if irritation persists.
If DEF is ingested, do not induce vomiting, drink plenty of water, and contact a
physician if symptoms become present.
1.2

SHAW DEF COMPONENTS
The following section provides a component level breakdown and
descriptions of each component. The Shaw Development tank assembly and
components will vary from vehicle to vehicle. For detailed descriptions regarding
a specific tank assembly model, please refer to the drawing of the part.
NOTICE OF CONFIDENTIAL INFORMATION AND PROPRIETARY RIGHTS

THIS DOCUMENT MAY NOT BE DISCLOSED TO OTHERS EXCEPT BY EXPRESS WRITTEN PERMISSION OF SHAW DEVELOPMENT, LLC. THIS
DOCUMENT CONTAINS CONFIDENTIAL COMMERCIAL AND TECHNICAL DATA, CONCEPTS AND OTHER INFORMATION, ALL OF WHICH ARE
PROPRIETARY AND OF ECONOMIC VALUE TO SHAW DEVELOPMENT, LLC. THIS DOCUMENT MAY NOT BE USED FOR MANUFACTURE OR
PROCESSING USES ABSENT EXPRESS WRITTEN PERMISSION OF SHAW DEVELOPMENT, LLC. ANY USE OTHER THAN CONFIDENTIAL
EVALUATION IS STRICTLY PROHIBITED WITHOUT THE PRIOR WRITTEN CONSENT OF SHAW DEVELOPMENT, LLC. © 2014 Shaw Development,
LLC. All rights reserved

Page 8 of 61
TB-2859 Rev-A
DEF Tank Assembly Components

1

2

3

Components
4

1. Multifunction Head Unit Assembly
2. DEF Cap Assembly
3. Tank & Adapter Assembly
4. DEF Tank Drain Plug
NOTICE OF CONFIDENTIAL INFORMATION AND PROPRIETARY RIGHTS

THIS DOCUMENT MAY NOT BE DISCLOSED TO OTHERS EXCEPT BY EXPRESS WRITTEN PERMISSION OF SHAW DEVELOPMENT, LLC. THIS
DOCUMENT CONTAINS CONFIDENTIAL COMMERCIAL AND TECHNICAL DATA, CONCEPTS AND OTHER INFORMATION, ALL OF WHICH ARE
PROPRIETARY AND OF ECONOMIC VALUE TO SHAW DEVELOPMENT, LLC. THIS DOCUMENT MAY NOT BE USED FOR MANUFACTURE OR
PROCESSING USES ABSENT EXPRESS WRITTEN PERMISSION OF SHAW DEVELOPMENT, LLC. ANY USE OTHER THAN CONFIDENTIAL
EVALUATION IS STRICTLY PROHIBITED WITHOUT THE PRIOR WRITTEN CONSENT OF SHAW DEVELOPMENT, LLC. © 2014 Shaw Development,
LLC. All rights reserved

Page 9 of 61
TB-2859 Rev A
1.2.1 DEF MULTIFUNCTION HEAD UNIT
The Shaw DEF Multifunction Head Unit Assembly (MFHU) can be found
on the top surface of the tank in the DEF tank assembly. It is fixed in place by a
retaining ring and fastened down by 2 #10-32 screws. While installed in tank, the
upper portion of the MFHU can be seen. This upper portion consists of a DEF
Suction fitting, a DEF Return fitting, a Coolant Inlet fitting, a Coolant Return
fitting, the DEF Level Sensor with wire loom, the DEF Temperature Sensor with
wire loom, and a white barcode sticker on the right side of the DEF Suction
fitting.
The bottom assembly of the MFHU consists of a coolant heater tube, DEF
Suction Tube, Level Sensor Focus Tube, and a filter element with retention
screw. The diagram below identifies each component of the MFHU and provides
a description of its purpose. The Level Sensor, DEF Suction Filter, and Bore
Seal O-ring are replaceable components of the MFHU. These items are italicized
in the chart below and indicated with the symbol, , in the following figure for
emphasis. Additionally, the Level Sensor, Temperature Sensor, and DEF Suction
Filter are described in greater detail in Sections 1.2.1.1, 1.2.1.2, and 1.2.1.3
respectively. The MFHU is designed as a replaceable item. For instruction on
removing and installing the MFHU, please refer to Section 3.5.

Component

Description

1.

Level Sensor w/ Focus
Tube

Refer to Section 1.2.1.1

2.

Temperature Sensor

Refer to Section 1.2.1.2

3.

Bore Seal O-ring

Prevents leakage of DEF and intrusion of contaminant from entering the tank
assembly through the bore seal

4.

Suction Tube

The point DEF is drawn from the tank during normal vehicle operations.

5.

DEF Suction Filter

Refer to Section 1.2.1.3

6.

DEF Return Fitting

Return Point of the DEF tank assembly

7.

Coolant Inlet Fitting

Receives heated coolant

8.

Coolant Outlet Fitting

Coolant returns to the vehicle

9.

DEF Suction Fitting

Dosing point of the DEF tank assembly

10. DEF Heater Tube

Designed to enable heated engine coolant to flow within the tank assembly.
This occurs when the DEF is exposed to cold temperatures.
NOTICE OF CONFIDENTIAL INFORMATION AND PROPRIETARY RIGHTS

THIS DOCUMENT MAY NOT BE DISCLOSED TO OTHERS EXCEPT BY EXPRESS WRITTEN PERMISSION OF SHAW DEVELOPMENT, LLC. THIS DOCUMENT
CONTAINS CONFIDENTIAL COMMERCIAL AND TECHNICAL DATA, CONCEPTS AND OTHER INFORMATION, ALL OF WHICH ARE PROPRIETARY AND OF
ECONOMIC VALUE TO SHAW DEVELOPMENT, LLC. THIS DOCUMENT MAY NOT BE USED FOR MANUFACTURE OR PROCESSING USES ABSENT EXPRESS
WRITTEN PERMISSION OF SHAW DEVELOPMENT, LLC. ANY USE OTHER THAN CONFIDENTIAL EVALUATION IS STRICTLY PROHIBITED WITHOUT THE PRIOR
WRITTEN CONSENT OF SHAW DEVELOPMENT, LLC. © 2014 Shaw Development, LLC. All rights reserved.

Page 10 of 61

TB – 2859 Rev A
DEF Multifunction Head Unit

1

6
7

2

8
9

3

10