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Cummins 5.9L & 6.7L Common Rail Diesel

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Case Study

Bosch fuel systems and Cummins engines come together to create some confusing (and often invisible) Dodge/Ram repair information. Cummins designed the engines, but Dodge wrote the repair information. Problem! Their information lacks any explanation of the purpose of each test, or a clear direction to go with the results. But ATG has a solution!

This manual was designed specifically to give technicians a clear diagnostic path for engine management and emissions concerns.

ATG spent months collecting and comparing technical information to fill in the holes, and then diagnosed and repaired these vehicles to validate everything. This manual is the only place you'll find explanations that not only tell you which tests to run in what order and what the test results should be, but why, and what your options are when a test fails.

Table of Contents Page
Common Rail  
Cummins HPCR Evolution  
Warnings 8
Generations & Overview 8
Significant Changes 9
Things You Need to Know  
Cooling System Issues 10
Late 6.7L Dual Radiators 11
6.7L Cooling System Bleeding 11
Mechanical Faults  12
Warrantying your Engine Work?  12
Identifying Power Up Software 13
Aftermarket ‘Foolers’ & ‘Race’ Valves 13
Mining for Evidence of Abuse 14
Resetting Duty Cycle Accumulators 15
Engine Position Sensors & Codes 16
Which Module Controls What? 16
IPMs, TIPMs & PDCs 17
Crankcase Ventilation 19
Crankcase Pressure Sensor 20
6.7L Crankcase Pressure PIDs 20
Air Intake System  
Basic Intake System  
Overview 22
Inverted MAF Sensor PIDs 24
Intake Air Heater (IAH) 25
IAH PIDs & Controls 26
6.7L Intake Air (IA) Valve/ EGR Throttle Valve  27
5.9L Exhaust Brake  27
6.7L Exhaust Brake  28
6.7L Air Diverter Valve (Cold Air Intake)  29
Turbocharger Overview 30
Charge Air Cooler (CAC) 30
Neutral Turbine Speed Limiting 31
5.9L Boost Control 31
5.9L Turbocharger Lubrication 33
Normal 5.9L Turbocharger & Boost PIDs 33
6.7L Variable Geometry Turbo 34
6.7L Electronic Turbocharger Actuator  35
6.7L Turbo Speed Sensor & Closed Loop Control 36
Normal 6.7L Turbocharger & Boost PIDs 36
6.7L Scan Tool Turbocharger Actuator Calibration 38
Common Turbocharger Faults 39
P2262 Scan Tool Procedure  40
6.7L Turbocharger Cleaning 42
More About the Turbo Cleaning Port 43
More About Turbo Cleaning  44
Fuel Systems  
Complete Supply & Delivery System  
High Pressure Common Rail (HPCR) Overview 45
Low Pressure Fuel Pump Control  46
Low Pressure Fuel Supply System  
2003-2004 Low Pressure Pump 47
2005 & Newer Low Pressure Pump (and Modified 2003 & 2004 Applications) 48
1998-2004 Low Pressure Pump Update/Relocation 48
Fuel Filter Housing 51
OEM vs Aftermarket Fuel Filters 51
6.7L Dual Filters 52
Filter Service 52
Fuel System Priming 52
Fuel Heater  53
Water in Fuel (WIF) Sensor 53
Low Pressure System Restrictions 54
Low Pressure Pump Pressure Test 55
Low Pressure Pump Volume Test 56
2003-2004 Filter-Mounted Pump Vacuum Test 56
High Pressure Fuel System  
High Pressure Side Fuel Flow 57
Bosch CP3 High Pressure Pump – 5.9L  57
Bosch CP3 High Pressure Pump – 6.7L  58
High Pressure Pump Failures 58
Fuel Control Actuator (FCA) – The High Pressure Regulator 59
FCA Failures 59
Cascade Overflow Valve (COV) 60
Cascade Overflow Valve Failures 60
Fuel Rail Pressure (FRP) Sensor 60
Fuel Rail Pressure Sensor Faults 61
Pressure Limiting (Relief) Valve 61
Pressure Limiting Valve Faults 61
Fuel Rail & Lines 62
Fuel Rail & Line Faults 62
Early FCA & Pressure PID Activity  62
Late FCA & Pressure PID Activity  63
Normal High Pressure System Values 66
Fuel Pressure Fault Case Study – 2006 5.9L  67
Scan Tool FCA Solenoid Control 69
Scan Tool High Pressure Control (Fuel Pressure Override) 69
FCA Lab Scope Voltage & Current Test 71
High Pressure System Pressure & Flow Testing Overview 72
High Pressure Pump Cranking Test – No-Start & Hard-Start 73
High Pressure Pump Running Test – Drivability Complaints 73
High Pressure Pump Maximum Pressure (Dead-Head) Test 74
High Pressure Pump Flow Test 74
Pressure Limiting Valve Flow Test 75
High Pressure Pump/COV Return Rate Test 76
Direct Fuel Injectors 77
5.9L Injectors & Control 78
6.7L Injectors & Control 79
Injector Transfer Tubes 80
Injector Harness/Valve Cover Gasket 82
Injector Faults 83
Injector Scan Tool Test (Cylinder Performance Test) 84
Scan Tool Injector Kill 85
5.9L Scan Tool Injector Kill Numbering Issues 86
Injector Body Leak Test 86
6.7L Injector Quantity Adjustment (IQA) Programming 87
Injector Return Rate Concept & Tools 88
Make Your Own Block-Off Plugs – It’s Free! 89
Making Sense of OEM Return Rate Procedures 90
Injector Return Rate Test Procedure 91
No-Starts:  Avoiding Return Rate Testing 93
High Return Rates:  Sell 1 or 6? 94
Avoiding Return Rate Testing Based on Likely Sales Outcome 94
Lab Scope Fuel Injector Testing 94
Injector Lab Scope Test Connections 95
Identifying 5.9L Injector Circuit Activity 95
5.9L Injector Lab Scope Voltage Examples 96
5.9L Injector Lab Scope Current Examples 97
5.9L Voltage & Current Comparison 99
6.7L Injector Lab Scope Voltage & Current Examples 101
Symptom Testing Strategies - ATG Symptom Tests 103
Cummins Six-Step Diagnosis 103
How to Use ATG Symptom Tests  104
No-Start, No-Communication 104
No-Start  105
Hard-Start – Cold Only  108
Hard-Start or Start & Stall  109
Hesitation, Sag, Stumble  112
Misfire or Rough Idle  113
Misfiring with White Smoke  115
Stalling 115
Surging  116
Surging Special Case:  Racing Engine, High Commanded Fuel Pressure 117
Poor Fuel Economy 118
Low Power 119
Black Smoke 121
White Smoke 122
Blue/Gray Smoke 123
Engine Noises 124
High Oil Level 125
Cylinder-Sealing Faults  126
Relative Compression Test 126
Crankcase Pressure – The Relative Compression Alternative 127
Hard-Start Cold, Rough Idle Cold Case Study 128
Low Power Case Study #1 130
Low Power Case Study #2 132
Emissions Systems  
Exhaust Gas Recirculation (EGR) Overview 133
3-Phase DC EGR Motor 133
5-Volt EGR Power Supply? 134
EGR Temperature Sensor 134
Identifying EGR Delete Kits 134
EGR Cooler 135
EGR Cooler Bypass Valve 136
EGR Airflow Control Valve 136
Exhaust Backpressure Sensor  137
EGR System Faults 138
EGR System PIDs  139
Aftertreatment Systems Overview  
Many, Many Things 143
Aftertreatment Component Summary 143
6.7L Exhaust Gas Temperature (EGT) Sensors 145
5.9L Catalytic Converter  
Why You Are Not Very Concerned 147
Diesel Oxidation Catalyst (DOC)/Close Coupled Catalyst (CCC)  
Overview 148
DOC Faults 148
DOC Quick Check 150
6.7L NOX Adsorber Catalyst (NAC)  
Sulfur Loading & Regeneration 151
Oxygen Sensors  151
Oxygen Sensor Module  152
NAC & Oxygen Sensor Faults 153
P2000, P2A00 and/or P2A01 TSB:  Clean Sensors & Wrap Exhaust 153
Oxygen Sensor Codes TSB 154
NAC Diagnosis 154
Scan Tool NOX Adsorber Counter Reset 156
Diesel Particulate Filter (DPF)  
Overview  157
Closed Loop:  DPF Differential Pressure Sensor  157
Regeneration & DPF Service Life 158
DPF Faults 158
Reprogramming for Emissions Codes 159
Passive vs. Active vs. Stationary Regeneration 159
Electronic Vehicle Information Center (EVIC) Messages  160
Exhaust Air Cooler (Diffuser) 161
Stationary Regeneration (Desoot) 161
When Regeneration Goes Wrong 162
The Role of the DOC/CCC 165
Post-Stationary Regeneration Resets 165
Selective Catalyst Reduction (SCR) & Diesel Exhaust Fluid (DEF)  
Systems Overview 166
SCR Operation 166
Module, Module & Modules 167
Refilling the DEF (Reductant) Tank 168
Closed Loop Control – NOX Sensors 169
Ammonia Sensor & Module 170
Dosing Control Unit (DCU) 170
DEF Pump Module 170
DEF Injector (SCR Dosing Valve) & Heated Lines 171
DEF Tank & Component Cleaning 172
DEF Heaters 172
DEF Pump Testing  172
Scan Tool & Mechanical DEF Injector Testing 172
DEF Level Sensor 173
DEF Level EVIC Warning Messages 173
DEF Quality EVIC Warning Messages/Inducement Strategy 173
DEF Faults & Issues 174
Basic DEF & SCR PIDs 175
Reference Information - Wiring Examples  
5.9L Engine Performance & Emissions  177
6.7L Fuel Injectors  178
6.7L Turbocharger & Intake  182
6.7L EGR System 184
6.7L Emissions Systems (2007-2012 Systems) 187
6.7L Emissions Systems (2013 & Newer Systems)  188

The case study shown below shows a test drive for a low power complaint on a Cummins 5.9L. At low loads and speeds, the fuel pressure regulator (FCA solenoid) is almost normal at 32%, and the rail pressure is close to the desired ('SET') pressure. However, at higher speeds and loads (cursor), the high pressure was 10,000 PSI less than the set point! The FCA solenoid command dropped to 0% to increase fuel flow to the high pressure pump pistons, but it wasn't enough.


Low Fuel Pressure @ Speed and Load


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