CM2670 Control System
ECM Architecture | Sensors | Actuators | J1939 | Fault Codes | INSITE
Complete electronic control system teaching guide for the CM2670 ECM. Covers all engine and aftertreatment sensors, switches, output devices, J1939 data communication, fault code classification, and INSITE diagnostic capabilities.
01 — CM2670 ECM ARCHITECTURE
ECM Hardware
- Model: CM2670D
- Mount: Left side of engine block
- J1 connector: 96-pin (engine)
- J2 connector: 96-pin (OEM)
- Harness: Delphi plugs
- Test lead PN: 5299368
- Connector tool PN: 2892512
Power Supply
- 3-way power architecture:
- 1. Uninterruptible (direct battery)
- 2. Key switch (ignition)
- 3. Ground
- After key-off: maintain battery
- power 10+ min for data storage
- and DEF valve cooling
Software
- Requires INSITE v8.5+
- NS VI telecommunications support
- INLINE adapter required
- J1587/J1708 or J1939 interface
- Accelerator pedal types:
- Potentiometer (2-3 kOhm)
- Hall-effect (dual 0.25-4.75V)
CM2670 ECM — INPUT / OUTPUT ARCHITECTURE
02 — ENGINE SENSORS
| SENSOR | TYPE | LOCATION | SIGNAL | NOTE |
|---|---|---|---|---|
| Crankshaft Speed/Position | Hall-effect | Front gear housing | 60-2 tooth wheel | Primary timing reference |
| Camshaft Speed/Position | Hall-effect | Front cylinder head | 6+1 tooth wheel | Cylinder identification |
| Intake Manifold P/T (TMAP) | Combined P+T | Air inlet manifold | 0.25-4.75 VDC | Boost pressure + charge air temp |
| Oil Pressure | Analog | Left side near ECM | 0.25-4.75 VDC | Engine protection input |
| Oil Temperature | Thermistor | Left side near ECM | NTC resistance | Oil condition monitoring |
| Exhaust Pressure | Analog | Between cyl #4-#5 | Integral signal pipe | Back-pressure monitoring |
| Rail Pressure | Integrated | On HP common rail | 0.25-4.75 VDC | Non-replaceable separately |
| Coolant Temperature | Thermistor | Thermostat housing | NTC resistance | Thermal management |
| Turbo Compressor Inlet P/T | Combined P+T | After air filter (OEM) | 0.25-4.75 VDC | Air filter restriction |
| Coolant Level | Active/Passive | OEM supplied | 3-wire or 2-wire | Low coolant protection |
| Water in Oil (WIF) | Probe | OEM supplied | 5V ref, ground on detect | Contamination alert |
| Ambient Temperature | Thermistor | OEM supplied | NTC resistance | Cold start strategy |
Sensor Signal Diagnostics
NORMAL RANGE
0.25 - 4.75 V
Standard analog sensor range
ABOVE RANGE
> 4.75 V
Open circuit / short to power
BELOW RANGE
< 0.25 V
Short to ground
STATE CHANGE DIAGNOSTIC METHOD:
Jumper signal wire to return wire → should trigger "below range" fault. Connect 5V to signal wire → should trigger "above range" fault. If faults don't appear → ECM or wiring issue.
03 — AFTERTREATMENT SENSORS
DOC Inlet Temperature
Thermistor
DOC efficiency monitoring
DPF Inlet Temperature
Thermistor
DOC exotherm confirmation
DPF Outlet Temperature
Thermistor
Regen temperature control
SCR Inlet Temperature
Thermistor
Dosing enable threshold (> 200 C)
SCR Outlet Temperature
Thermistor
SCR efficiency monitoring
Engine Outlet NOx
Smart (J1939)
Upstream NOx measurement
SCR Outlet NOx
Smart (J1939)
DeNOx efficiency calculation
DPF Differential Pressure
Analog
Soot load estimation
DEF Tank Temp/Level/Density
Smart (J1939)
DEF quality and quantity
DEF Injection Valve Pressure
Integrated
Dosing pressure control
04 — SWITCHES (20+)
Cruise Control
- Set
- Resume
- Accel
- Decel
- On/Off
Engine Control
- Remote PTO
- Engine Protection Override
- Engine Brake Sel 1
- Engine Brake Sel 2
- EBP Selector (knob)
DPF/Regen
- DPF Regen Switch
- Diagnostic Test Mode
- DPF Regen Inhibit
Remote/Throttle
- Remote Start R0
- Remote Start R1
- Remote Throttle Enable
- Throttle Interlock
Vehicle
- Parking Brake
- Clutch Pedal
- Service Brake
- A/C Pressure
- Manual Fan Control
Configuration
- Max Operating Speed
- Rear Axle Ratio
05 — OUTPUT DEVICES
Dashboard Indicators
MIL
Malfunction Indicator Lamp (yellow)
HEST
High Exhaust System Temperature
DPF
DPF status indicator
DWS
Diesel Water Separator
RED STOP
Engine shutdown required
YELLOW ALARM
Warning — derate possible
WAIT-TO-START
Grid heater active
Relays
Solenoids & Actuators
06 — SAE J1939 DATA COMMUNICATION
Public Links (J2 OEM Connector)
LINK 1 — Vehicle Interaction
250/500 kbps | Transmission, ABS, instrument cluster
LINK 2 — Cab Diagnostic
250/500 kbps | INSITE connection via INLINE adapter
Private Links (J1 Engine Connector)
LINK 3 — Engine Diagnostic
250/500 kbps | Engine-side sensor communication
LINK 4 — ATS Smart Components
250/500 kbps | NOx sensors, DEF tank sensor (smart)
120 Ohm termination resistors required at each end of every J1939 bus. Missing termination causes communication errors and erratic fault codes.
07 — FAULT CODE CLASSIFICATION
Circuit Faults
- Voltage above normal (> 4.75V)
- Voltage below normal (< 0.25V)
- Current above normal
- Current below normal
Mechanical Faults
- Not responding properly
- Out of calibration
Logic / Rationality Faults
- Drift high
- Drift low
- Erratic / intermittent data
- Condition exists
Communication Faults
- Received network error
- Abnormal update rate
- Smart device damage
Fault Code Format
CUMMINS FORMAT
3-4 digit Cummins fault code
Example: 111 = ECM hardware failure
SAE FORMAT
SPN (Suspect Parameter Number) / FMI (Failure Mode Identifier)
Example: SPN 629 / FMI 12 = ECM internal
08 — INSITE DIAGNOSTIC TESTS
Engine Tests
- 01Double fan clutch test
- 02Intake air heater override
- 03Starter motor locking relay override
- 04Fan override
- 05SAE J1939 communication interface control
- 06Switch and sensor intermittent connection test
- 07Fuel system diagnostic — cylinder cut-off
- 08Fuel system diagnostic — fuel pump actuator override
- 09Fuel system diagnostic — injector performance
- 10Dynamometer settings
- 11Engine state monitoring
Aftertreatment Tests
- 01DEF injection pump override
- 02DEF injection system heating test
- 03DEF injection system leak test
- 04SCR system performance test (SPT 2.0)
- 05DPF restriction test
- 06DPF regeneration (service regen)