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Hexagon MT-45 Service Manual Download Page 12

DSM.0008 Ver 1.0

FCCC MT-45 / MT 55 CNG Diagnostics Service Manual

February 15, 2022

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RINTED AND

D

OWNLOADED

C

OPIES ARE

N

OT

C

ONTROLLED

FCCC MT CNG

12

FCCC MT CNG

DSM.0008 Ver 1.0

FCCC MT-45 / MT 55 CNG Diagnostics Service Manual

February 24, 2022

P

RINTED AND

D

OWNLOADED

C

OPIES ARE

N

OT

C

ONTROLLED

12

Fuel System Troubleshooting and Diagnostics

ISSUE: 

Poor engine performance (rough idle, lacks power, hesitation, stalls)

Issue

Remedy

Low pressure side of fuel system is less than 

125 psi 

(8.62 Bar)

•

LP fuel hose restriction

•

LP fuel filter clogged

•

HP fuel filter clogged

•

HP / LP fuel tubes kinked/bent

•

pressure regulator fault 

•

fuel injector(s) fault

• Refer to Engine Misfire Diagnostic procedure section(s) below. 

•

Ignition system fault

•

Induction system restriction

•

Exhaust system restriction

•

Mechanical engine failures

•

Engine sensor fault

• Refer to OEM procedure. 

Summary of Contents for MT-45

Page 1: ...008 Ver 1 0 FCCC MT 45 MT 55 CNG Diagnostics Service Manual February 24 2022 PRINTED AND DOWNLOADED COPIES ARE NOT CONTROLLED 1 Diagnostic Service Manual Freightliner Custom Chassis Corporation FCCC M...

Page 2: ...tained by contacting Freightliner Customer Chassis Corporation FCCC Fuel system warranty or non warranty product support may be obtained by calling or emailing Hexagon Agility Customer Care and Techni...

Page 3: ...Personnel 6 Safety Equipment 6 General Safety Precautions 7 Vehicle Fire Procedure 8 First Responder Guide 8 Codes and Compliances 8 Return to Service Inspection 8 Fuel System Schematic 9 Fuel System...

Page 4: ...IPC instrument panel cluster ASM assembly LP low pressure Bar metric unit of pressure MIL malfunction indicator light CGA Compressed Gas Association NFPA National Fire Protection Association CNG comp...

Page 5: ...for controlled evacuation flaring under certain environmental conditions Hexagon Agility minimizes these potential hazards through state of the art design and testing practices Always observe the pro...

Page 6: ...and visible throughout all servicing and fueling areas Verify fire extinguishers are charged up to date and rated correctly 3 In case of emergency self contained breathing apparatus should be on site...

Page 7: ...areas that comply will all federal state and municipal laws and regulations 7 When performing service or repairs to any portion of the fuel system install proper lockout tagout LOTO device and observe...

Page 8: ...andate Side CNG decals must be installed adjacent to vehicle DOT number Codes and Compliances For complete and detailed information concerning CNG codes and regulations please refer to the following U...

Page 9: ...ONTROLLED 9 FCCC Fuel System Schematics Item Description 1 fuel fill panel 2 HP flexible fuel hose 3 1 4 turn manual shutoff valve 4 high pressure HP fuel filter 5 pressure regulator 6 supply solenoid...

Page 10: ...rvice Manual February 24 2022 PRINTED AND DOWNLOADED COPIES ARE NOT CONTROLLED 10 FCCC Fuel System Schematics Fuel Storage System Item Description 1 cylinders 2 cylinder manual valves 3 PRDs 4 PRD ada...

Page 11: ...ptacle Issue Solution Fuel fill receptacle O ring frozen due to gas expansion Close cylinder manual valve s Wait for receptacle to warm to ambient temperature to check if leak persists Use a slow fill...

Page 12: ...and Diagnostics ISSUE Poor engine performance rough idle lacks power hesitation stalls Issue Remedy Low pressure side of fuel system is less than 125 psi 8 62 Bar LP fuel hose restriction LP fuel fil...

Page 13: ...IES ARE NOT CONTROLLED 13 J3 OEM ECU connector located at DS radiator core support Refer to OEM manual for pin out C1 Electronic Control Module ECM connector located inside at driver footwell C2 Elect...

Page 14: ...id Ground located on frame between pressure regulator and 1 4 turn manual shutoff valve P31 Pressure Transducer connector located on pressure regulator Y41 Supply Solenoid connector located on pressur...

Page 15: ...3 NA 4 316 GRY Pressure Signal 1 4 2 ECM C2 connector pin out IO31 Start Confirm pin out Cavity Circuit Color Description A 313 PUR Start Relay Confirm A Electrical 9 2 7 6 3 8 10 14 15 16 Cavity Circ...

Page 16: ...rcuit Color Description 1 409 BRN Low Reference 2 316 GRY Pressure Signal 3 604 RED 5V Reference 1 2 3 P31 connector pin out Cavity Circuit Color Description A 409 BLUE Low Reference IO30 Crank Reques...

Page 17: ...ty Circuit Color Description A 312 GRN Drive Away Protection D81 DAP Drive Away Protection Cavity Circuit Color Description A 104 BLK Supply Solenoid Ground B 315 WHT Fuel Gauge Signal C 406 TAN Fuel...

Page 18: ...than 600 psi 41 3 Bar is indicated on the HP fuel gauge Possible causes include the following 1 Power or ground insufficient at pressure transducer 2 Power or ground insufficient on connector for ECM...

Page 19: ...ircuit Low FMI 7 Fuel Level Sensor A Circuit Range Performance Fault Codes The following fault code s may set when vehicle ignition is left in the ON position while the driver does not engage the star...

Page 20: ...und pressurized fuel systems Verify parking brake is engaged wheels are chocked and ignition switch is in OFF position Tools and Supplies General Safety Precautions Item Purpose safety glasses eye pro...

Page 21: ...ange proceed to Circuit System Testing 5 Clear fault codes 6 Operate the vehicle in the same conditions for enabling the fault code or within the same conditions that triggered the fault code based on...

Page 22: ...D AND DOWNLOADED COPIES ARE NOT CONTROLLED 22 C1 Electronic Control Module ECM connector located inside at driver footwell C2 Electronic Control Module ECM connector located inside at driver footwell...

Page 23: ...February 24 2022 PRINTED AND DOWNLOADED COPIES ARE NOT CONTROLLED 23 Splice 1 located near F78 Fuel System Harness Interface Splice 2 located near 1 4 turn manual shutoff valve Splice 3 located insid...

Page 24: ...on with anything other than an appropriately sized shaped test Doing so may result in damage to components Fuel Gauge Electrical Schematic Fuel Pressure Sensor Schematic F78 Fuel System Harness to OEM...

Page 25: ...DOWNLOADED COPIES ARE NOT CONTROLLED FCCC MT CNG 25 FCCC MT CNG DSM 0008 Ver 1 0 FCCC MT 45 MT 55 CNG Diagnostics Service Manual February 24 2022 PRINTED AND DOWNLOADED COPIES ARE NOT CONTROLLED 25 F...

Page 26: ...WNLOADED COPIES ARE NOT CONTROLLED FCCC MT CNG 26 FCCC MT CNG DSM 0008 Ver 1 0 FCCC MT 45 MT 55 CNG Diagnostics Service Manual February 24 2022 PRINTED AND DOWNLOADED COPIES ARE NOT CONTROLLED 26 pres...

Page 27: ...te If equal to 4 8 5 2V Proceed to Step 4 If less than 4 8V Proceed to Step 5 If greater than 5 2V Proceed to Step 19 9 Step 1 Does the vehicle start and run Yes Proceed to Step 2 No Proceed to Step 1...

Page 28: ...ES ARE NOT CONTROLLED 28 Step 4 Ignition OFF Reconnect ECM connector C1 Using a DMM back probe ECM connector C2 Cavity 1 Brown and C2 Cavity 4 Gray Ignition ON within 30 seconds measure and record vol...

Page 29: ...ss Interface F79 connector Terminal B Pink White and Terminal C Pink White Voltage is between 4 8 5 2V Proceed to Step 6 Voltage is not between 4 8 5 2V Refer to OEM chassis diagnostics for further in...

Page 30: ...connector still disconnected ECM connector C1 still disconnected Measure resistance between connector F78 Terminal C Tan and connector C1 Terminal 9 Tan Resistance is less than 10 ohms Proceed to Ste...

Page 31: ...re Step 11 Continued from Step 9 Connector P31 still disconnected Ignition ON within 30 seconds measure for battery voltage between connector P31 Terminal 3 Red and known good ground Voltage is betwee...

Page 32: ...C diagnostic manual Perform System Verification Procedure Step 14 Ignition OFF reconnect connector F78 F79 ECM connector C1 still disconnected Ignition ON within 30 seconds measure voltage between con...

Page 33: ...resistance in circuit 204 between C1 Terminal 8 and Splice 3 Refer to DSM 0036 Perform System Verification Procedure Voltage not equal to battery voltage Proceed to Step 17 Step 17 Ignition OFF discon...

Page 34: ...22 PRINTED AND DOWNLOADED COPIES ARE NOT CONTROLLED 34 Step 18 Continued from Step 4 Ignition OFF Ensure ECM connector C1 is connected Back probe C1 Cavity 9 Tan and C1 Cavity 10 White Ignition ON wit...

Page 35: ...p 3 Ignition OFF with connector C1 still disconnected Disconnect connector F78 Measure resistance between connector F78 Terminal B White and connector F78 Terminal D Pink Resistance is less than 10 oh...

Page 36: ...ction A Crank No Start condition exists when ignition power is present to turn the engine via the starter and the engine cranks but the engine will not fire Possible causes include the following close...

Page 37: ...pressure gauge 0 200 psi 0 13 8 Bar standard fuel test gauge 0 200 psi 0 13 8 Bar mirror observe backside of fittings while performing leak check spark tester used to detect ignition or spark failure...

Page 38: ...DSM 0008 Ver 1 0 FCCC MT 45 MT 55 CNG Diagnostics Service Manual February 24 2022 PRINTED AND DOWNLOADED COPIES ARE NOT CONTROLLED 38 Connector Location View 8 Crank No Start 6 G21 Supply Solenoid Val...

Page 39: ...cs Service Manual February 24 2022 PRINTED AND DOWNLOADED COPIES ARE NOT CONTROLLED 39 Crank No Start Electrical Schematic F78 Fuel System Harness to OEM Harness Interface G20 Fill Panel Ground C1 Ele...

Page 40: ...ess than 600 psi 41 3 Bar Fuel to 600 psi retry crank More than 600 psi 41 4 Bar Proceed to Step 3 Step 1 Verify driver side DS and passenger side PS cylinder valves are in open position Both valves a...

Page 41: ...is not present Refer to OEM manual Spark is present Proceed to Step 5 Step 5 Remove harness connector from a rear fuel injector of each cylinder bank Use noid light to check for power at each fuel in...

Page 42: ...1 Pink and 2 Black Battery voltage present Replace pressure regulator Battery voltage not present Proceed to Step 8 Step 8 Check for battery voltage from Y41 connector Terminal 1 Pink to known good g...

Page 43: ...onnect tool Step 11 Install a commercially available fuel pressure test port adaptor and gauge rated for at least 150 psi 10 3 Bar from fuel rail to LP fuel hose Test tool installed Proceed to Step 12...

Page 44: ...han 120 psi 8 3 Bar Proceed to Step 13 Step 14 Remove LP fuel hose from LP fuel filter Remove LP fuel hose from fuel line adaptor tool using the line disconnect tool With the LP fuel hose removed use...

Page 45: ...CONTROLLED 45 Crank No Start Step 15 Inspect HP and LP filters for blockage Refer to Filter Element Replacement section for disassembly and assembly instructions Debris found Replace element clean fil...

Page 46: ...Retry crank If vehicle starts proceed to Step 17 If vehicle does not start close 1 4 turn manual shutoff valve Reprogram replace ECM Perform System Verification Procedure Pressure is less than 120 ps...

Page 47: ...NOT CONTROLLED 47 No Crank No Start No Crank No Start Introduction A No Crank No Start condition exists when the engine will not start and there is no response when the ignition is turned to the cran...

Page 48: ...system components before and after repair flashlight illuminate components mirror observe backside of fittings while performing leak check Digital Multimeter DMM resistance and voltage measurements PS...

Page 49: ...rvice Manual February 24 2022 PRINTED AND DOWNLOADED COPIES ARE NOT CONTROLLED 49 C1 Electronic Control Module ECM connector located inside at driver footwell IO31 Start Confirm connector located insi...

Page 50: ...MT CNG 50 FCCC MT CNG DSM 0008 Ver 1 0 FCCC MT 45 MT 55 CNG Diagnostics Service Manual February 24 2022 PRINTED AND DOWNLOADED COPIES ARE NOT CONTROLLED 50 F78 Fuel System Harness Interface located n...

Page 51: ...t Electrical Schematic F78 Fuel System Harness to OEM Harness Interface G20 Fill Panel Ground C1 Electronic Control Module G21 Supply Solenoid Ground Y41 Supply Solenoid Splice 1 Splice 3 Splice 2 Fue...

Page 52: ...tics Service Manual February 24 2022 PRINTED AND DOWNLOADED COPIES ARE NOT CONTROLLED 52 Splice 2 located inside harness along frame rail near 1 4 turn manual shutoff valve Splice 3 located inside har...

Page 53: ...CNG 53 FCCC MT CNG DSM 0008 Ver 1 0 FCCC MT 45 MT 55 CNG Diagnostics Service Manual February 24 2022 PRINTED AND DOWNLOADED COPIES ARE NOT CONTROLLED 53 C1 connector IO30 crank request IO31 start conf...

Page 54: ...cedure Retry crank If no crank proceed to Step 3 Battery voltage greater than is 12 2V Proceed to Step 3 Step 1 Is the fuel cap installed completely Drive away protection DAP will prevent the engine f...

Page 55: ...the OEM start relay connector Orange Disconnect IO30 connector from the OEM start relay connector Orange Connect OEM start relay connectors Orange together Crank vehicle Engine does not crank Follow...

Page 56: ...connector C1 Terminal 2 Purple Continuity is not present Repair high resistance in circuit 313 between C1 and IO31 Connectors Refer to DSM 0036 Perform System Verification Procedure Continuity is pres...

Page 57: ...age between connector C1 Terminal 8 Pink and a known good ground Voltage equal to battery voltage Repair high resistance in circuit 104 between C1 and Splice 1 Refer to DSM 0036 Perform System Verific...

Page 58: ...on circuit 204 between F78 and Splice 2 Refer to DSM 0036 Perform System Verification Procedure No Crank No Start Step 10 Ignition OFF disconnect Y41 connector Ignition ON within 30 seconds measure vo...

Page 59: ...wn good ground Attempt to start vehicle Vehicle does not start Repair open circuit 312 between C1 and terminals 14 15 and 7 including Splice 4 through D81 Refer to DSM 0036 Perform System Verification...

Page 60: ...15 2022 PRINTED AND DOWNLOADED COPIES ARE NOT CONTROLLED FCCC MT CNG 60 FCCC MT CNG DSM 0008 Ver 1 0 FCCC MT 45 MT 55 CNG Diagnostics Service Manual February 24 2022 PRINTED AND DOWNLOADED COPIES ARE...

Page 61: ...ignition is left in the ON position while the driver does not engage the starter within approximately 30 seconds SPN FMI Type MIL Possible Faults 1322 31 B Yes Fuel injector malfunction A vehicle that...

Page 62: ...stems Verify parking brake is engaged wheels are chocked and ignition switch is in OFF position Tools and Supplies General Safety Precautions Item Purpose safety glasses eye protection shop rags clean...

Page 63: ...connectors not found Proceed to Step 3 Step 1 Start and idle vehicle The vehicle exhibits a misfire condition Proceed to Step 2 The vehicle does not exhibit a misfire condition Operate the vehicle un...

Page 64: ...n coil packs damaged or worn spark plug wires bad spark plugs Damaged parts located Repair damaged part Perform System Verification Procedure No damaged parts Proceed to Step 7 Step 8 Remove LP fuel h...

Page 65: ...n Fuel pressure is not between 120 130 psi 8 27 8 96 Bar Proceed to Step 12 Step 9 Install a commercially available fuel pressure test port adaptor and gauge rated for at least 150 psi 10 3 Bar from f...

Page 66: ...ons Proceed to Step 15 Debris not found Replace element clean filter bowl and reassemble per filter element replacement instructions Proceed to Step 15 Engine Misfire Diagnostics Step 13 Remove LP fue...

Page 67: ...dition not present Proceed to Step 20 Pressure is less than 120 psi 8 3 Bar Replace regulator Perform System Verification Procedure Step 17 With all lines and connections secured pressurize system as...

Page 68: ...tics Step 21 Complete depressurization procedure per Step 11 Remove fuel line adaptor tool from fuel rail and LP fuel hose Reinstall LP fuel hose on fuel rail quick disconnect fitting Complete Leak Ch...

Page 69: ...D FCCC MT CNG 69 FCCC MT CNG DSM 0008 Ver 1 0 FCCC MT 45 MT 55 CNG Diagnostics Service Manual February 24 2022 PRINTED AND DOWNLOADED COPIES ARE NOT CONTROLLED 69 Fuel System Depressurization Depressu...

Page 70: ...eneral Safety Precautions Item Purpose safety glasses eye protection shop rags clean fuel system components before and after repair flashlight illuminate components mirror observe backside of fittings...

Page 71: ...ED COPIES ARE NOT CONTROLLED 71 Step 2 Close passenger side manual shutoff valve NOTE PS cylinder shield access hole similar to DS Step 1 Close driver side cylinder manual shutoff valve Fuel System De...

Page 72: ...tep 3 Verify 1 4 turn manual shutoff valve is open Fuel System Depressurization FRONT 1 4 turn manual shutoff valve Step 4 Start vehicle and allow engine to run until it stalls Attempt to start crank...

Page 73: ...fuel filter Fuel System Depressurization pressure relief port cap pressure relief nut cap HP fuel filter bleed valve Store pressure relief port cap and pressure relief nut cap for reinstallation later...

Page 74: ...ve positive shutoff per Swagelok instructions bleed valve pressure relief nut Pressure relief port cap and pressure relief nut cap must be installed to prevent foreign object debris FOD intrusion If p...

Page 75: ...ARE NOT CONTROLLED FCCC MT CNG 75 FCCC MT CNG DSM 0008 Ver 1 0 FCCC MT 45 MT 55 CNG Diagnostics Service Manual February 24 2022 PRINTED AND DOWNLOADED COPIES ARE NOT CONTROLLED 75 Fuel System Defuelin...

Page 76: ...in wrenches QTY 2 remove and replace bleed valve and defuel adapter torque wrench torque bleed valve 11 16 in socket torque bleed valve CNG defueling kit p n 69500019 CNG defueling defuel hose 35 ft...

Page 77: ...ONTROLLED 77 Step 1 If HP fuel gauge does not read approximately zero perform Fuel System Depressurization procedure Fuel System Defueling FRONT Fuel system must be fully depressurized before defuelin...

Page 78: ...to fitting O ring before installing Verify O ring and sealing surfaces are clean and free of debris Torque fitting to 25 ft lbs 33 9 Nm HP fuel filter defuel hose fitting FRONT Tighten fittings accord...

Page 79: ...dispenser or vent stack Attach NGV connector end of defuel hose adapter to defuel hose Fuel System Defueling Always ground vehicle during defueling vent stack pipe properly supported 10 ft 3m above f...

Page 80: ...ED AND DOWNLOADED COPIES ARE NOT CONTROLLED 80 Step 8 Open manual valve on fuel dispenser or vent stack Fuel System Defueling fuel dispenser vent stack Step 9 Open driver side and passenger side cylin...

Page 81: ...leak Step 11 Slowly open valve on defuel adapter hose Fuel System Defueling Verify defuel hose connections and any other disturbed fittings are not leaking Follow leak check procedure DSM 0037 before...

Page 82: ...CONTROLLED 82 Step 14 Remove defuel hose from defuel hose adapter Detach ground cable clips from vehicle ground and fuel dispenser or vent stack Step 13 Disconnect defuel hose from fuel dispenser or...

Page 83: ...D COPIES ARE NOT CONTROLLED 83 Step 16 Use an 11 16 in wrench to remove fitting from HP fuel filter Fuel System Defueling Step 17 Reconnect defuel hose fitting to defuel hose adapter tighten finger ti...

Page 84: ...relief nut on bleed valve using a 7 16 in wrench To increase service life ensure proper valve performance and prevent leakage apply only enough torque to pressure relief nut as is required to achieve...

Page 85: ...15 2022 PRINTED AND DOWNLOADED COPIES ARE NOT CONTROLLED FCCC MT CNG 85 FCCC MT CNG DSM 0008 Ver 1 0 FCCC MT 45 MT 55 CNG Diagnostics Service Manual February 24 2022 PRINTED AND DOWNLOADED COPIES ARE...

Page 86: ...orque wrench Swagelok Snoop or equivalent leak detection fluid Formula 365 p n 10802096 perform leak test filter element service kit p n 69000481 filter element O ring 55 mm crowfoot wrench used with...

Page 87: ...r components Item Part Description QTY 1 ASM HP fuel filter CNG includes 2 3 QTY 2 5 6 8 9 11 12 13 and mounting hardware not shown 1 2 Filter head CNG POA 1 1 3 ASM bleed valve 1 4 Filter element CNG...

Page 88: ...ment Replacement Low pressure fuel filter components Item Part Description QTY 1 ASM LP fuel filter CNG includes 2 3 4 5 6 9 10 and mounting hardware 1 2 Filter head CNG POA 1 1 3 Fitting 90 degree el...

Page 89: ...D DOWNLOADED COPIES ARE NOT CONTROLLED 89 Filter Element Replacement Step 2 Remove bowl from filter assembly using a 55 mm crow foot wrench ALWAYS verify fuel system has been depressurized Step 3 Remo...

Page 90: ...t and residue using a clean dry shop towel Filter Element Replacement Step 6 Inspect filter assembly including stem O ring sealing surfaces and threads for damage or wear Step 7 Prepare filter element...

Page 91: ...tics Service Manual February 24 2022 PRINTED AND DOWNLOADED COPIES ARE NOT CONTROLLED 91 Step 10 Install lubed O ring into the filter bowl groove Filter Element Replacement Step 11 Finger tighten bowl...

Page 92: ...4 2022 PRINTED AND DOWNLOADED COPIES ARE NOT CONTROLLED 92 Filter Element Replacement Step 13 Apply leak check solution to all fittings on the filter assembly to check for leaks Step 12 Torque filter...

Page 93: ...lter Element Replacement Step 15 Inspect filter assembly for leaks Bubbles from solution will indicate leak s Leaks found Proceed to Step 16 No leaks found Procedure complete ALWAYS verify fuel system...

Page 94: ...PIES ARE NOT CONTROLLED 94 Filter Element Replacement Step 18 Apply leak check solution to all fittings circled on the filter assembly to check for leaks Step 20 Inspect filter assembly for leaks Leak...

Page 95: ...dure After completing all repairs always perform the following Steps to confirm the issue is fixed 1 Reconnect all connectors and verify connections are secure 2 Reattach any enclosure covers and veri...

Page 96: ...2022 PRINTED AND DOWNLOADED COPIES ARE NOT CONTROLLED FCCC MT CNG 96 FCCC MT CNG DSM 0008 Ver 1 0 FCCC MT 45 MT 55 CNG Diagnostics Service Manual February 24 2022 PRINTED AND DOWNLOADED COPIES ARE NO...

Page 97: ...2022 PRINTED AND DOWNLOADED COPIES ARE NOT CONTROLLED FCCC MT CNG 97 FCCC MT CNG DSM 0008 Ver 1 0 FCCC MT 45 MT 55 CNG Diagnostics Service Manual February 24 2022 PRINTED AND DOWNLOADED COPIES ARE NO...

Page 98: ...port support hexagonagility com Parts Orders parts hexagonagility com Proprietary Statement The information provided within this document is proprietary and confidential All prior versions including u...

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