Series 50G/60G Troubleshooting – Section 7.2 Electronic System

Section 7.2
Electronic System

This section describes the function and installation requirements for the electronic system of DDC Series 50G/60G Engine. A simple installation may require a basic understanding of electrical circuits while a more comprehensive electrical or electronics background is required to access all the capabilities of Detroit Diesel Electronic Controls (DDEC®). ‪

The DDEC IV system is similar to the diesel engine controls in function and appearance. The system optimizes control of engine functions which affect fuel economy, driveability, and emissions. DDEC IV provides the capability to protect the engine from serious damage resulting from conditions such as high engine temperatures, low oil pressure, combustion knock, etc. It is capable of the same vehicle interface controls as the diesel engine such as door interlock, high and low idle, cruise control, etc. Engine and vehicle management options such as ProDriver are also available. OEM-supplied hardware and DDC-supplied hardware are required to install DDEC IV. ‪

The Electronic Control Module (ECM) receives electronic inputs from sensors on the engine and vehicle and uses the information to control engine operation. It controls spark ignition and throttle plate position based upon predetermined calibration tables in its memory. Portable equipment facilitates access to DDEC IV diagnostic capabilities. The Diagnostic Data Reader (DDR) requests and receives engine data and diagnostic codes. This equipment provides many unique capabilities including parameter versus engine speed (or time), printer output, and data snapshot. The DDR also provides limited programming capability. DDEC IV provides three industry standard serial data links: SAE Standards J1587, J1922, and J1939. SAE standard J1587 provides two-way communications for the diagnostic equipment and vehicle displays. SAE standards J1922 and J1939 provide control data to other vehicle systems such as transmissions and traction control devices.‪

Section 7.2.1
OEM-Supplied Hardware Requirements

The minimum OEM-supplied hardware required is listed in Table "Minimum OEM-Supplied Hardware" . Refer to DDEC IV Application and Installation , 7SA742 for additional information.‪

Hardware‪	Description‪
Vehicle Interface Harness Assembly (VIH)‪	Connects the vehicle functions to the ECM.‪
ECM Power Harness Assembly‪	Connects battery power (12/24 V) and ground to the ECM and includes fuse(s) or circuit breaker(s).‪
Coil Power Harness‪	Provides power to the engine ignition coils.‪
OEM Sensor Power Harness Assembly‪	Provides power (12 V only) to the Pulse Width Modulated Stepper Motor Valve (PSV), Signal Noise Enhancement Filter (SNEF) module, throttle and oxygen sensor interface module. This harness connects to a pigtail on the Engine Sensor Harness (ESH).‪
Fuel Shutoff Harness‪	Connects to the engine-side fuel shutoff solenoid and provides power to the fuel shutoff valve. (DDEC switch, 12/24 V).‪
OEM Sensor Ground Harness Assembly‪	Provides ground to the PSV, throttle and Oxygen Sensor Interface Module. This harness connects to a pigtail on the ESH.‪
Ignition Switch‪	Controls 12/24 V ignition source.‪
Check Engine Light (CEL)‪	Mounted in instrument panel. Indicates required maintenance. Light is yellow.‪
Stop Engine Light (SEL)‪	Mounted in instrument panel. Indicates engine shutdown condition. Light is red.‪
Coolant Level Sensor (CLS)‪	Mounts in radiator top tank or remote surge tank.‪

Section 7.2.2
DDC-Supplied Hardware Requirements

The minimum DDC-supplied hardware required is listed in Table "Minimum DDC-Supplied Hardware" . Refer to DDEC IV Application and Installation , 7SA742 for additional information.‪

Hardware‪	Description‪
Engine Sensor Harness‪	Facilitates the receipt of input and output signals, controlling the fuel injection process and engine speed.‪
Oxygen Sensor Harness‪	Connects the oxygen sensor to the interface module. It is a ship loose item (Gas only).‪
Oxygen Sensor‪	Provides a signal proportional to air/fuel ratio. This is a ship loose item.‪
Exhaust Temperature Sensor‪	Warns against malfunction that causes excessive exhaust temperature. This is a ship loose item (Gas only).‪

Section 7.2.3
INSTALLATION REQUIREMENTS

The Series 50G/60G DDEC installation requirements are the same as those published in the DDEC IV Application and Installation manual except for the specifics shown in this manual. Refer to DDEC IV Application and Installation , 7SA742 for additional information.‪

Section 7.2.3.1
Dedicated Power and Ground Requirements

The wires listed in Table "Wires Requiring Dedicated Power and Ground" require dedicated power and grounds. ‪

Wire Number‪	Description‪
956‪	Throttle Ground‪
443‪	SNEF Power (Ignition Switched)‪
150‪	PSV Ground‪
446‪	PSV Power (Ignition Switched)‪
957‪	Oxygen Sensor Interface Module Ground‪
444‪	Oxygen Sensor Interface Power (Ignition Switched)‪
445‪	Throttle Power (Ignition Switched and DDEC Switched)‪

Section 7.2.3.2
Relay Powered Throttle

Throttle power actuation will be done through an OEM-supplied relay using either 12 or 24 V. Wire 561 (High-Side Digital Output), will provide ECM power (12 or 24 V) to trigger the relay. A dedicated 12 or 24 V power source will travel through the relay to wire 445 to the throttle. Wires 561 and 445 are show on the main wiring diagram layout and their individual connector diagram layouts (see Figure "OEM Sensor Power Harness" ). ‪

Figure 1. OEM Sensor Power Harness

Section 7.2.3.3
Relay Powered Fuel Shutoff Valves

Electronically-controlled fuel shutoff solenoid valves are required on the high pressure side of the fuel system (typically at the fuel tanks) and the low pressure side of the fuel system near the engine. The OEM is responsible for the high pressure shutoff valves. DDC will provide the engine-side solenoid valve (12 or 24 V valves are available). All electronic fuel shutoff solenoid valves must be DDEC controlled. ‪

DDEC control of the fuel shutoff solenoid valves will be done through an OEM-supplied relay using either 12 or 24 V. Wire 562 (High-Side Digital Output) will provide ECM power, either 12 or 24 V, to trigger the relay. A dedicated 12 or 24 V power source will travel from the relay to the solenoid valves (see Figure "Fuel Shutoff Harness" ). The tank-side solenoids and the engine-side solenoid must be controlled in this manner. Separate relays can be used for the tank-side solenoids and the engine-side solenoid, as long as they are triggered by wire 562. ‪

Figure 2. Fuel Shutoff Harness

Section 7.2.4
ELECTRONIC CONTROL MODULE

The Series 50G/60G Engine is a spark-ignited natural gas fueled engine that uses the DDEC system. The engine-mounted ECM includes control logic to provide overall engine management. See Figure "Electronic Control Module" .‪

Figure 3. Electronic Control Module

The ECM continuously performs self diagnostic checks and monitors other electrical system components. System diagnostic checks are made when the ignition is enabled and continue throughout all engine operating modes.‪

NOTICE:
A diesel ECM and a natural gas ECM cannot be interchanged. An ECM is programmed for either diesel fuel with diesel calibration or natural gas with gas calibration. To interchange the two types of ECM's could cause engine damage.‪

The ECM hardware for the Series 50G/60G engine is unique.‪

Section 7.2.5
Ignition System

The Series 50G/60G engine uses an Integrated Coil and Electronics (ICE) direct ignition system that includes a coil for each cylinder pair and an ignition module within each encapsulated assembly. During engine operation, the DDEC ECM sends trigger signals to the ICE modules, which direct high current pulses through the coils resulting in secondary voltages of 30,000 to 50,000 volts traveling through the ignition boots to the spark plugs. The ICE system provides high voltage directly to each spark plug electrically, not mechanically, as does a distributor.‪

NOTICE:

The Series 50G/60G spark ignition system can generate voltages as high as 50,000 V. High voltage fast pulses from the coil can create broad band noise, Radio Frequency Interference (RFI), and Electromagnetic Interference (EMI). RFI/EFI can disrupt vehicle electrical/electronic systems with varying degrees of severity. Use the guidelines in this publication to keep the ignition RFI/EMI down to acceptable levels.‪

Criteria for the Ignition System: ‪

• Ground straps are essential for conductive connections between individual metal parts in the vehicle.
• The Series 50G/60G Engine Ignition System requires a 12 V supply to the ignition coils which must be sourced directly from the battery or equivalent bus bar.

Use the following guidelines when installing a Series 50G/60G engine in a vehicle:‪

1. Make sure the following points are ground strapped together: Body to chassis, chassis to starter ground, and starter ground to engine block.

   Note: This practice ensures that none of the vehicle’s metal parts are at different voltage potentials.

2. Route all electrical wiring at a maximum distance away from ignition coils, ignition wires, and spark plugs.
3. Replace any ignition components that show signs of deterioration and check the plugs, plug wires, and coil resistances to see if they are within specifications. Refer to Series 60 Service Manual , 6SE483, or Series 50 Service Manual , 6SE50, for ignition system specifications.

   Note: Suspect or marginal ignition components can generate high levels of RFI/EMI.

Section 7.2.5.1
Engine Protection

The Series 50G/60G engine protection system is similar to the DDEC diesel engine protection system, with the addition of natural gas engine specific protection. Just like the diesel ECM, the natural gas ECM monitors all engine sensors and electronic components, and recognizes system malfunctions. If a critical fault is detected, the CEL and SEL illuminate and a malfunction code is logged into the ECM’s memory.‪

The additional Series 50G/60G protection types are as follows:‪

• High intake manifold pressure
• High intake manifold air temperature
• High engine knock level
• High exhaust temperature
• Throttle actuator fault protection
• DDEC sensor supply voltage fault protection

  Note: All other engine protection functions are identical to diesel including engine override and logging of fault codes.

Section 7.2.5.2
Engine Critical Fault

In the event that an engine critical fault has been detected, the following sequence will occur:‪

1. The CEL illuminates.
2. The SEL illuminates if any condition exceeds its safe operating level.
3. The throttle actuator ramps down engine power.
4. The vehicle gas supply shutoff solenoid is set to OFF.
5. PSV closes.
6. The ignition system shuts down.

Section 7.2.5.3
Application Code System

The Detroit Diesel Application Code System (ACS) was initiated along with the introduction of DDEC III. The application code system includes all application-related DDEC parameters. The Application Engineering department has developed the list of parameters and default parameters that are selected by Product Distribution for each application group. New 6N4C application codes are required for the Series 50G/60G engine due to the differing application requirements versus the standard diesel. For example, the Series 50G/60G engine requires the use of a DDEC-controlled fuel solenoid shutoff valve. There is no option for fuel shutoff available on the standard diesel controls.‪

Section 7.2.6
Pulse Width Modulated Stepper Motor Valve

The PSV is used to bias gas flow to the venturi mixer as a means of Air/Fuel (A/F) ratio control (see Figure "Pulse Width Modulated Stepper Motor Valve and Fuel Mixer Assembly" ). The PSV is electrically connected to the ECM and 12 V battery power through an 8-pin connector that mates to the ESH. The PSV supplies a gas valve position analog signal to DDEC which can be monitored using the DDR. The signal indicates valve opening position. A diagnostic signal is supplied to DDEC for loss of command signal, piston obstruction or valve electronics failure.‪

1. PSV‪	5. Fuel Mixer‪
2. Bolt‪	6. O-rings‪
3. Washer‪	7. Fuel Transfer Tube‪
4. PSV O-ring‪	‪

Figure 4. Pulse Width Modulated Stepper Motor Valve and Fuel Mixer Assembly

Section 7.2.7
Sensors

The standard sensors for the Series 50G/60G engine are listed in Table "Standard Sensors for Series 50G/60G Engine" .‪

Low Pressure Fuel System (Generator Set)‪	High Pressure Fuel System (Bus and Coach)‪
Oil Temperature Sensor (OTS)‪	Exhaust Temperature Sensor‪
Oil Pressure Sensor (OPS)‪	Oil Pressure Sensor‪
Coolant Temperature Sensor (CTS)‪	Coolant Temperature Sensor‪
Coolant Level Sensor (CLS)‪	Coolant Level Sensor‪
Manifold Air Pressure Sensor (MAP)‪	Manifold Air Pressure Sensor‪
Timing Reference Sensor (TRS)‪	Timing Reference Sensor‪
Synchronous Reference Sensor (SRS)‪	Synchronous Reference Sensor‪
Fuel Temperature Sensor (FTS)‪	Fuel Temperature Sensor‪
Air Temperature Sensor (ATS)‪	Air Temperature Sensor‪
Throttle Position Sensor (TPS)‪	Throttle Position Sensor‪
Knock Sensor‪	Knock Sensor‪
PSV Position Sensor‪	PSV Position Sensor‪
—‪	Oxygen Sensor‪
—‪	Barometric Air Pressure Sensor (BAP)‪
—‪	Fuel Pressure Sensor (FPS)‪

Section 7.2.7.1
Knock Sensor and Signal Noise Enhancement Filter Module

Detroit Diesel has incorporated a combustion knock protection system using a Piezo-electric Knock Sensor and a SNEF module. The system provides a signal to DDEC indicating engine knock. In the event that combustion knock occurs, DDEC will modify ignition timing. If combustion knock continues after ignition timing has been modified, DDEC will begin to lean out the A/F mixture and reduce engine power until combustion knock is eliminated. ‪

The SNEF module is engine-mounted and grounded to the engine block via a ring terminal. Power is supplied through the OEM Sensor Power Harness. Power must be 12 VDC only and must be sourced directly from battery or equivalent bus bar.‪

Section 7.2.7.2
Fuel Temperature Sensor

The FTS sends an electrical signal to the ECM indicating fuel inlet temperature. The ECM uses this information to calculate fuel consumption.‪

On Series 50G/60G engines with the Compressed Natural Gas (CNG) high pressure fuel system the FTS is located in the PSV (see Figure "High Pressure Fuel System and Sensor Location for Engine Models 6067–TKG8 and 6047–TKG8" for Models 6067–TKG8 and 6047–TKG8 and Figure "High Pressure Fuel System and Sensor Location for Engine Model 6047–MKG8" for Model 6047–MKG8).‪

1. Fuel Temperature Sensor‪	6. Air Temperature Sensor‪
2. PSV‪	7. Low Pressure Regulator‪
3. Fuel Mixer‪	8. Fuel Pressure Sensor‪
4. Throttle‪	9. Fuel Inlet Tee Fitting‪
5. Inlet Elbow‪	‪

Figure 5. High Pressure Fuel System and Sensor Location for Engine Models 6067–TKG8 and 6047–TKG8

1. Low Pressure Regulator‪	5. Throttle‪
2. Fuel Temperature Sensor‪	6. Intake Tube Adaptor‪
3. PSV‪	7. Fuel Pressure Sensor‪
4. Fuel Mixer‪	8. Fuel Inlet Tee‪

Figure 6. High Pressure Fuel System and Sensor Location for Engine Model 6047–MKG8

Section 7.2.7.3
Exhaust Temperature Sensor

Excessive exhaust temperature may indicate a concern with the fuel system, the ignition system, or a mechanical fault. An exhaust temperature sensor will provide early warning and prevent damage. It must be mounted in the exhaust system within 305 mm (12 in.) of the turbine outlet (see Figure "High Pressure Fuel System and Sensor Location for Engine Models 6067–TKG8 and 6047–TKG8" ). The exhaust temperature sensor does not require any sealant or antiseize compound. The sensor pigtail must be connected to the ESH at the rear of the engine. The wires must be routed away from the exhaust system and kept out of contact with moving components. Refer to "7.2.8.8 Engine Sensor Harness" for a schematic of the ESH.‪

Section 7.2.7.4
Oxygen Sensor

Air/fuel ratio is a fundamental parameter for a natural gas engine. Precise control of the air/fuel ratio allows the engine to operate closer to the lean limit. As a result, exhaust emissions, fuel consumption, and exhaust temperatures are reduced. ‪

The oxygen sensor measures exhaust oxygen which is an indication of the air/fuel ratio (see Figure "Oxygen Sensor" ). If fuel system hardware, fuel quality, or engine operating conditions change, DDEC will sense this and make corrections to keep the air/fuel ratio on target. This is called “closed loop” control.‪

Figure 7. Oxygen Sensor

The oxygen sensor must be installed in the exhaust pipe within 305 mm (12 in.) of the turbine outlet. The sensor has pre-applied antiseize compound on the threads. The oxygen sensor harness must be used to connect the sensor to the oxygen sensor interface module located at the rear of the engine (see Figure "Oxygen Sensor Interface Module" ). The wires must be routed away from the exhaust system and kept out of contact with moving parts.‪

Figure 8. Oxygen Sensor Interface Module

Section 7.2.8
Wiring Harnesses

The DDEC system requires several wiring harnesses for proper operation.‪

Section 7.2.8.1
OEM Sensor Power Harness

This harness provides power to the SNEF module, PSV, throttle, and Oxygen Sensor Interface Module through a 4-pin connector. See Figure "OEM Sensor Power Harness" .‪

NOTICE:
The power supply for the SNEF module, PSV, throttle, and Oxygen Sensor Interface Module must be 12 VDC to ensure proper operation and to prevent engine damage.‪

Figure 9. OEM Sensor Power Harness

Section 7.2.8.2
Fuel Shutoff Harness

This harness connects to the engine-side fuel shutoff solenoid and provides power to the fuel shutoff valve (DDEC switch, 12/24 V). See Figure "Fuel Shutoff Harness" .‪

Figure 10. Fuel Shutoff Harness

Section 7.2.8.3
OEM Sensor Ground Harness

The OEM Sensor Ground Harness provides ground to the PSV, throttle, and Oxygen Sensor Interface Module. This harness connects to a pigtail on the ESH. See Figure "OEM Sensor Ground Harness" .‪

Figure 11. OEM Sensor Ground Harness

Section 7.2.8.4
Coil Power Harness

This harness provides power to the engine ignition coils. See Figure "Coil Power Harness " .‪

NOTICE:
The ignition coil power supply must be 12 VDC to ensure proper operation and to prevent engine damage.‪

Figure 12. Coil Power Harness

Section 7.2.8.5
Power Harness — Dual Fuse Installation

DDC recommends a dual fuse installation. This configuration will provide redundancy on a critical circuit and prevent splicing of wire into fuse holders or power connectors. Dual fuse installations have two lines wired in parallel. This configuration also allows for a greater distance from ECM to battery. See Figure "Power Harness with Single ECM and Dual Fuses" . The resistance requirement is unchanged.‪

Figure 13. Power Harness with Single ECM and Dual Fuses

Use the requirements listed in Table "Power Harness Length Criteria for Dual Fuse Installations" to determine minimum cable gage for a dual fuse installation. The cable gage is based upon harness length from the battery source to the ECM.‪

UNITED STATES‪			INTERNATIONAL *‪
Length from ECM to Battery or Bus Bar (ft)‪	Minimum Wire Size (Ga.)‪	Total Resistance of Maximum Length (mΩ)‪	Length from ECM to Battery or Bus Bar (m)‪	Minimum Wire Size (mm2 )‪	Total Resistance of Maximum Length (mΩ)‪
0 to 28‪	12‪	24.8‪	0 to 6‪	2.5‪	22.80‪
28 to 44‪	10‪	24.57‪	6 to 10‪	4‪	23.55‪
44 to 70‪	8‪	24.58‪	10 to 14‪	6‪	21.98‪
70 to 110‪	6‪	24.7‪	14 to 26‪	10‪	23.66‪
110 to 178‪	4‪	25.0‪	26 to 40‪	16‪	23.20‪

* For international wire sizes, the harness length must be recalculated to meet the resistance requirement.

These lengths and sizes are based on the use of stranded annealed copper not aluminum wire. Splices must be soldered and sealed with a waterproof insulator. A heat shrink — dual wall epoxy encapsulating adhesive polyolefin is required.‪

Section 7.2.8.6
Power Harness — Single Fuse Installation

Single fuse installations have one line from the battery to the ECM. Single fuse installations are simpler and less expensive than dual fuse installations. See Figure "Power Harness with Single ECM and Single Fuse" .‪

Figure 14. Power Harness with Single ECM and Single Fuse

Use the requirements listed in Table "Power Harness Length Criteria for single Fuse Installations" to determine minimum cable gage for a single fuse installation. The cable gage is based upon harness length from the battery source to the ECM.‪

UNITED STATES‪			INTERNATIONAL *‪
Length from ECM to Battery or Bus Bar (ft)‪	Minimum Wire Size (Ga.)‪	Total Resistance of Maximum Length (mΩ)‪	Length from ECM to Battery or Bus Bar (m)‪	Minimum Wire Size (mm2 )‪	Total Resistance of Maximum Length (mΩ)‪
0 to 14‪	12‪	24.8‪	0 to 3‪	2.5‪	22.8‪
14 to 22‪	10‪	24.57‪	3 to 5‪	4‪	23.55‪
22 to 35‪	8‪	24.58‪	5 to 7‪	6‪	21.98‪
35 to 55‪	6‪	24.7‪	7 to 13‪	10‪	23.66‪
55 to 89‪	4‪	25.0‪	13 to 20‪	16‪	23.2‪

* For international wire sizes, the harness length must be recalculated to meet the resistance requirement.

These lengths and sizes are based on the use of stranded annealed copper not aluminum wire. Splices must be soldered and sealed with a waterproof insulator. A heat shrink — dual wall epoxy encapsulating adhesive polyolefin is required.‪

Section 7.2.8.7
Power Harness Installation Guidelines

The following guidelines apply to power harness installation. See Figure "Main Power Supply Shutdown for 12 or 24 V Systems" for main power supply shutdown.‪

Figure 15. Main Power Supply Shutdown for 12 or 24 V Systems

1. Power must be sourced directly from the battery. An electrically solid connection to the battery or bus bar is required so the battery can filter electrical noise from the power lines. Power for other vehicle systems must not be sourced from the power harness assembly. Do not use chassis ground.
2. Power and ground bus bars may be used. The bus bar must be connected to the battery posts with 0 AWG or larger wire depending upon the total vehicle current requirement. The connecting wires must be as short as possible to minimize circuit resistance. Do not connect the ground wire to the chassis ground.
3. Provide maximum physical separation of the power harness from other vehicle electrical systems. Other electrical system cables should ideally be at least three feet away from the power harness and should not be parallel to the power harness. These precautions will eliminate coupling electromagnetic energy from other systems into the power harness.
4. Use the following precautions when installing the power harness assembly:
   1. Do not route the power harness near any vehicle moving parts.
   2. Do not route the power harness assembly near exhaust system or any high heat source.
   3. Use a protective sheath and clips to prevent wires from being cut or frayed when weaving the power harness through the frame.

Section 7.2.8.8
Engine Sensor Harness

The following wire schematics support the ESH. See Figure "Engine Sensor Harness — Series 50G/60G Engine, Models 6067–TKG8 and 6047–TKG8" and Figure "Engine Sensor Harness — Series 50G Engine, Model 6047–MKG8" .‪

Figure 16. Engine Sensor Harness — Series 50G/60G Engine, Models 6067–TKG8 and 6047–TKG8

Figure 17. Engine Sensor Harness — Series 50G Engine, Model 6047–MKG8

Section 7.2.8.9
Vehicle Interface Harness

The Vehicle Interface Harness (VIH) is supplied by the vehicle manufacturer. The following wire schematic shows design requirements of the VIH. See Figure "Vehicle Interface Harness — Series 50G/60G Engine, Models 6067–TKG8 and 6047–TKG8" and Figure "Vehicle Interface Harness — Series 50G Engine, Model 6047–MKG8" .‪

Figure 18. Vehicle Interface Harness — Series 50G/60G Engine, Models 6067–TKG8 and 6047–TKG8

Figure 19. Vehicle Interface Harness — Series 50G Engine, Model 6047–MKG8