79396 Mercruiser PLATE, BEARING

Improper grounding can cause uncontrolled or unreliable circuit paths and electrical noise resulting in damage to the engine bearings, and other engine components.
Proper grounding of the unit and the engine electrical systems is necessary for proper performance and reliability.Negative Battery Connection
All return paths to the negative battery must carry any likely fault currents.The starter should be connected directly to the negative battery post. The alternator must be connected to the negative battery, bus bar, or negative side of the starting motor.Negative Battery Connection for Multiple Engines
Illustration 1 g01635383
Isolated components
If multiple bus bars are used to connect components to the negative battery, a common reference should be provided. All bus bars must be wired together for proper engine synchronization for multiple engine installations.Welding on a Vessel that is Equipped with an Electronic Controlled Engine
Refer to the appropriate Troubleshooting Guide for more information about welding on a vessel that is equipped with an electronic controlled engine. Also refer to the appropriate Operation and Maintenance Manual for more information about welding.Switched Positive Battery and Unswitched Positive Battery
Illustration 2 g01264533Note: All battery connections to the ECM must be utilized in order to prolong the service life of the ECM.The electronic control system can operate on either a 12 V electrical system or a 24 V electrical system. The switched positive battery and the unswitched positive battery connections to the ECM are made at the P61 Customer connector.The ECM receives electrical power through the input for the switched positive battery. Protection for this circuit must be rated at 15 Amp (12 V or 24 V system).The input for the unswitched positive battery is used to power the ECM memory that contains maintenance information and certain logged diagnostics. Protection for the unswitched positive battery circuit is specified as 20 Amp.Powering the electronic control system through dedicated circuits with circuit breakers reduces the possibility of performance problems of the electronic control system. This also minimizes the chance of an engine shutdown due to a short in the electrical system. Additional loads should not be connected between the ECM and the circuit protection for the ECM.Note: Do not use in-line fuses for circuit protection. Caterpillar recommends the use of circuit breakers for circuit protection. Circuit breakers should be located with other devices for circuit protection in a centrally located, dedicated panel. If circuit breakers that automatically reset are used, consideration of the environment of the location of the breaker is critical and the effect on the trip point is critical. The trip point of some circuit breakers can be reduced below the rated trip point if the circuit breaker is exposed to high temperatures. This reduction can cause intermittent shutdowns that result with needless replacement of electronic components.Suppression of Transient Voltage
The installation of transient suppression at the source of the transient is recommended. Refer to Illustration 4. Caterpillar follows a stringent electrical environment standard that is similar to SAE recommended practices.The use of inductive devices such as relays and solenoids can result in the generation of transient voltage in electrical circuits. Transient voltage that is not suppressed can exceed SAE specifications and lead to the degradation of the performance of the electronic control system.
Illustration 3 g01264857
Use of a diode in a relay as a transient voltage suppressor
The OEM should specify relays and solenoids with built-in voltage transient suppression. Refer to Illustration 3 for ways to minimize transient voltage from relays and solenoids without built-in voltage transient suppression. Techniques include the installation of a diode or resistor of the proper size in parallel with the solenoid or the relay coil. Other techniques may also be used.Inductive devices such as relays or solenoids should be located as far as possible from the components of the electronic control system.Wiring harnesses that are installed by the OEM should be routed as far as possible from the wiring harness of the electronic control system in order to avoid problems that are associated with electrical noise.Examples of devices that require suppression of transient voltages include any device that switches inductive loads on and off. The following list provides examples of such devices:
Solenoids (trim tab solenoids, etc)
DC electric motors
Relays that use the same power and ground as the sensorThe following list provides other examples of situations that may cause transient voltages:
Improperly grounded electronic components
Improperly grounded cable shields
Improperly grounded antennas
Signal wires that are installed too closely to power wiresAll of the components that are connected to the ECM must have return wires (ground) that are connected to the engine's − Battery. The return wires (ground) should be connected as close to the battery as possible. Caterpillar recommends the use of a separate return wire for each component. Each return wire (ground) should be attached to the engine's − Battery bus bar.Caterpillar recommends the use of a 218-4935 Arc Suppressor on all inductive devices such as relays and solenoids. The 218-4935 Arc Suppressor is not polarized. This arc suppressor can be wired into the circuit without any concern for the direction of current flow.
Table 1
Required Parts
Part Number Description Quantity
218-4935 Arc Suppressor 1
155-2270 Connecting Plug Kit (2-PIN) 1
186-3736 Connector Socket 2
130-5300(1) Clip 1
130-5301(1) Clip 1
(1) Optional mounting clips