Detroit Diesel Troubleshooting Diagrams

The Barometric Pressure Sensor (BARO sensor) is mounted to the sensor bracket at the rear of the cylinder block just above the flywheel housing. The sensor sends an electrical signal to the ECM indicating barometric pressure. It is electrically connected to the ECM through the engine sensor wire harness. A hose is attached to the inlet of the sensor to protect it form dirt and prevent plugging. The ECM uses the data in controlling fuel delivery to the engine.

For knock protection, the Series 60 natural gas engines are equipped with a Knock Sensor and Signal Noise Enhancement Filter (SNEF) module. The knock sensor is located at the left rear of the cylinder head. The SNEF module is mounted on the left side of the cylinder block. The SNEF module receives electrical signals from the knock sensor and sends electrical signals to the ECM indicating knock level. The ECM uses this information to determine if the engine is knocking and adjusts ignition timing, air fuel ratio and throttle plate to protect the engine from excessive knock.

The Exhaust Gas Oxygen Sensor is mounted in the vehicle exhaust pipe within 12 inches of the turbocharger exhaust outlet in the top half of the pipe. The sensor is threaded into an M18 boss welded to the exhaust pipe. The sensor works in conjunction with an oxygen sensor interface module that is mounted to a sensor bracket located at the rear of the cylinder block above the flywheel housing.

The Series 60 diesel engine Fuel Temperature Sensor (FTS) is installed into the secondary fuel filter.The FTS sends an electrical signal to the ECM indicating fuel inlet temperature. The ECM uses this information to calculate fuel consumption.

The Fuel Pressure Sensor (FPS) is installed into the secondary fuel filter. The FPS is not used in all applications. The FPS sends an electrical signal to the ECM telling it what the engine fuel pressure is at any given speed.

The Coolant Level Sensor (CLS) is a two-piece sensor for DDEC II, and a single sensor for DDEC III/IV. The sensor probe (supplied by the vehicle, vessel or equipment manufacturer) is mounted in the top tank or overfill tank. For DDEC II the sensor module is mounted on the vehicle. The module sends an electrical signal to the ECM to indicate coolant level. Low coolant will activate the stop engine function or warning function.

The Timing Reference Sensor (TRS) is an electronic component that is mounted to the left side of the gear case, near the crankshaft centerline.

The sensor portion of the TRS extends through an opening in the gear case, and is positioned near the teeth of the timing wheel. A bolt, inserted through a hole in the TRS bracket, secures the TRS assembly to the gear case. The TRS connector is gray in color. ‪

The TRS sends a signal to the ECM. This signal is generated by a series of evenly spaced teeth on the timing wheel. As the timing wheel rotates with the crankshaft, a tooth passes by the TRS. These signals are used by the ECM to determine injector solenoid operation times and engine speed.

The Synchronous Reference Sensor (SRS) is an electronic component that is mounted to the rear of the gear case.

The sensor portion of the SRS extends through a hole in the gear case, and is positioned very near the rear of the bull gear. A bolt, inserted through a hole in the SRS bracket, secures the SRS assembly to the gear case. The SRS connector is black in color.

The Coolant Temperature Sensor (CTS) is mounted on the right rear corner of the cylinder head, behind the turbocharger. The CTS sends an electrical signal to the ECM indicating the engine coolant temperature. The CTS activates engine protection if coolant temperature exceeds the specified limits.