Blue iQ® Diagnostic Service Manual

DSM.0001 Ver 1.0
July 20, 2021
DSM.0001 Ver 1.0
July 20, 2021

Blue iQ® Diagnostic Service Manual
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Table of Contents
Warning Messages and Symbols Used in this Document ............................................................................................. 3
1.

Description and Operation Overview ........................................................................................................................ 4

2.

Components, Circuit Schematics, Connector End Views, and Pinouts ............................................................... 9
2.1.

Blue iQ® gauge ................................................................................................................................................ 9

2.2.

Fuel System Control Module (FSCM) ...................................................................................................... 13

2.3.

Supply solenoid valve (SSV) ..................................................................................................................... 22

2.4.

Pressure / temperature transducer ......................................................................................................... 26

2.5.

Thermistors ................................................................................................................................................... 32

2.5.1.
2.6.

Thermistor Replacement Procedure ................................................................................................... 37
Drive Away Protection (DAP) components ........................................................................................... 39

2.6.1

Fuel door switch ....................................................................................................................................... 41

2.6.2.

Fuel receptacle cap(s) ............................................................................................................................. 42

2.6.3.

Fuel receptacle kill cap(s) ...................................................................................................................... 44

2.7.

Blue iQ FMM Harness to Blue iQ Chassis Harness bulkhead connectors ................................... 48

2.9.

SAE J1939 CAN connectors ...................................................................................................................... 52

2.10.

SAE J1939 CAN Blue iQ Gauge Harness .......................................................................................... 55

2.11.

OEM Fuel Gauge Conditioning Circuit ............................................................................................... 57

2.12.

(Optional) OEM Vehicle Interface ......................................................................................................... 59

2.13. Blue iQ System Schematic .......................................................................................................................... 60
3.

Fault Code Diagnostics ............................................................................................................................................. 60
3.1.

Fault Code (FC) Lists .................................................................................................................................. 60

3.2.

Fault Code Diagnostic Procedures ......................................................................................................... 62

Glossary of Terms .............................................................................................................................................................. 63
Contact information ............................................................................................................................................................ 66
Appendix A. Blue iQ Fuel System Control Module (FSCM) Circuit Diagram

oversize

Please refer to USM.0001 Blue iQ User Manual for detailed operating instructions.

Hexagon Agility, Inc. Copyright ©2021. All Rights Reserved.

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Please contact Hexagon Agility® Customer Care and Technical Services (CCTS) for assistance.

Warning Messages and Symbols Used in this Document
WARNING indicates a hazardous situation which, if not avoided, could result in death
or serious injury.
NOTICE is used to address practices not related to physical injury, such as best
practices or tips to help an operation or procedure go smoothly and prevent equipment
damage.

Critical
Characteristic

DSM.0001 Ver 1.0
July 20, 2021

Product feature directly affects:
 Safety of vehicle users, people nearby and maintenance personnel, or
 Regulatory compliance.

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1. Description and Operation Overview
Hexagon Agility® compressed natural gas (CNG) fuel systems equipped with Blue iQ® access original equipment
manufacturer (OEM) Cummins® engine data to maximize vehicle uptime and optimize performance. Blue iQ
sensors monitor system pressure and temperature to deliver accurate temp-compensated fuel readings via a
multifunction dashboard gauge.
Blue iQ provides crucial system monitoring and operating data including real-time fuel economy, and places
multiple functions at the operator’s fingertips. Features include the following:


Engine-Linked Startup Logic protects fuel system and engine and guards against downtime in cold
conditions



Vehicle Range Monitor calculates distance with fuel on board, provides constant and accurate fuel
readings, and instant fuel economy feedback



Eco Mode enhances fuel economy and extends vehicle range



Low Fuel Derate permits safe exit from traffic at extremely low fuel levels



Over Temperature Warning alerts driver of potentially unsafe operating conditions

Although Blue iQ systems will vary with differing vehicle configurations and applications, all systems can be
summarized with the following simplified diagram, FIGURE 1–1:

3
1

1
2
3
4
5
6
7

9
8

8
9

7

Blue iQ System Components
Fuel System Control Module (FSCM)
Supply solenoid valve (SSV)
Blue iQ gauge
Pressure / temperature transducer
Thermistor 1
Thermistor 2
FMM to chassis bulkhead harness
connectors
J1939 CAN to vehicle interface
OEM fuel gauge interface

6
4
On systems with more than one fuel compartment
(dual side mount systems or combination BTC-SM
systems), Thermistor 2 is located in the secondary
fuel system enclosure.

2

5

6

Thermistor 2 is typically located in the same fuel compartment as Thermistor 1.

FIGURE 1–1. Simplified Blue iQ fuel system diagram
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With the exception of fuel systems equipped with “box” (standalone) fuel management modules (FMMs), all Blue
iQ components are housed in fuel storage compartments with integrated FMMs. FIGURE 1–2 and FIGURE 1–3
Blue iQ Fuel Storage Compartment Components
1 Fuel System Control Module (FSCM)
4 Thermistor 1
2 Supply solenoid valve (SSV) NOTE: integral with regulator
5 FMM bulkhead connector
3 Pressure / temperature transducer
6 Thermistor 2 (not visible)

3

2

On a single side mount
fuel system, Thermistor 2
is located at the front of the
fuel storage compartment
regardless of whether the
FMM is located on driver
side or passenger side.

5

5

6

1

6

Driver side (DS) FMM with rear cover panel removed

On a dual side mount fuel
system, Thermistor 2 is
located at the front of the
non-FMM fuel storage
compartment. (See FIGURE
1–3 below.)

4

Driver side (DS) FMM with access door removed
FIGURE 1–2. Gen 5 side mount (SM) Blue iQ fuel compartment component overview
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On a single side mount
fuel system, Thermistor 2
is located at the front of the
fuel storage compartment,
regardless of whether the
FMM is located on driver
side or passenger side.

6

On a dual side mount fuel
system, Thermistor 2 is
located at the front of the
non-FMM fuel storage

4

Passenger side (PS) non-FMM fuel storage compartment with front cover panel removed
FIGURE 1–3. Gen 5 SM Blue iQ fuel storage compartment

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BTC FMM Blue iQ Fuel Compartment Components
1 Fuel System Control Module (FSCM)
4 Thermistor 1
2 Supply solenoid valve (SSV)
5 FMM bulkhead connector
3 Pressure / temperature transducer
6 Thermistor 2
PS

DS (doors removed)

(doors removed)

FRONT

FRONT

6

4

1

3

2

5

Bottom panel rendered
translucent for illustrative
purposes

FIGURE 1–3. BTC with integrated FMM Blue iQ fuel compartment component overview
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Box FMM Blue iQ Fuel Compartment Components
1 Fuel System Control Module (FSCM)
3 Pressure / temperature transducer
2 Supply solenoid valve (SSV)
4 FMM bulkhead connector

1

3

4
2

Box FMM with door and cover removed
FIGURE 1–4. Typical standalone “box” FMM Blue iQ fuel compartment component overview
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2.

Components, Circuit Schematics, Connector End Views,
and Pinouts

2.1. Blue iQ® gauge
A dash mounted Blue iQ gauge provides a user-configurable interface for vital fuel system operating data and
warning messages. FIGURE 2–1
Blue iQ
gauge

FIGURE 2–2. Blue iQ gauge and sample Blue iQ gauge screens

The Blue iQ gauge also alerts operators to fuel system faults requiring service. FIGURE 2–3

System Faults

2 Faults
1 Critical
®

Agility

FIGURE 2–3. Blue iQ gauge screen indicating multiple system faults
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Please refer to USM.0001 Blue iQ User Manual for detailed Blue iQ gauge operating instructions. FIGURE 2–4

FIGURE 2–4. USM.0001 Blue iQ User Manual

The Blue iQ gauge connects to the Blue iQ FSCM using the fuel system bulkhead harness (refer to Section 2.7.)
and communicates with OEM vehicle via the SAE J1939 CAN network (refer to Section 2.10.). FIGURE 2–5 and
FIGURE 2–6

connector end view

in-dash Blue iQ gauge

FIGURE 2–5. In-dash mount Blue iQ gauge and Blue iQ gauge connector end view

Blue iQ gauge circuit pin out

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Pin

Color

Circuit

Pin

Color

Circuit

1

Red

+12V Ignition

4

Yellow

J1939 +

2

Black

Ground

5

Green

J1939 –

3

–

–

6

–

–

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connector end view

connector image

connector harness
wire view

FIGURE 2–6. Blue iQ gauge harness and wire connector end view (inset). NOTE: Partial harness circuit shown;
Blue iQ gauge harness connects to SAE J1939 circuit harness; refer to Section 2.10.

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Blue iQ gauge circuit diagram

C11
BLUE IQ
GAUGE

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2.2. Fuel System Control Module (FSCM)
The Blue iQ Fuel System Control Module (FSCM) located inside the fuel management module (FMM) monitors
and manages fuel system function. The FSCM receives multiple inputs and utilizes internal monitors to
continuously examine and direct fuel system safety and performance. FIGURE 2–7
FSCM

Sensor inputs

Internal monitors

Datalink inputs

Vehicle inputs
FIGURE 2–7. Blue iQ Fuel System Control Monitor (FSCM) inputs

Fuel system components delivering data to the Blue iQ FSCM include the following items:
1. Pressure / temperature transducer
2. Supply solenoid valve (SSV)
3. Two fuel compartment temperature sensors called “thermistors”
4. Drive Away Protection (DAP) switches
Additionally, the OEM vehicle communicates datalink inputs including engine operating status and data to the
Blue iQ FSCM via a J1939 CAN bus connection.
Vehicle inputs to the Blue iQ FSCM are as follows:
1. Ignition ON (Battery + switch)
2. Battery power (B+)
3. Battery ground (B–)
4. Crank request
5. Fuel gauge circuit closed loop feedback

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The FSCM outputs data directing fuel system components to ensure safety and performance. FIGURE 2–8
FSCM

System outputs

Datalink outputs

Vehicle outputs
FIGURE 2–8. Blue iQ Fuel System Control Monitor (FSCM) outputs

FSCM system outputs include the following:
1. Supply solenoid valve (SSV) command (ON/OFF)
2. Sensor supply voltage (Supply 5V)
3. Sensor return (Low Reference—also called “system ground”)
FSCM datalink outputs include the following:
1. Engine Common Data Interface Messages
2. System Messages to Blue iQ gauge
3. Fault Code Status and Warning Lamps
FSCM vehicle outputs include the following:
1. Fuel Level
2. Crank Confirm
3. Low Fuel Warning
4. Drive Away Protection (DAP) Lamp. NOTE: optional on some systems.
The FSCM is located within the fuel system FMM. FIGURE 2–9; FIGURE 2–10; FIGURE 2–11; FIGURE 2–12

electrical
connector

attachment
points

FIGURE 2–9. Blue iQ Fuel System Control Module (FSCM)

DSM.0001 Ver 1.0
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