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Blue iQ is used with both 12V and 24V supply solenoid valves (SSVs); use the correct table to determine proper
SSV coil operation. TABLE 2–1 and TABLE 2–2
TABLE 2–1. 12V Standalone Supply Solenoid Valve (SSV) Coil Resistance at Temperature Chart

TABLE 2–2. 24V Standalone Supply Solenoid Valve (SSV) Coil Resistance at Temperature Chart

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Supply solenoid valve (SSV) circuit diagram
Y40
SUPPLY
SOLENOID
VAVLE

C10
FUEL SYSTEM
CONTROL MODULE

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2.4. Pressure / temperature transducer

The pressure / temperature transducer allows Blue iQ to monitor high-pressure fuel entering the pressure
regulator at approximately 3600 psi (24.8 MPa) before the regulator reduces fuel pressure to from 85 psi* (0.59
MPa) to 125 psi (0.86 MPa) for use by the engine, depending upon application. TABLE 2–3
TABLE 2–3. Low Pressure Fuel Requirements by Engine Size and Pressure Regulator Type

Engine
size

LP fuel
pressure

Pressure
regulator type

9L

125 psi
(0.86 MPa)

standard

12L

87 psi
(0.60 MPa)

standard

12L

85 psi
(0.59 MPa)

Marathon –
extended range

As its name implies, the pressure/temperature transducer also monitors fuel temperature. FIGURE 2–17a
Pressure / temperature transducer
electrical
connector

port
fitting
FIGURE 2–17a. Pressure / temperature transducer

Depending upon system design, the pressure / temperature transducer may be located on a manifold or the
Manifilter [high-pressure (HP) filter]. FIGURE 2–17B

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®

ProCab BTC
1

2

3

®

ProRail Gen 5 SM

Box FMM

4
1

1

3

3
FIGURE 2–17b. Pressure transducer locations in box FMM, ProCab® BTC, ProRail® Gen 5 SM fuel systems.

1 pressure transducer
2 pressure regulator

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3 Manifilter
4 manifold

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The pressure/temperature transducer has an integral temperature sensor that is monitored by the Blue-iQ FSCM.
The output voltage of the transducer or both temperature and pressure are ratio-metric outputs in which the
output voltage scales with the voltage supplied to the transducer. If the transducer measures a pressure or
temperature that is half of the full scale, then the output would be equal to half of the supply voltage. In the case
of a 5V sensor this would be 2.5V and in the case of a 12V sensor it would be 6V. The voltage supplied to the
pressure transducer is regulated to 5V by the Blue iQ FSCM.
The transducer has a pressure range of zero psi (zero MPa) to 6000 psi (41.4 MPa) which corresponds to 0.5V
and 4.5V, respectively. TABLE 2–4
TABLE 2–4. Pressure / temperature Transducer Voltage at Pressure Chart

The pressure/temperature transducer has a temperature range from -40°F to 221°F (-40°C to 105°C) with an
output voltage of 0.5V to 4.5V, respectively. TABLE 2–5

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TABLE 2–5. Pressure/temperature Transducer Voltage at Temperature Chart

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connector end view

connector image

FIGURE 2–18. Pressure / temperature transducer circuit and connector views

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Pressure / temperature transducer circuit pin out

Pin

Color

Circuit

1

Black/White

Low Reference

2

Violet

5V Supply

3

Blue

Temperature Signal

4

Blue/White

Pressure Signal

Pressure / temperature transducer circuit diagram

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2.5. Thermistors

Two temperature sensors called “thermistors” 1 located at opposite extremes within the fuel system
compartment(s) allow the Blue iQ FSCM to calculate temperature-compensated pressure readings to deliver
accurate fuel readings and ensure fuel system safety. FIGURE 2–19a and FIGURE 2-19b
Thermistor assembly

thermistor
LHS BTC

(top door removed for clarity)

RHS BTC

(top door removed for clarity)

LHS SM

(rear door removed for clarity)

FRONT
2
FRONT

1

1
RHS SM

FRONT

(remove front panel for access

2

FIGURE 2–19a. Typical BTC and Gen 5 SM thermistor locations: (1) Thermistor 1, (2) Thermistor 2

As a rule, Thermistor 1 is located in the FMM or on the side of the system nearest the FMM. The location of
Thermistor 2 varies with fuel system configuration.
1

Cummins® INSITE™ software refers to thermistors as “Fuel Compartment Temperature Sensors.”

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system valve end

1

system
plug end

1

FIGURE 19b. Gen 3 Refuse Roof Mount (RM) Thermistor Locations

1 Thermistor 1

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2 Thermistor 2

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Functionally, the thermistors measure electrical resistance and translate it into temperature readings. TABLE 2-6
TABLE 2–6. Thermistor Resistance at Temperature Chart

Each thermistor has a 5V Signal circuit and a Low Reference circuit which are provided from the FSCM. The
signal circuit in the FSCM monitors the 5V Signal using a resistor; if there is an open circuit, the analog pin will
default to the peak 5V reading. Thermistor 1 and Thermistor 2 share the Low Reference circuit. FIGURE 2–20

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thermistor harness connector end view

thermistor connector end view

thermistor harness connector image

thermistor connector image

FIGURE 2–20. Thermistor wiring schematic and connector views

Thermistor 1 & Thermistor 2 circuit pin out

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Pin

Color

Circuit

A

Blue

5V Supply

B

Black/White

Low Reference

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Thermistor 1 & Thermistor 2 (Fuel Storage Compartment Temperature Sensor #1 & #2) Circuit Diagram

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2.5.1. Thermistor Replacement Procedure
If replacing a thermistor assembly, care must be exercised to remove it without damaging adjacent cylinders or
wiring and mounted according to system thermistor mounting requirements.
Side mount (SM) Systems
1. Drill out (6) rivet securing (1) thermistor assembly (2) loop to (3) structure. FIGURE 2-21
Use caution not to contact adjacent plumbing, or harness when drilling out rivet.

thermistor interface

5
4

rivet

HP fuel tube

1
harness

6

2
3

FIGURE 2–21. Thermistor mounting detail, Gen 5 SM systems. NOTE: Thermistor 1 shown; thermistor 2 similar.

1 thermistor assembly
2 thermistor loop

3 structure
4 Blue iQ harness connector

5 thermistor connector
6 rivet

2. Unplug (1) thermistor assembly (5) connector from Blue iQ harness at thermistor interface. FIGURE 2-21
3. Use a 6) rivet* to mount (1) thermistor assembly to (3) structure using (2) loop. FIGURE 2-21
4. Connect (1) thermistor assembly (5) connector to (4) Blue iQ chassis harness connector at thermistor
interface.
Do not allow tension on thermistor interface. FIGURE 2–21
*Please contact Hexagon Agility® CCTS to order.

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Behind the Cab (BTC), Roof Mount (RM), and Front of Body (FOB) Systems
1. Disconnect (1) thermistor assembly (5) connector from (2) Blue iQ harness connector. FIGURE 2–22
3

1

5
4
2
FIGURE 2–22. Use side cutters to remove edge clip zip ties from thermistor assembly

1 thermistor sensor (not visible; red box)
2 Blue iQ harness connector

3 edge mount zip tie
4 side cutters

5 thermistor connector

2. Use (4) side cutters to remove zip ties. FIGURE 2–22
3. Use (3) QTY: 2 edge clip zip tie, p/n 10712380, to mount each (1) thermistor assembly, placing one
edge clip on each end of thermistor assembly. FIGURE 2–23
Do not position (3) edge clip zip ties on (2) thermistor sensor. FIGURE 2–23
edge clip zip tie
3

2

5
4

1
FIGURE 2–23. Thermistor mounting details, BTC. NOTE: Other non-SM systems similar.

1 thermistor assembly
2 thermistor sensor (not visible; red box)

3 edge clip zip tie
4 thermistor connector

5 thermistor interface

Both (3) edge clips must face the same direction. FIGURE 2–23
Do not allow tension on (5) thermistor interface. FIGURE 2–23

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2.6. Drive Away Protection (DAP) components
The Blue iQ Drive Away Protection (DAP) feature prevents engine starting unless all fuel doors and fuel caps
(including auxiliary fill caps) are securely in place. The Blue iQ gauge displays a “Starter Lockout—Fill
Receptacle” message indicating a fuel door is open or a fuel receptacle cap is not installed properly. FIGURE 2–
24

FIGURE 2–24. “Starter Lockout—Fill Receptacle” Blue iQ gauge warning message

Three types of DAP are used with Blue iQ on various fuel systems (FIGURE 2–25):
1. Fuel door switch
2. Fuel receptacle cap
3. Fuel receptacle kill cap
BTC– integrated FMM

Refuse box FMM

1

3

2

FIGURE 2–25. Drive Away Protection (DAP) types

1 fuel door switch

Refuse – AUX front bumper fill

2 fuel receptacle cap

3 fuel receptacle kill cap

Please refer to the appropriate DAP type below for identification, location, operation, and circuit schematics.
More than one type of DAP may be installed on the same vehicle. FIGURE 2–26

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Fuel receptacle kill cap

Fuel receptacle kill cap

Fuel door switch

FIGURE 2–26. Multiple Drive Away Protection (DAP) systems on a single refuse truck

Regardless of fuel receptacle or switch type, all DAP circuit sensors are numbered, located, and diagrammed
as follows:

DAP
Circuit #

Location

Circuit schematic

Notes

1

driver side

2

driver side

Refer to DAP 1 & 2
circuit diagram
below

–

3

passenger side

4

passenger side

5

varies, but always
uses a kill cap

–
Refer to DAP 3, 4 &
DAP 5 circuit
diagram below

–
 front bumper fill
 remote fill
 body side fill

Please contact Hexagon Agility® CCTS for specific DAP application details.

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2.6.1 Fuel door switch
Box type FMMs typically incorporate DAP function into the FMM door. When the FMM door is properly closed,
a magnet contacts the reed switch to complete the circuit enabling the engine to start. FIGURE 2–27
The vehicle will not start if the fuel fill door is not completely latched.