PDF Service Manual Cummins CM850 Electronic Control System - 5 MB
This comprehensive, multi-volume service manual covers the Cummins CM850 Electronic Control System used on a wide range of engines, including the ISB, QSB, ISC, QSC, and ISL series.
It is the definitive guide for diagnosing and repairing electronic faults within these advanced engine systems.
Technicians will find detailed troubleshooting trees, wiring diagrams, and sensor specifications.
This manual is essential for anyone servicing modern Cummins diesel engines.
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--- Page 1 ---
Troubleshooting and Repair Manual
ISB, ISBe2, ISBe3, ISBe4, QSB4.5, QSB5.9,
QSB6.7, ISC, QSC8.3, ISL, ISLe3, ISLe4, and
QSL9, CM850 Electronic Control System
Volume 1
--- Page 3 ---
Engine Diagrams ISB, ISBe2, ISBe3, ISBe4, QSB4 [...]
Page E-6 Section E - Engine and System Identification
Engine Diagrams
Engine Views
With CM850
Rear View (ISC, QSC8.3, ISL, and QSL9)
1 Engine lifting bracket
2 Crankcase breather
3 Turbocharger speed sensor (only on variable geometry turbochargers)
4 Turbocharger (variable geometry turbocharger shown)
5 Injector drain line connection
6 Flywheel housing
7 Flywheel
8 Engine oil drain plug
9 OEM fuel supply line connection
10 OEM fuel drain line connection
11 Air intake connection.
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--- Page 4 ---
Engine Diagrams ISB, ISBe2, ISBe3, ISBe4, QSB4 [...]
Page E-38 Section E - Engine and System Identification
Notes
--- Page 5 ---
ISB, ISBe2, ISBe3, ISBe4, QSB4 [...]
Page TF-2 Section TF - Troubleshooting Fault Codes
FAULT CODE 0001 - Exhaust Gas Pressure Sensor Number 1 Circuit - Voltage
Above Normal, or Shorted to High Source
TROUBLESHOOTING SUMMARY
STEPS SPECIFICATIONS SRT CODE
STEP 1: Check the exhaust gas pressure sensor and circuit.
STEP 1A: Inspect the exhaust gas Dirty or damaged pins?
pressure sensor and connector
pins.
STEP 1B: Check the circuit response. Fault Code 0001 inactive and
Fault Code 0002 active?
STEP 1C: Check the sensor supply 4.75 to 5.25 VDC?
voltage and return circuit.
STEP 1D: Check the fault code and verify Fault Code 0001 present?
sensor condition.
STEP 2: Check the exhaust gas treatment monitor unit and exhaust gas treatment
monitor harness.
STEP 2A: Inspect the exhaust gas Dirty or damaged pins?
treatment monitor unit and
exhaust gas treatment monitor
harness connector pins.
STEP 2B: Check for an open circuit in the Less than 10 ohms?
exhaust gas treatment monitor
harness.
STEP 2C: Check for a pin-to-pin short Greater than 100k ohms?
circuit in the exhaust gas
treatment monitor harness.
STEP 2D: Check for a pin-to-pin short Greater than 100 ohms?
circuit in the exhaust gas
treatment monitor harness.
STEP 2E: Check for fault code presence. Fault Code 0001 present?
STEP 3: Clear the fault code.
STEP 3A: Disable the fault code. Fault Code 0001 present?
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--- Page 6 ---
ISB, ISBe2, ISBe3, ISBe4, QSB4 [...]
Page TF-34 Section TF - Troubleshooting Fault Codes
STEP 2: Check the exhaust gas treatment monitor unit and exhaust gas treatment
monitor harness.
STEP 2A: Inspect the exhaust gas treatment monitor unit and exhaust gas treatment monitor harness
connector pins.
Condition:
• Turn keyswitch OFF
• Disconnect the exhaust gas treatment monitor unit from the exhaust gas treatment monitor harness.
Action Specification/Repair Next Step
Inspect the exhaust gas treatment monitor unit Dirty or damaged pins? 3A
and exhaust gas treatment monitor harness YES
connector pins for the following:
• Loose connector Repair:
• Corroded pins A damaged connection has been detected in
• Bent or broken pins the exhaust gas treatment monitor unit
• Pushed back or expanded pins connector or exhaust gas treatment monitor
• Moisture in or on the connector harness connector.
• Missing or damaged connector seals
• Dirt or debris in or on the connector pins Clean the connector and pins.
• Connector shell broken Repair the damaged harness, connector or
• Wire insulation damage pins if possible. Use the following
• Damaged connector locking tab. procedure(s) in the Troubleshooting and
Use the following procedure for general Repair Manual ISC, ISCe, QSC8.3, ISL and
inspection techniques. Refer to Procedure QSL9 Engines, Bulletin 4021418.
019-361 in Section 19. • Refer to Procedure 011-038 in Section 11.
• Refer to Procedure 011-035 in Section 11.
Dirty or damaged pins? 2B
NO
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--- Page 7 ---
ISB, ISBe2, ISBe3, ISBe4, QSB4 [...]
Page TF-66 Section TF - Troubleshooting Fault Codes
FAULT CODE 123 - Intake Manifold Pressure Sensor Circuit - Voltage Below
Normal or Shorted to Low Source
TROUBLESHOOTING SUMMARY
CAUTION
To reduce the possibility of damaging a new ECM, all other active fault codes must be investigated prior to
replacing the ECM.
CAUTION
To reduce the possibility of pin and harness damage, use the following test leads when taking a
measurement:Part Number 3164596 - male Framatome test leadPart Number 3822917 - female Deutsch/AMP/
Metri-Pack test lead.
STEPS SPECIFICATIONS SRT CODE
STEP 1: Check the fault codes.
STEP 1A: Check for sensor supply fault Fault Code 187 active?
codes.
STEP 1B: Check for an inactive fault code. Fault Code 123 inactive?
STEP 2: Check the intake manifold pressure sensor and circuit.
STEP 2A: Inspect the intake manifold Dirty or damaged pins?
pressure sensor and connector
pins.
STEP 2B: Check the sensor supply 4.75 to 5.25 VDC?
voltage and return circuit.
STEP 2C: Check the circuit response. Fault Code 122 active and Fault
Code 123 inactive?
STEP 2D: Check the fault codes and verify Fault Code 123 active?
sensor condition.
STEP 3: Check the engine control module and engine harness.
STEP 3A: Inspect engine control module Dirty or damaged pins?
and engine harness connector
pins.
STEP 3A-1: Check the sensor supply 4.75 to 5.25 VDC?
voltage and return circuit.
STEP 3A-2: Check for an active fault Fault Code 123 inactive?
code.
STEP 3B: Inspect engine control module Dirty or damaged pins?
and engine harness connector
pins.
STEP 3B-1: Check the engine control Fault Code 122 active and Fault
module response. Code 123 inactive?
STEP 3B-2: Check for an active fault Fault Code 123 inactive?
code.
STEP 4: Clear the fault code.
STEP 4A: Disable the fault code. Fault Code 123 inactive?
STEP 4B: Clear the inactive fault codes. All fault codes cleared?
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--- Page 8 ---
ISB, ISBe2, ISBe3, ISBe4, QSB4 [...]
Page TF-98 Section TF - Troubleshooting Fault Codes
STEP 2B: Check the accelerator pedal or lever position sensor supply voltage and return circuit.
Condition:
• Turn keyswitch OFF.
• Disconnect the accelerator pedal or lever position sensor from the OEM harness.
• Turn keyswitch ON.
Action Specification/Repair Next Step
Measure the voltage from the accelerator pedal 4.75 to 5.25 VDC? 2C
or lever position +5 VDC SUPPLY pin to the YES
accelerator pedal or lever position RETURN pin
at the sensor connector of the OEM harness.
4.75 to 5.25 VDC? 3A
Refer to the wiring diagram for connector pin
identification. NO
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--- Page 9 ---
ISB, ISBe2, ISBe3, ISBe4, QSB4 [...]
Page TF-130 Section TF - Troubleshooting Fault Codes
STEP 3B: Check for an inactive fault code.
Condition:
• Connect all components.
• Turn keyswitch ON.
• Connect INSITE™ electronic service tool.
Action Specification/Repair Next Step
Check for the appropriate circuit response after Fault Code 134 inactive? 4A
30 seconds. YES
• Use INSITE™ to read the fault codes.
Repair:
The removal and installation of the connector
corrected the fault.
Fault Code 134 inactive? 4A
NO
Repair:
Replace the ECM. Refer to Procedure
019-031 in Section 19.
STEP 4: Clear the fault codes.
STEP 4A: Disable the fault code.
Condition:
• Connect all components.
• Connect INSITE™ electronic service tool.
Action Specification/Repair Next Step
Disable the fault code. Fault Code 134 inactive? 4B
• Start the engine and let it idle for one minute. YES
• Use INSITE™ electronic service tool, verify
that the fault code is inactive.
Fault Code 134 inactive? 1A
NO
Repair:
Return to the troubleshooting steps or
contact a local Cummins® Authorized Repair
Location if all steps have been completed
and rechecked.
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--- Page 10 ---
ISB, ISBe2, ISBe3, ISBe4, QSB4 [...]
Page TF-162 Section TF - Troubleshooting Fault Codes
STEP 3B-1: Check the engine control module response.
Condition:
• Turn keyswitch OFF.
• Disconnect the engine harness from the ECM.
• Turn keyswitch ON.
• Connect INSITE™ electronic service tool.
Action Specification/Repair Next Step
Check the ECM response. Fault Code 135 active and Fault Code 141 3B-2
inactive?
Place a jumper wire between the oil pressure +5
volt SUPPLY pin and the oil pressure SIGNAL YES
pin at the engine control module engine
connector. Fault Code 135 active and Fault Code 141 4A
Refer to the wiring diagram for connector pin inactive?
identification. NO
Start and idle the engine for 1 minute with the oil Repair:
temperature higher than 49°C [120°F].
Replace the ECM. Refer to Procedure
• Use INSITE™ electronic service tool to read 019-031 in Section 19.
the fault codes.
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--- Page 11 ---
ISB, ISBe2, ISBe3, ISBe4, QSB4 [...]
Page TF-194 Section TF - Troubleshooting Fault Codes
FAULT CODE 144 (QSB Marine Application) - Engine Coolant Temperature 1
Sensor Circuit - Voltage Above Normal or Shorted to High Source
TROUBLESHOOTING SUMMARY
CAUTION
To reduce the possibility of damaging a new ECM, all other active fault codes must be investigated prior to
replacing the ECM.
CAUTION
To reduce the possibility of pin and harness damage, use the following test leads when taking a
measurement: Part Number 3822758 - Deutsch/AMP/Metri-Pack test lead and Part Number 3822917 - Deutsch/
AMP/Metri-Pack test lead.
STEPS SPECIFICATIONS SRT CODE
STEP 1: Check the fault codes.
STEP 1A: Check for an inactive fault code. Fault Code 144 inactive?
STEP 2: Check the engine coolant temperature sensor and circuit.
STEP 2A: Inspect the engine coolant Dirty or damaged pins?
temperature sensor and
connector pins.
STEP 2B: Check the sensor resistance. 180 ohms to 160k ohms?
STEP 2C: Check the fault codes and verify Fault Code 144 is active?
sensor condition.
STEP 3: Check the ECM and engine harness.
STEP 3A: Inspect the ECM and engine Dirty or damaged pins?
harness connector pins.
STEP 3B: Check the ECM response. Fault Code 145 active and Fault
Code 144 inactive?
STEP 3C: Check for an open circuit in the Less than 10 ohms?
engine harness.
STEP 3C-1: Check for an open circuit in Less than 10 ohms?
the engine harness.
STEP 3D: Check for a pin-to-pin short Greater than 100k ohms?
circuit in the engine harness.
STEP 3E: Check for an inactive fault code. Fault Code 144 inactive?
STEP 4: Clear the fault codes.
STEP 4A: Disable the fault code. Fault Code 144 inactive?
STEP 4B: Clear the inactive fault codes. All fault codes cleared?
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--- Page 12 ---
Engine Coolant Temperature - Data Valid but Above Norma [...] ISB, ISBe2, ISBe3, ISBe4, QSB4 [...]
Page TF-226 Section TF - Troubleshooting Fault Codes
Fault Code 146 (QSB Marine Application)
Engine Coolant Temperature - Data Valid but Above Normal Operational Range - Moderately
Severe Level
CODES REASON EFFECT
Fault Code: 146 Engine Coolant Temperature - Marine: calibration dependent.
PID(P), SID(S): P110 Data Valid but Above Normal
SPN: 110 Operational Range - Moderately
FMI: 0/16 Severe Level. Engine coolant
Lamp: Amber temperature signal indicates
SRT: engine coolant temperature is
above engine protection warning
limit.
Engine Coolant Temperature Sensor Circuit
Circuit Description:
The engine coolant temperature sensor is used by the Electronic Control Module (ECM) to monitor the engine coolant
temperature. The ECM monitors the voltage on the signal pin and converts this to a temperature value. The engine
coolant temperature value is used by the ECM for the engine protection system and engine emissions control.
Component Location:
The engine coolant temperature sensor is located on the exhaust side of the engine near the thermostat housing.
Refer to Procedure 100-002 for a detailed component location view.
Shop Talk:
This fault code indicates that coolant temperature has exceeded the engine protection limits for high coolant
temperature. Refer to Engine Coolant Temperature Above Normal symptom troubleshooting tree.
Refer to Troubleshooting Fault Code t05-146
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--- Page 13 ---
Intake Manifold Air Pressure/Temperature Sensor Circuit [...] ISB, ISBe2, ISBe3, ISBe4, QSB4 [...]
Page TF-258 Section TF - Troubleshooting Fault Codes
Original Wiring Harness - Intake Manifold Air Temperature Sensor Circuit
Revised Wiring Harness - Intake Manifold Air Temperature Sensor Circuit
Refer to Troubleshooting Fault Code t05-154.
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--- Page 14 ---
ISB, ISBe2, ISBe3, ISBe4, QSB4 [...]
Page TF-290 Section TF - Troubleshooting Fault Codes
TROUBLESHOOTING STEP
STEP 1: Check the fault codes.
STEP 1A: Check for an active fault code.
Condition:
• Turn keyswitch ON.
• Connect INSITE™ electronic service tool.
Action Specification/Repair Next Step
Check for an active fault code. Fault Code 195 active? 2A
• Use INSITE™ electronic service tool to read YES
the fault codes.
Fault Code 195 active? Use the
NO following
procedure for
an inactive or
intermittent
fault code.
Refer to
Procedure
019-362 in
Section 19.
STEP 2: Check the engine coolant level sensor and circuit.
STEP 2A: Inspect the engine coolant level sensor and connector pins.
Condition:
• Turn keyswitch OFF.
• Disconnect the OEM harness from the ECM.
Action Specification/Repair Next Step
Inspect the OEM harness and engine coolant Dirty or damaged pins? 4A
level sensor connector pins for the following: YES
• Loose connector
• Corroded pins Repair:
• Bent or broken pins A damaged connection has been detected in
• Pushed back or expanded pins the ECM connector or OEM harness
• Moisture in or on the connector connector.
• Missing or damaged connector seals
• Dirt or debris in or on the connector pins Clean the connector and pins.
• Wire insulation damage Repair the damaged harness, connector, or
• Connector shell broken pins if possible. Refer to Procedure 019-071
• Damaged locking tab connector. in Section 19.
Use the following procedure for general
inspection techniques. Refer to Procedure Dirty or damaged pins? 2B
019-361 in Section 19. NO
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--- Page 15 ---
ISB, ISBe2, ISBe3, ISBe4, QSB4 [...]
Page TF-322 Section TF - Troubleshooting Fault Codes
TROUBLESHOOTING STEP
STEP 1: Check the fault codes.
STEP 1A: Check for sensor supply fault codes.
Condition:
• Turn keyswitch ON.
• Connect INSITE™ electronic service tool.
Action Specification/Repair Next Step
Check for sensor supply fault codes. Fault Code 352 active? Refer to
• Use INSITE™ electronic service tool to read YES Fault Code
the fault codes. 352
Fault Code 352 active? 1B
NO
STEP 1B: Check for an inactive fault code.
Condition:
• Turn keyswitch ON.
• Connect INSITE™ electronic service tool.
Action Specification/Repair Next Step
Check for an inactive fault code. Fault Code 196 inactive? Use the
• Use INSITE™ electronic service tool to read YES following
the fault codes. procedure for
an inactive or
intermittent
fault code.
Refer to
Procedure
019-362 in
Section 19.
Fault Code 196 inactive? 2A
NO
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--- Page 16 ---
ISB, ISBe2, ISBe3, ISBe4, QSB4 [...]
Page TF-354 Section TF - Troubleshooting Fault Codes
STEP 2D: Check the fault codes and verify sensor condition.
Condition:
• Turn keyswitch OFF.
• Connect the barometric pressure sensor to the engine harness.
• Turn keyswitch ON.
• Connect INSITE™ electronic service tool.
Action Specification/Repair Next Step
Check the appropriate circuit response after 30 Fault Code 222 active? 4A
seconds. YES
• Use INSITE™ electronic service tool to read
the fault codes. Repair:
A damaged sensor has been detected.
Replace the barometric pressure sensor.
Refer to Procedure 019-004 in Section 19.
Fault Code 222 active? 4A
NO
Repair:
None. The removal and installation of the
connector corrected the fault.
STEP 3: Check the engine control module and engine harness.
STEP 3A: Inspect engine control module and engine harness connector pins.
Condition:
• Turn keyswitch OFF.
• Disconnect the engine harness from the ECM.
Action Specification/Repair Next Step
Inspect the engine harness and engine control Dirty or damaged pins? 4A
module engine connector pins for the following: YES
• Loose connector
• Corroded pins Repair:
• Bent or broken pins A damaged connection has been detected in
• Pushed back or expanded pins the engine control module engine connector
• Moisture in or on the connector or engine harness connector.
• Missing or damaged connector seals
• Dirt or debris in or on the connector pins Clean the connector and pins.
• Wire insulation damage Repair the damaged harness, connector or
• Connector shell broken. pins, if possible. Refer to Procedure 019-043
Use the following procedure for general in Section 19.
inspection techniques. Refer to Procedure
019-361 in Section 19. Dirty or damaged pins? 3A-1
NO
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--- Page 17 ---
External Speed Command Input (Multiple Unit Synchronica [...] ISB, ISBe2, ISBe3, ISBe4, QSB4 [...]
Page TF-386 Section TF - Troubleshooting Fault Codes
Multi-Unit Number 3 Multi-Unit Number 2 Multi-Unit Number 1 Description
Inactive Active Active Secondary 2
Active Inactive Inactive Secondary 3
Active Inactive Active Secondary 4
Active Active Inactive Secondary 5
Active Active Active Error Condition
Refer to Troubleshooting Fault Code t05-237
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--- Page 18 ---
ISB, ISBe2, ISBe3, ISBe4, QSB4 [...]
Page TF-418 Section TF - Troubleshooting Fault Codes
STEP 4: Clear the fault codes.
STEP 4A: Disable the fault code.
Condition:
• Connect all components.
• Turn keyswitch ON.
• Engine not running.
• Vehicle not moving.
Action Specification/Repair Next Step
Disable the fault code. Fault Code 242 inactive? 4B
• With the keyswitch ON and the vehicle YES
stationary, wait 1 minute.
• Use INSITE™ electronic service tool, verify
that Fault Code 242 is inactive. Fault Code 242 inactive? 1A
NO
Repair:
Return to the troubleshooting steps or
contact your local Cummins® Authorized
Repair Location or OEM dealer if all the
steps have been completed and checked
again.
STEP 4B: Clear the inactive fault codes.
Condition:
• Connect all components.
• Turn keyswitch ON.
• Connect INSITE™ electronic service tool.
Action Specification/Repair Next Step
Clear the inactive fault codes. All fault codes cleared? Repair
• Use INSITE™ electronic service tool to erase YES complete
the inactive fault codes.
All fault codes cleared? Appropriate
NO troubleshooti
ng steps
Repair:
Troubleshoot any remaining fault codes.
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--- Page 19 ---
ISB, ISBe2, ISBe3, ISBe4, QSB4 [...]
Page TF-450 Section TF - Troubleshooting Fault Codes
TROUBLESHOOTING STEP
STEP 1: Check the fault codes.
STEP 1A: Check for an active fault code.
Condition:
• Turn keyswitch ON.
• Connect INSITE™ electronic service tool.
Action Specification/Repair Next Step
Check for an active fault code. Fault Code 271 active? 2A
• Use INSITE™ electronic service tool to read YES
the fault codes.
Fault Code 271 active? Inactive or
NO Intermittent
Fault Code,
Refer to
Procedure