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Advanced E-TEC Rigging

by James W. Hebert

Previously I published an article on general topic of rigging a boat for Evinrude E-TEC engine. This second article continues that topic but looks into more advanced rigging problems and give mores details in regard to ICON Pro series gauges and to TRIM circuit configurations.

Table of Contents

ICON Gateway Module and NMEA-2000 Network Power

For boats equipped with an E-TEC engine that has ICON controls, there will generally also be an ICON Gateway Module installed. With ICON controls, the E-TEC engine's NMEA-2000 port is connected to the ESM Module under the engine cowling. This means that all the usual NMEA-2000 engine data is sent to the ESM Network, not to the NMEA-2000 network as would normally be done. To make the engine data available to a NMEA-2000 network, the ICON Gateway Module must be installed. The ICON Gateway Module connects between the Evinrude ESM Network (that is used to transport all the ICON control signals between the engine and the helm stations) and the NMEA-2000 network of the vessel. The similarly named ICON gauges, often used in conjunction with ICON controls, will connect to the NMEA-2000 network, via the Gateway Module.

The ICON Gateway Module is powered from its own dedicated 12-Volt power connection via the master power/key switch harness associated with the ICON electronic engine controls. This power is obtained from the battery that is being used with the E-TEC engine. The Gateway Module is activated from the ESM Network, and it powers up when the ignition key switch is turned to ON.

In addition to acting as a data gateway to transport E-TEC engine data to the NMEA-2000 network from the ESM Network, the ICON Gateway Module also acts as a power-node for the NMEA-2000 network. This practice is somewhat unusual in the wiring for NMEA-2000 networks with a single battery-supplied power source. (See MNEA-200: A Digital Interface for the 21st Century for more on network power for NMEA-2000.). It is more common that NMEA-2000 networks are powered by their own dedicated network power connection and not from attached devices that want to power the network. However, Evinrude designed their Gateway module to provide network power to the NMEA-2000 network which connects to it. They likely did this to simplify the installation of ICON controls with ICON gauges, and this is understandable if you confine the scope of the NMEA-2000 network to just ICON engine gauges from Evinrude. If the Evinrude plan is followed, the Gateway Module will be the power source for the network. Powering the NMEA-2000 network this way has several ramifications.

A NMEA-2000 network should not be powered simultaneously by multiple sources at several points along the backbone, and, if following that rule, the network to which the Gateway Module is connected should not be powered by another source. Note that network power is only intended to provide power to the network interface electronics of attached devices, and it is not intended to completely provide all power to all devices on the network. Some small sensors have very low power consumption, such as Lowrance EP-85R Storage Module, and they can be powered from the network, but most connected devices will also have their own dedicated power source.

Since the Gateway Module is powered from the same battery that runs the E-TEC, this means that the engine starting battery is going to be powering the NMEA-2000 network. Generally the engine starting battery should be isolated from the electronic equipment power. The isolation is recommended to prevent voltage sags or voltage spikes on the power bus from the engine starting battery from causing electronic equipment to lose power or shut off due to high voltage. With the Evinrude plan the NMEA-2000 network will be powered by the starting battery for the E-TEC.

Since the Gateway Module is only powered ON when the engine key is turned to ON, the NMEA-2000 network will go dead whenever the engine key is turned to OFF. This means the engine key must be kept ON in order to run the NMEA-2000 network. It is possible to keep the engine key in ON and not be running the E-TEC engine, but this will accumulate running time on the EMM. The EMM time is tracked separately from the engine operating time. If the engine key is left in ON to power the NMEA-2000 network, the EMM hours will begin to show many more hours than the E-TEC operating time. This discrepancy can lead to confusion in reading Engine History reports available from the E-TEC engine. Also, when the engine key is in the ON position, the fuel pump on the E-TEC will run and pressurize the fuel system. (There is no apparent harm in this that I can see, other than the discrepancy between EMM hours and engine hours.)

NMEA-2000 Network Power Separated

A solution to the problem of having the NMEA-2000 network powered by the Evinrude ICON Gateway Module is to split the network backbone into two segments, and power each segment separately. Splitting of the network backbone power into two segments is a completely acceptable practice. Use a special dual-power feed T-connector, or use of a special T-connector that breaks the power circuit at that point will allow separation of the network into two branches for power.

Dual-power-feed Connector

Several NMEA-2000 wiring device vendors sell specialized power connectors which provide to two power connections, each connection powering only one side of the network T-connector and network backbone. By inserting the dual-power-feed T-connector into the network backbone, the network on one side of the T-connector will be fed from the first power circuit, and the network on the other side of the T-Connector will be fed from the second power circuit. In the case of a network already being fed from a power source, this dual-power-feed T-connector could be used to isolate the network into two segments. The segment of the network that is to be fed from another source is isolated by not connecting any power feed at the dual-power-feed T-Connector for that side. The segment of the network that is to be powered through the dual-power-feed T-connector is supplied with power by connecting power only to the wiring that feeds that side at the dual-power-feed T-connector. The unused wires must be carefully insulated and stored.

          Power circuit             Power circuit
                  |      ||    |   |   |   |   |   |
                  |      ||    |   |   |   |   |   |
                  |      ||    |   |   |   |   |   Device1
                  |      ||    |   |   |   |   Device2
               Gateway   ||    |   |   |   Device3
                         ||    |   |   Device4
                         ||    |   Device5
                         ||   ICON Tachometer and other ICON gauges
                         ||to Power distribution
                         |insulated and not powered
PT = special dual-power-feed T-Connector

The NMEA-2000 network backbone power is split into to segments by use of a special dual-power feed T-connector in which the power circuit has been been split into two isolated segments. The Gateway Module is on on the portion of th network in which no power is being fed by the special dual-power-feed T-connector. The Gateway Module is on the network for data.

Using the dual-power-feed T-connector method is the best choice. It will require purchase of the specialized power feed. Maretron has such a device and its sells for about $38. If using this device be careful to first identify which leads power which side of the device. You must leave one side unpowered and insulate the power leads. Also, this device is not a Male-Female network segment device, so you will end up having to purchase another Network-Terminator as the gender will be incorrect on the present network terminator at one end. The Maretron power tap has connectors with sockets, so you will need terminators on each end with pins (usually identified as Male gender).

Special Network Backbone Connector to Split Network Power

A second method for splitting the network power on the network backbone is to insert a special backbone connector which blocks the power circuit at some point in the network backbone. The special connector does not carry the power of the network backbone through the wiring. This breaks the power feed at this point. On either side of the modified T-connector the network can then be powered by separate power feeds.

In the specific case of the Evinrude ICON control system and Gateway Module, the isolation of the network power can be made so that only the Gateway Module itself is located on the segment of the network backbone that has been isolated for power. This is shown schematically below.

    Power circuit                 Power circuit
               |    Power     |    |   |   |   |   |   |
               |    Block     |    |   |   |   |   |   |
               |              |    |   |   |   |   |   Device1
               |              |    |   |   |   |   Device2
           Gateway            |    |   |   |   Device3
                              |    |   |   Device4
                              |    |   Device5
                              |    ICON Tachometer and other ICON gauges
                          to power distribution panel

The NMEA-2000 network backbone power is split into two segments by use of a special network backbone wiring appliance in which the power circuit has been interrupted. The Gateway Module is on the network for data, but its power circuit does not power the other segment of the network. The other segment is powered by a conventional power-T and power connection

A special power-isolating network backbone wiring appliance is available from Garmin for about $20. If this wiring appliance is used, the network will require a power feed using a conventional power-node wiring appliance. The isolated network can be fed from an isolated battery that is not used for engine starting.

Advantage of Split Network Power

Isolating the network power from the Gateway Module and installing a separate NMEA-2000 network power feed will permit the NMEA-2000 network to be powered even when the ignition key of the E-TEC engine is in the OFF position. This will allow devices to communicate on the NMEA-2000 network with the engine power shut off. In this way a NMEA-2000 display device can continue to access data from other devices. For example, a display device could continue to access data from a Storage Device on the network or from a GPS receiver on the network.

Details of Split Network Power Installation

The details, including part numbers and cost of components, for adding a split power circuit are given in a separate article. The article also describes some problems or anomalies that have been observed in the operation of certain devices when then network is operated with some devices not powered up.

TRIM Circuit

The configuration of the electrical circuit used to sense the engine trim position, the TRIM circuit, is quite variable with rigging of an E-TEC, and the configuration depends on the gauge, harnesses, and method being used. There are four basic variations:

Simplified schematic of trim circuit variations
The TRIM circuit has four basic variations. All are slight modifications of how current will be supplied to the TRIM SENDER via Pin C of the Trim Connector under the engine cowling. The TRIM SENDER is connected to the engine wiring harness by the conductor with TAN-with-WHITE insulation.

Conventional Analogue Trim Gauge

For many years the trim circuit in Evinrude engines has operated using a simple circuit. The boat's 12-Volt battery current was supplied through a trim gauge. The gauge connected to a 100-ohm variable resistor. The variable resistor was mechanically linked to the engine mounting bracket, and its resistance changed as the engine was tilted. A milliammeter connected in a bridge circuit indicated the engine position based on current flow through a somewhat complicated resistor bridge. The effect of the resistor bridge in the trim gauge was to place about a 47-Ohm resistor in series with the current source to the TRIM SENDER rheostat.

Simplified schematic of trim circuit.
The basic operation of the trim circuit is shown above. The two resistors form a voltage divider. As the 100-ohm variable resistor moves with the engine trim, the voltage across the resistor changes.

This same decades-old system of trim position indication can still be used with an E-TEC engine and conventional gauges. The System Check Wiring harness (also known as the MWS wiring harness) is used. The analogue gauge near the helm is wired to conductors in the harness. The E-TEC connects to the harness and carries the trim circuit to the trim sensor via its own internal wiring harness. The analogue gauge indicates the trim position as it has always done. At the same time, the engine management module (EMM) in the E-TEC monitors the voltage at the junction of the trim gauge resistance (~47-Ohm) and the variable 100-ohm sender resistance. This input is processed by the EMM and becomes a data value on the E-TEC NMEA-2000 output data.

Being a modern device, the EMM can perform a calibration of the trim signal as it converts it from an analog voltage input into a digital signal. In every installation there is a limit to the maximum down trim position, usually created by a mechanical stop bar placed in the engine mounting bracket. This position can be set in the calibration as the zero-trim position. There is also a maximum trim up position, the point where the trim-tilt system shifts to high speed movement, and this position can also be set as the 100-percent trim position. In this way the E-TEC EMM will accomplish a calibration of the analogue voltage that represents trim position into a digital signal with values of 0 to 100.

In this circuit, the approximately 47-ohm resistance is part of the analogue trim gauge, and the WHITE with TAN STRIPE conductor in the MWS harness carries this circuit to the E-TEC which then connects the 100-ohm variable resistor of the trim sensor. The analogue gauge shows the trim position as it always has, and the E-TEC EMM uses the same sensor and its varying voltage to create a NMEA-2000 signal for trim position, which can be calibrated to the individual boat installation. Both the conventional trim gauge and any attached NMEA-2000 devices will show the trim position.

NMEA-2000 Gauges with I-Command Harness

If no conventional analogue trim gauge is being used, the typical rigging will employ a different harness, called the I-Command Harness. This harness anticipates that there will not be analogue gauges at the helm and it does not break out any conductors for wiring to a conventional trim gauge. Instead, the harness incorporates its own 47-ohm 5-watt resistor in the harness assembly. This resistor performs the same function as the one that is on a conventional trim gauge, that is, it provides a source of current to be sent to the trim sender on the WHITE with TAN STRIPE conductor. Instead of being on the back of the trim gauge, it is wired into the harness. The trim circuit otherwise works exactly as it does with the analogue gauge present: the E-TEC senses the voltage, converts it to a digital value, and sends the signal as part of the NMEA-2000 engine data to the network. Any device on the network that can show trim data can show the trim value from the E-TEC. This method is the recommended practice for the E-TEC for I-Command or other NMEA-2000 gauges.

NMEA-2000 Gauges with System Check or MWS Wiring Harness

Some boats had existing rigging with the System Check or MWS harness but wanted to go to NMEA-2000 gauges and not also have a dedicated traditional trim gauge. In this situation the System Check harness can be used if an external 47-ohm 5-watt resistor is added. The resistor can easily be added by wiring it to the leads which were intended for the conventional analogue trim gauge. The 47-ohm resistor is just wired between the 12-Volt circuit (VIOLET) and the trim sender circuit (WHITE with TAN STRIPE). Doing this creates the same arrangement as exists with the I-Command Wiring Harness. Electrically there is no difference. The simplest method for most boaters to obtain the necessary resistor is to purchase one from a local electronics store. A 47-Ohm 5-Watt resistor is recommended.

NMEA-2000 Gauges and TRIM Circuit

In either of the instances described above, the trim position is sent to the NMEA-2000 network from the EMM as a digital value in a range from zero to 100 in the parameter group PGN127488, Engine Parameters, Rapid Update. This is shown schematically below:

Simplified schematic of NMEA-2000 trim circuit.
The EMM in the E-TEC monitors the voltage at the trim sender and converts this to a digital value in a range of 0 to 100 that is sent to the network. There is a calibration function available in the EMM to adjust the conversion process to produce the most useful range of values.

ICON Pro Series Gauges with ICON Controls

ICON Pro Series gauges are now considered as a special case. One of the goals of the ICON Pro Series gauge product line was to simplify rigging. (We have seen this already in the provision of the ICON system to power the NMEA-2000 bus to which ICON gauges will attach.) When ICON Pro Series gauges are used in conjunction with ICON controls, the trim circuit is handled differently than in the three situations mentioned above. The existing trim circuit connector on the E-TEC is no longer connected to any part of the helm or dash wiring via any sort of harness. Instead, the trim circuit on the E-TEC is connected to the ESM Module of the ICON control system under the engine cowling--it never goes to the helm. The current for the 100-ohm resistor is supplied by the ESM Module. The voltage at the junction of the ESM module and the 100-ohm trim sender is still connected to the EMM. The EMM continues to convert this signal into a digital value of 0 to 100 for trim position.

ICON Pro Series Gauges without ICON Controls

NMEA-2000 Data Source for Trim

ICON Pro Series gauges can be installed without using ICON controls. When this is done, the ICON Pro Series gauges will function like any other NMEA-2000 gauge. The E-TEC EMM will send data about trim position on the network. The ICON Pro RPM gauge will receive this data. As in other instances, the trim sensor must have some current supplied so the EMM can sense it. If the trim sensor is provided with current using an I-Command Harness or by a System Check harness with an added external 47-ohm resistor, the trim circuit will function, the E-TEC's EMM will convert the signal to a NMEA-2000 data value, and the ICON gauges will receive and display that signal. In this way, the ICON gauges will act just like any NMEA-2000 gauge as described above.

Analogue Input Data Source for Trim

If ICON Pro Series gauges are used with a boat that has the System Check harness, that is, a rigging situation in which there is no 47-ohm resistor supplying current to the 100-ohm trim sender, there is another method of utilizing the trim sender that is unique to ICON gauges. This alternate method is also very useful with Evinrude E-TEC three-cylinder engines, because the EMM in those engines does not have the capability of sending any trim data on the NMEA-2000 network.

The ICON Pro RPM gauge system provides several of its own analogue input sensors, and the trim sender on the E-TEC can be connected directly to one of the ICON Pro Tachometer gauge analogue inputs, which will then sense the resistance of the trim sensor directly, without needing an external 47-ohm resistor to supply the current. (In fact, if this method is used, be sure to NOT have any external voltage connected to the trim sender circuit via the wiring harness.)

To accomplish this rigging, the WHITE with TAN STRIPE conductor (in the MWS or System Check rigging harness at the helm end) is wired to the ICON Pro RPM gauge ANALOG2 input circuit (at P1-7 on the breakout). This allows the ICON Pro RPM gauge analogue input to see the sensor resistance directly. However, the ICON gauge must then be re-configured to become aware that it should find the trim input from its own sensor rather than from the NMEA-2000 data signal on the network. This method eliminates the need for a 47-ohm resistor. This procedure to let the system know it will be looking for the trim signal on its own input, not from the NMEA-2000 source, is explained in the ICON gauge installation literature and can be accomplished using the front panel controls on the ICON Pro Tachometer gauge. For more details see a separate article on this method.

If rigging for the ICON Pro RPM gauge analogue input (typically P1-7)) to read the TRIM SENDER resistance, there may be a drawback. I don't know for certain if the E-TEC EMM can be calibrated to read the voltage on the trim sender when the sender is connected to the analogue input of the ICON Pro RPM gauge. The voltage supplied by the ICON Pro RPM gauge to read the resistance is only about 1.2-Volts, and this may be too low for the E-TEC EMM to properly read. Generally this method won't be used with E-TEC engines where the EMM can read the trim sensor itself.

For E-TEC engines of 90-HP or less, the EMM cannot read the trim sender, and the EMM in those engines does not send an NMEA-2000 data about engine trim. For those E-TEC engines using the analogue input on the ICON Pro RPM gauge is the only way to get a reading of TRIM on the ICON Pro Series gauges.

The ICON Pro RPM gauge will communicate with an ICON Accessory two-inch dedicated TRIM gauge downstread on the ICON gauge bus, and engine trim will be shown, for example, on the ICON Accessory 2-inch dedicated TRIM gauge, no matter what source was used in the ICON Pro RPM gauge to get the data.

NMEA-2000 Data and Analogue Input

In the case of the three-cylinder E-TEC engine without any means for the EMM to develop trim data itself and send it to the NMEA-2000 network, the ICON Pro RPM gauge analogue input is a good option. There remains, however, one disadvantage to this method: the ICON Pro RPM gauge will not be sending trim data to the NMEA-2000 network; it seems to only send it to the local ICON gauge network. This suggests that if there is another multi-function display on the NMEA-2000 network that could display engine trim, there won't be any data being sent from the ICON Pro RPM gauge to the NMEA-2000 network; without data on the network, trim position cannot be shown on the NMEA-2000 network. More information about this problem is provided in another article.

ICON Trim Calibration

One of the advantages of the ICON gauge system is the built-in calibration adjustment for the trim signal. Prior to the ICON gauge system, the trim signal being sent from the E-TEC EMM to the NMEA-2000 network could only be calibrated to the individual boat installation using the Evinrude E-TEC Diagnostic Software. This software was generally only available to authorized dealers. Typically a dealer would perform a trim calibration as part of the initial installation and rigging of a new E-TEC engine for a customer, prior to delivery of the boat. Once the E-TEC installation left the dealer, the trim values in the NMEA-2000 signal could not be changed. ICON gauges introduced a new function that allows the trim signal that will be displayed on the ICON gauges to be calibrated by the boat owner, without involving the dealer and the Diagnostic Software. This was seen as an advantage for ICON gauges over I-Command gauges. And, quite impressively, the calibration works with with data source for the trim; that it, it works with both the NMEA-2000 data from the engine or the analogue input data to the ICON Pro RPM gauge itself.

There is one slight problem with the ICON trim calibration: it only affects the data shown on the ICON gauges. If you want to display engine trim on another NMEA-2000 display, the ICON calibration will not be in effect. The EMM trim calibration will be used for the NMEA-2000 network signal. This results in a bit of a confused situation if the trim is shown simultaneously on both the ICON gauges and on another NMEA-2000 display devices.

If you want the trim values on both ICON and NMEA-2000 devices to match, you must perform the calibration on both systems simultaneously. You will need the Evinrude Diagnostic Software to accomplish this. The method is as follows:

I have simultaneously calibrated my ICON and NMEA-2000 gauges using this method, and the engine trim position shown on both gauges matches perfectly.

E-TEC Trim Calibration

As mentioned above, the E-TEC EMM can be calibrated to produce a NMEA-2000 trim signal that is adjusted for the individual E-TEC on the transom of the boat, permitting the maximum (100) and minimum (0) data values to correspond with the actual trim limit positions of the individual installation. It is also believed that until this calibration process has been performed (typically by the dealer using the Diagnostic Software) there will be no trim data values available on the NMEA-2000 network. Be sure that your dealer has configured the NMEA-2000 calibration, or you won't see any data for trim on any NMEA-2000 gauge. (If you have the Evinrude Diagnostic software, you can perform the trim calibration procedure yourself.)

General Advice About Diagnosis of Problems with the TRIM Circuit

Problems in the TRIM circuit will typically be found in three distinct realms:

If all three elements of the TRIM signal wiring, configuration, and display have been successfully accomplished and no data for TRIM is seen, a deeper investigation into a new realm, the data traffic on the NMEA-2000 network, will be necessary. By monitoring the NMEA-2000 network traffic it should be possible to confirm the datagram is being sent for TRIM to the network from the E-TEC. If that datagram is not seen being sent, the problem is with the E-TEC, its EMM, the configuration of the EMM, or the TRIM circuit wiring. If the datagram is seen being sent, the problem is more likely in the display device.

Typically network diagnostic analyzers for NMEA-2000 are not on-hand for most boaters or even for most dealers. If a NMEA-2000 network analyzer is not available, you can instead test for the source of the problem by substitution. Substitute a different display device. Try a suspected display device on a different network. By various substitution of components the cause of the problem may be able to be isolated to a particular component.

It is my preference to begin diagnosis of electrical problems by investigating the simplest and most easily tested components, and by testing them to rule them out as causes of the problem. In this method, one begin with simple tests of simple components, and progresses to more complex tests of more expensive components.

In the TRIM circuit, the most basic diagnostic test is to measure the voltage at the TRIM sensor, and to verify there is voltage present, that it changes as the sensor arm is moved, and that this voltage is conveyed to the E-TEC EMM. The details of where the TRIM sensor voltage is conveyed to the EMM are shown (above) in the illustrations. At this point, however, it would be wise to have on hand the complete schematic diagrams of the E-TEC wiring and related harnesses. Accurate schematic diagrams are extremely helpful in make a diagnosis and locating a problem in an electrical circuit.

Follow-up Questions

If readers have any questions about the material presented, please contact the author via email.

Copyright © 2012 by James W. Hebert. Unauthorized reproduction prohibited!

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