Suzuki Precision Control Explained: Drive-by-Wire Throttle and Shift, Which Models Have It and What Changes for the Owner

A Suzuki drive-by-wire outboard has no throttle or shift cables between the helm and the motor. The set-up manual puts it in one sentence: the DBW control box "does not use the mechanical remote control cable for shift/throttle control. The shift/throttle control is actuated electronically by an SPC system." SPC is Suzuki Precision Control. The lever sends a signal through the main wiring harness to the boat control module (BCM) and the engine's ECM, and the motor opens its own throttle and shifts its own gear. For the owner that means a Start & Stop switch instead of a key cylinder, a lever that will not shift with the engine stopped, a row of switches on the control box, troll mode set from the gauge, and a few "Check" messages that exist only on these motors.

The electronic-shift models in the manuals we have are the DF115BG/DF140BG, DF150AP/DF175AP/DF200AP, DF250AP/DF300AP and DF300B/DF350A (the same manual covers the DF300BMD/DF350AMD); the store's harness fit list adds the DF325A. The owner's manuals say "electronic throttle and shift systems"; the set-up manual says "Suzuki Precision Control System" and "DBW"; the store calls the current harness and controls Suzuki Precision Control 2.0 (SPC 2.0), for 2022 and later models. A plain DF150A, DF175A or DF200A (no P) is a cable motor.

What changes at the helm

Starting

All four manuals describe the same Start & Stop switch: "The engine can be started with the remote control handle at the neutral position." On the DF150AP/DF175AP/DF200AP one press runs the starter for 3 seconds; it is limited to five seconds of continuous operation, then stops, and the manual says to wait about ten seconds before trying again. On the DF250AP/DF300AP and DF300B/DF350A the limit is four seconds. Without the optional Keyless Start System the main switch simply turns the engine's power on and off; with it, the fob has to be in range and the system is turned ON from the main switch (DF150AP/DF175AP/DF200AP) or the engine switch (DF115BG/DF140BG, DF250AP and up). Fob, passcode and emergency start are in the keyless start and emergency passcode guide.

The lever

The lever moves like a mechanical single-lever control: forward "thru approx. 17.5° on (F) side" to shift, and further to open the throttle. The type B box has a shift lock button to push in before leaving neutral. Two things are different from a cable box:

• It will not shift with the engine stopped. "When the engine stops, the clutch moves to the neutral position irrespective of the position of the remote control lever," and it cannot be shifted to forward or reverse while the engine is stopped.
• It will not shift at high engine speed. On the DF115BG/DF140BG, DF250AP/DF300AP and DF300B/DF350A, "if gear shifting is attempted while the engine speed is high, the buzzer sounds twice" and the N indicator on the gauge blinks; move the lever back to fully closed. The DF150AP/DF175AP/DF200AP manual we have does not print this note.

The switches

The switches sit on the remote control box or a separate control panel. "Not printed" means the owner's manual we have does not describe that switch for that family.

Throttle Only "holds the shift position in neutral, thereby allowing operation the throttle without changing the shift position". It works only with the lever in neutral: hold the switch until one short beep and the THROTTLE ONLY LED comes on. With the lever out of neutral the LED blinks and the buzzer sounds. If the mode cannot be selected, turn the power off, wait 20 seconds and turn it on again (DF150AP/DF175AP/DF200AP: Keyless Start System OFF, 20 seconds, ON).

Station Select moves control between two helms and lights the SELECT LED at the chosen one. It is "enabled only when the remote control handle at the 1st and 2nd driving stations are at the neutral position"; the 1st station is selected at power-on, and if control will not hand back from the 2nd station, use the same 20-second power cycle. Engine Synchronize matches engine speed to the port engine in forward cruising, not at idle or full throttle; Center Engine Control links or unlinks the center engine of a triple with the port engine; 1 Lever lets the PORT handle run all engines. Center Engine Control and 1 Lever work only with all levers in neutral; sync comes on and 1 Lever drops out at every power-on.

Power trim and tilt has one catch at the ramp: "The tilt up and tilt down switches cannot be activated when the power off." Tilt before you shut the system down. For a PTT that will not move with the power on, see power trim and tilt troubleshooting.

Troll mode

Troll mode holds a set engine speed in gear, from the multi-function gauge or an optional troll mode switch:

1. Shift into forward or reverse with the throttle fully closed. It will not switch on in neutral, and "will not function properly until engine is at normal operating temperature."
2. Press and hold [MENU] on the gauge; at "Start Troll Mode?" select YES and press [SET]. One beep confirms. With the optional switch, hold UP or DN instead.
3. Each press moves the set speed 50 r/min with one short beep; at the lower limit the speed will not change and three long beeps sound.
4. To cancel, shift all levers to neutral or raise engine speed to 3000 r/min or more; two short beeps confirm.

On a two-station boat, start it at the station whose SELECT LED is on, or you get "Check Station Setting". "Check Troll Condition" means the lever is not in gear or the throttle is not fully closed; "Check Troll System" means the motor's ECM and BCM do not support troll mode.

What the system does on a fault

These cautions exist only on the electronic-shift models; the overheat, oil pressure and Check Engine cautions are in the warning light and buzzer guide. All four owner's manuals print the same five; on the DF150AP/DF175AP/DF200AP the red lamp on the control panel also lights for the first two.

Every manual gives the same instruction: "If this system activates for no apparent reason, there may be a problem with the system. Consult your authorized Suzuki marine dealer." No owner's manual prints a reset. The set-up manual adds one cause for a motor that shows Check Control Unit C, sounds the buzzer and will not crank: an improper combination of BCM and ECM, which is dealer work. A "Check Engine" message with a number is the engine diagnostic system, not the control system; see the diagnostic codes page. If the motor is under warranty, check with your dealer before anyone opens the harness.

Five cautions the set-up manual prints for the electronic system

From the DF150AP/DF175AP/DF200AP set-up manual; they apply just as much to an owner adding electronics or swapping a battery:

1. "Do not cut or extend the wiring harness and lead wires." Water can enter at the joint and cause a continuity error, "resulting in shifting and throttle control errors."
2. Install radios, antennas, navigation and other equipment "more than 50 cm (20 in) away from the BCM and the outboard motor."
3. Battery order matters: "First turn the main switch OFF, and disconnect the battery's negative terminal, and then disconnect the positive terminal." To reconnect: main switch OFF, positive first, then negative.
4. "Ensure all connections are correct and tight, and plug all connectors not in use with a waterproof cap."
5. Mount the BCM with its connector facing downward, where the temperature does not exceed 75 °C (167 °F).

Rigging: harness, gauge and calibration

There are no control cables to measure; the helm-to-motor connection is the main wiring harness. The store's SPC 2.0 main wiring harness (36620-98L00 / 36620-98L10) is listed for the DF115BG/140BG, DF150AP/175AP/200AP, DF250AP/300AP and DF300B/325A/350A, 2022 and later only, and "does not fit mechanical controlled engines"; for an earlier motor, the store confirms fitment from the model code and serial number on the ID plate. For a chartplotter, the engine interface cable 990C0-88149-357 sends engine data over NMEA 2000 (one per engine) and the NMEA 2000 cable kit builds the backbone Suzuki displays need to show speed.

Calibration is dealer work. The set-up manual: "Electronic calibration is required before use. After installation of this product, the Suzuki Precision Control System requires electronic calibration, which should be performed only by a person who has been specifically trained in the Suzuki Precision Control system." It is done with Suzuki Diagnostic System software Version 8.60 (see SDS explained). The DF250AP/DF300AP and DF300B/DF350A set-up manuals also describe a quick calibration without SDS when the BCM and ECM are not yet configured, done at the motor's PTT DN switch (held at least 3 seconds); on success "the high-pressure fuel pump operates, the buzzer triggers for 0.2 seconds, and the completion display appears in the gauge." For used-motor buyers: "The ECM or BCM calibrated in one boat cannot be reused in another boat."

Mechanical vs drive-by-wire

Differences the DF150A/DF175A/DF200A (cable) and DF150AP/DF175AP/DF200AP (electronic) owner's manuals actually print:

Parts for this job

Start with the SPC 2.0 main wiring harness and the Suzuki Precision Control 2.0 collection; control boxes are under digital controls and mechanical controls, displays in the gauges and instruments collection. Have the model code and serial number from the ID plate ready. Orders over $149 ship free to the lower 48.

Sources: Suzuki owner's manuals for DF115BG/DF140BG (99011-99L20-03B), DF150AP/DF175AP/DF200AP (99011-96LD0-03B), DF250AP/DF300AP (99011-98JB0-03B), DF300B/DF350A (99011-98L60-03B) and DF150A/DF175A/DF200A (99011-96LC0-03B); Suzuki set-up manuals 99505-96L70-01E (DF150AP/DF175AP/DF200AP), 99505-98J40-01E (DF250AP/DF300AP) and 99505-98L40-01E (DF300B/DF350A). Figures are Suzuki's published values; confirm against the manual for your model year and serial number.