DSM.0125 Ver. 3.0  April 26, 2023

Diagnostic, service, maintenance, and inspection manual for 366-series ProCab® behind the cab (BTC) compressed natural gas (CNG) fuel systems equipped with Blue iQ™.

Description and Operation Overview


    Service Intervals

    Depressurization Procedure

    Defuel Procedures

        Vent to Atmosphere

        Fuel Transfer 

    Excess Flow Valve Reset Procedure

    PRD Vent Cap Replacement

    Manifilter Element Replacement 

    Inspection Types and Intervals

        Initial Delivery Inspection

        Driver Daily Checklist

        Six Month Inspection

        Cylinder Inspection

        Fuel System Inspection

            Bushing Ring and Isolator Inspection

            Fuel Hose Inspection

    TruckWings™ Preventative Maintenance

Symptom-based Diagnostics

    No Crank, No Start Diagnostic

    Crank, No Start Diagnostic

    Drivability Diagnostic

    OEM Fuel Gauge Inoperative Diagnostic

    Rear View Camera Inoperative Diagnostic

Blue iQ Fault Code Diagnostics

Blue iQ™ Fault Code List

Blue iQ™ Fault Code Diagnostic Procedures

Repair and Replacement Procedures

    Blue iQ™ Smart Gauge    

    Fuel Management Module (FMM) Components

        Fuel System Control Module (FSCM)        

        1/4-turn manual shutoff valve

        Standard NGV1 fill receptacle or fast fill receptacle

        Fuel receptacle cover

        Reed switch

        Kill cap

        High-pressure (HP) fuel gauge or low-pressure (LP) fuel gauge

        Manifilter assembly

        Supply solenoid valve (SSV) - standard pressure regulator (standalone)

        Supply solenoid valve (SSV) coil - standard pressure regulator (standalone)

        Supply solenoid valve (SSV) post and operator replacement - standard pressure regulator

        Supply solenoid valve (SSV) - Marathon pressure regulator (integrated)

        Supply solenoid valve (SSV) coil - Marathon pressure regulator (integrated)

        Pressure regulator - standard (black)

            Coolant Leak Repair - standard pressure regulator

        Pressure regulator - Marathon (anodized red)

        Pressure / temperature transducer

        Bleed valve

        Defuel valve

        Defuel receptacle


    Fuel Storage System Components


            Cylinder composite repair

            Cylinder boss repair

        Cylinder valve

        Cylinder plug

        Remote PRD

        Cylinder neck mount block - fixed (valve) end

       Cylinder neck mount block - sliding (plug) end 

        Cylinder neck mount block bushing



        Fuel cabinet side cover

    Wiring and Harness

    Fuel System Accessories


        LED utility lights

        Grab handles

        Glad hands holder

        OEM accessory mount

        Rear view camera

        Auxiliary Power Unit (APU)

CNG Special Service Tools    

Removing a Vehicle from Service  

Glossary of Terms

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