14751-ZV5-004 Honda SPRING, VALVE (CHUO SPRING) (Honda Code 3701612).

Table 1
Diagnostic Codes Table
J1939 Code and Description Conditions which Generate the Code System Response
190-8 Engine Speed: Abnormal Frequency, Pulse Width or Period The Electronic Control Module (ECM) detects an intermittent loss or complete loss of the signal from the speed/timing sensor.
The engine control switch has been in the RUN position for at least 3 seconds. The code is logged.
The red stop lamp is illuminated.
The engine is shut down.
637-11 Engine Timing Sensor : Other Failure Mode The engine has failed the automatic timing calibration during engine start-up. The code is logged.
The value of the timing offset that has been stored in memory will be used. This value will continue to be used for the timing calibration until the diagnostic is resolved.
678-3 ECU 8 Volts DC Supply : Voltage Above Normal The 8 V sensor supply voltage has risen above 8.8 V for 1.5 seconds.
The engine control switch has been in the RUN position for at least 3 seconds. The 190-8 diagnostic code is suppressed while this code is active.
The code is logged.
The amber warning lamp is illuminated.
The service tool displays "Error Indicator" on the status screen for this parameter.
678-4 ECU 8 Volts DC Supply : Voltage Below Normal The 8 V sensor supply voltage has dropped below 7.2 V for 1.5 seconds.
The engine control switch has been in the RUN position for at least 3 seconds. The 190-8 diagnostic code is suppressed while this code is active.
The code is logged.
The amber warning lamp is illuminated.
The service tool displays "Error Indicator" on the status screen for this parameter. This engine utilizes two speed/timing sensors to detect the speed and the timing for the engine. The primary (camshaft) speed/timing sensor is used to detect engine speed and camshaft position during engine starting and also while the engine is running. The secondary (crankshaft) speed timing sensor is used only during engine cranking in order to determine top center of the No. 1 cylinder. Use this procedure to troubleshoot electrical problems with the circuit for the primary (camshaft) engine speed/timing sensor. For information related to troubleshooting the secondary engine speed/timing sensor, refer to Troubleshooting, "Speed/Timing (Secondary) - Test".
Illustration 1 g02644586
Features machined into the cam gear for speed/timing detection
The primary speed timing sensor utilizes a series of holes that are machined into the face of the cam gear to establish a signal. The pattern of holes includes two holes that are strategically spaced in order to provide a unique signal pattern to the ECM. The ECM utilizes the signal pattern to locate top center for the No. 1 cylinder, initiate ignition for the cylinders, and for engine speed determination.
Illustration 2 g02644459
Features machined into the flywheel for speed/timing detection
Similarly, the secondary speed timing sensor utilizes a series of holes that are machined into the outer surface of the flywheel to establish a signal. The pattern of holes includes two holes that are strategically spaced in order to provide a unique signal pattern to the ECM. The ECM utilizes the signal pattern to locate top center for the No. 1 cylinder.If the ECM detects a problem with the primary speed/timing sensor signal, the engine will not start and the engine will not run. If the ECM loses the signal from the secondary speed/timing sensor with the engine stopped, the engine will not be able to start. If a problem with the signal from the secondary speed/timing sensor occurs while the engine is running, the engine will continue to run.A timing offset is determined during each engine start-up. The value of the timing offset is stored in the non-volatile memory of the ECM until the successful completion of the next engine start-up. If a failure mode for the crankshaft speed/timing sensor is detected during engine start-up, the timing offset stored in ECM memory will be used. This value will continue to be used for the engine timing calibration until the diagnostic is resolved. A timing calibration cannot be performed manually on this engine. Note: The primary speed/timing sensor is an active sensor that utilizes an 8 V supply voltage and integrated circuitry. Do not attempt to troubleshoot the sensor by measuring resistance across the terminals of the sensor.If a problem is detected with the signal from the speed/timing sensor during engine operation, the ECM will shut down the engine. The ECM activates the above diagnostic code.A timing offset is determined during each engine start-up. The value of the timing offset is stored in the non-volatile memory of the ECM until the successful completion of the next engine start-up. If a failure mode for the crankshaft speed/timing sensor is detected during engine start-up, the timing offset stored in ECM memory will be used. This value will continue to be used for the engine timing calibration until the diagnostic is resolved. A timing calibration cannot be performed manually on this engine.The least likely cause of this diagnostic code is a problem with the ECM.
Illustration 3 g02639798
Schematic for the primary engine speed/timing sensor
Note: Due to certain regulations for this application, the harness for the speed/timing circuit contains an unused shield circuit.
Illustration 4 g02640316
Location of the speed/timing sensor (front side engine view)
(1) Speed/timing sensor
Illustration 5 g02640318
Location of the connectors for the primary speed/timing sensor (top side engine view)
(2) P2 ECM connector
(3) Engine harness connector (for incendive electrical devices)
Illustration 6 g02640416
Terminal locations at the P2 ECM connector
(P2-29) +8 V sensor supply
(P2-42) Engine speed/timing signal