Ram Truck 1500, 2500 & 3500 (2006-2008)

Electronic Control Module

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Operation



5.9L & 6.7L Engines

The main function of the Engine Control Module (ECM) is to electrically control the fuel system. The ECM also controls certain transmission and other functions previously controlled by the Powertrain Control Module (PCM).

The ECM can adapt its programming to meet changing operating conditions.

The ECM receives input signals from various switches and sensors. Based on these inputs, the ECM regulates various engine and vehicle operations through different system components. These components are referred to as ECM outputs. The sensors and switches that provide inputs to the ECM are considered ECM inputs.

ECM inputs are as follows:



Accelerator Pedal Position Sensor (APPS) Signals #1 and #2
 
AC system pressure
 
Auto shutdown (ASD) sense
 
Battery temperature
 
Battery temperature sensor
 
Battery voltage
 
Brake switch
 
Camshaft Position Sensor (CMP)
 
Crankshaft Position Sensor (CKP)
 
Data link connection for a scan tool
 
Engine Coolant Temperature (ECT) sensor
 
EATX module (if equipped)
 
Fuel level
 
Fuel pressure sensor
 
Fan speed (engine cooling fan)
 
Generator (battery voltage) output
 
Governor pressure (Auto. trans.)
 
Ground circuits
 
Inlet air temperature sensor/pressure sensor
 
Intake air temperature sensor/MAP sensor
 
CAN C BUS (+) circuits
 
CAN C BUS (-) circuits
 
Key switch (ignition)
 
Oil Pressure switch
 
Overdrive switch (automatic transmission only)
 
Park/neutral switch (auto. trans. only)
 
Power ground
 
SCI data link bus (+) circuits
 
SCI data link bus (-) circuits
 
Sensor return
 
Signal ground
 
Speed control multiplexed single wire input
 
Transfer case switch (4WD range position)
 
Transmission governor psi (automatic transmission only)
 
Transmission OSS (automatic transmission only)
 
Transmission oil pressure (automatic transmission only)
 
Transmission oil temperature (automatic transmission only)
 
Transmission throttle valve position (automatic transmission only)
 
Vehicle speed signal
 
Water-In-Fuel (WIF) sensor
 

ECM outputs are as follows:



A/C clutch relay
 
Auto shutdown (ASD) relay
 
Data link connection for diagnostic scan tool
 
Fan clutch PWM
 
Five volt sensor supply (primary)
 
Five volt sensor supply (secondary)
 
Fuel control actuator
 
Fuel injector driver circuits
 
Fuel transfer (lift) pump
 
Generator field driver (-)
 
Generator field driver (+)
 
Governor pressure (VFS solenoid)
 
Intake manifold air heater relays #1 and #2 control circuits
 
CAN C BUS (+/-) circuits for: speedometer, voltmeter, fuel gauge, oil pressure gauge/lamp, engine temp. gauge and speed control warn. lamp
 
Malfunction indicator lamp (Check engine lamp). Driven through J1850 circuits.
 
Oil pressure switch/warning lamp (data bus)
 
Overdrive/3-4 shift solenoid (automatic transmission only)
 
SC source
 
SCI data link bus (+) circuits
 
SCI data link bus (-) circuits
 
Speed control vacuum solenoid
 
Speed control vent solenoid
 
Tachometer (if equipped). Driven through J1850 circuits.
 
TCC solenoid (automatic transmission only)
 
Transmission battery relay (automatic transmission only)
 
Transmission throttle valve actuator (automatic transmission only)
 
Transmission governor solenoid (automatic transmission only)
 
Wait-to-start warning lamp (data bus)
 
Turbo wastegate solenoid
 
Water-In-Fuel (WIF) warning lamp (data bus)
 

Removal & Installation



5.9L & 6.7L Engines
  1. Record any Diagnostic Trouble Codes (DTC's) found in the Engine Control Module (ECM).
    WARNING
    To avoid possible voltage spike damage to the ECM, ignition key must be off, and both negative battery cables must be disconnected before unplugging ECM connectors.

  2.  
  3. Disconnect both negative battery cables at both batteries.
    NOTE
    Access to the ECM is easier by working through the left front wheel opening.

  4.  
  5. Remove left front wheel.
  6.  
  7. Remove plastic left front fender splash shield. Refer to Slash Shield Front Wheel Hose in Body section.
  8.  
  9. Remove electrical connector bolts at ECM. As each bolt is being removed, very carefully remove connectors from the ECM.
  10.  
  11. Remove three ECM mounting bolts (6) and remove ECM from engine.
  12.  

To install:

  1. Position ECM (5) to the ECM support bracket and install mounting bolts. Tighten bolts to 18 ft. lbs. (24 Nm).
  2.  
  3. Check pins in electrical connectors for corrosion, damage or dirt intrusion. Also check all pins for being bent. Repair as necessary. Damaged, dirty, bent or corroded pins could result in poor conductivity, causing intermittent electrical issues or DTC's.
  4.  
  5. Clean pins in electrical connectors with an electrical contact cleaner.
  6.  
  7. Install the connectors to ECM. Tighten connector bolts to 27 in. lbs. (3 Nm).
  8.  
  9. Install the splash shield.
  10.  
  11. Install left front wheel.
  12.  
  13. Connect both negative battery cables.
  14.  
  15. Use a diagnostic scan tool to erase any (DTC's) from ECM.
  16.  

Testing



5.9L & 6.7L Engines
  1. Turn the ignition off.
  2.  
  3. Disconnect the ECM harness connectors.
  4.  
  5. Using a 12-volt test light connected to 12-volts, check each of the ECM ground circuits in ECM harness connector.
  6.  
  7. If the test light illuminates for each cavity ECM Ground circuits are okay, if not repair open circuit.
  8.  
  9. Turn the ignition on to check fused ignition switch output.
  10.  
  11. Using a 12-volt test light connected to ground, check the fused ignition switch output circuit in ECM harness connector.
  12.  
  13. If the test light illuminates the fused ignition switch output circuit is okay, if not repair open circuit.
  14.  
  15. Turn the ignition off.
  16.  
  17. Using a 12-volt test light connected to ground, check each fused B+ circuit in the ECM harness connector.
  18.  
  19. If the test light illuminates brightly for each circuit, fused B+ circuit is okay. If not repair fused B+ circuit. The power and ground test is complete. Suspect faulty ECM
  20.  

 
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