Depending on the year of manufacture, some 70's, 80's and some early 90's vintage boats had a different wiring color scheme than what has become standard today. Listed below is the comparison color code charts.
 If considering re-wiring an older unit; it is best to update all the wiring colors and not to mix the two codes. However, if you are just making a minor repair... stick with the original color code used in the rest of the boat.

Special Note: ABYC revised the marine electrical standards which started to show up in some boats as early as the 1996 model year. A big change is that the 12 volt black ground wire color was changed to making  "Yellow" an optional color as a ground wire. This is currently showing up primarily with the black battery cables, between the negative battery post and engine block, being replaced with yellow ones. There are other changes as well to marine 12 volt wiring so, be aware.

  With the addition of electronic fuel injection and other modern engine control systems, color codes and wiring systems are getting more complicated. Be very careful when testing wires for power and/or continuity. Use the color charts below as reference only. Consult your owners manual.

 See this color code page for misc brands and comparisons. (Includes Force, Honda, OMC, Suzuki, and Yamaha.)

 See current Mercury Outboard and some of the recommended ABYC color codes below. 



 In this chart, "Old Color" refers to a color code used by Mercury Marine, and others, previous to an accepted standard color code adopted in the 70's.

Direct Current (DC) Systems (under 50 volts)

Old Color   (BIA) Color               Where Used

Black         Black                          All Grounds

                 Black/Yellow            Ignition kill circuit

Black         Brown                     Alternator charge light
                                                 Pumps (bilge, live-well, etc.)
                                                 Reference Electrode - MerCathode

                 Brown/Orange         Power feed to Auto-bilge switches

Black         Orange                    Accessory common feed 
                                                 Distribution Panel to Accessory switch
                                                 Anode Electrode - MerCathode

Red/White    Orange                 Alternator Output to Ammeter

Blue         Lt. Blue/White              Trim -"Up" Switch

Brown          Gray                        Tachometer Signal

                     Dark Gray               Navigation Lights

Green        Green/White               Trim -"Down" Switch

Green            Tan                         Water Temp. Sender to Gauge

Orange        Lt. Blue                     Oil Pressure Sender (10 Gauge)

Pink             Pink                          Fuel Gauge Sender to Gauge

Purple        Brown/White              Trim Sender to Trim Gauge

Purple        Purple/White               Trim -"Trailer" Switch

Red           Red                          Unprotected Wires from Battery

Red           Red/Purple                Protected (Fused) Wires from Battery
                                                  Protected (+12V) to Trim Panel

Tan           Purple/Yellow            Ballast Bypass

White         Purple                     (+12V) Ignition power feed from
                                                    Switch  (Instrument power feed)

Yellow        Yellow                   Bilge blowers
                                                Alternator field to reg. field terminal
                                                Starter Solenoid to Starter Motor
                                                  (MCM 470 and some Ford products)

Yellow        Yellow/Red            Starter Switch to Starter Solenoid
                                                  to Neutral Start switch

                  Tan/blue                 Warning system sense wire
                                                   (Audio warning)
                  Yellow/Black          Neutral Safety switch
                                                   (transmission mounted)
                 White/Green            Ignition module to Distributor
                                                 (Mercury Thunderbolt ignition)

                  White/Red              Ignition module to Distributor
                                                  (Mercury Thunderbolt Ignition) 

                  Dark Green            Bonding Wires (earth ground)

                  Dark blue               Cabin, courtesy, and instrument lights



Current general wiring colors used on Mercury/Mariner Outboard engines.


Where Used / Function


All Ground


Reference Electrode MerCathode System


Anode Electrode MerCathode System

Lt. Blue/White Stripe

Trim UP Switch

Lt. Green/White Stripe

Trim DOWN Switch

Brown/White Stripe

Trim Sender to Trim Gauge

Purple/White Stripe

Trim "Trailer" Switch


Tachometer Signal

Black/Yellow Stripe

Shorting or Stop Circuit


Fuel Sender to Gauge


Unprotected Wire from Battery

Red/Purple Stripe

Protected (Fused) Wire from Battery

Red/Purple Stripe

Protected (12 Volt +) to Trim Panel Control


Ignition (Switch) to 12 Volt Positive


Temperature Switch to Warning Horn


Temperature Sender to Temperature Gauge

Tan/Blue Stripe

Temperature Switch to Warning Horn


Starter Solenoid to Starter Motor


Starter to Regulator (Charging Circuit)

Yellow/Red Stripe

Start Switch to Start Solenoid to Neutral Start Switch

Yellow/Black Stripe

Choke (Enrichener System)

Green with Color Stripe

Switch Box to Coil - Striped and Numbered

White/Black Stripe

Bias Circuit (Switch Boxes)


The current  ABYC Recommended Colors


Where Used / Function


Starting Circuits

Brown/Yellow or Yellow

Bilge Blowers

Dark Grey

Navigation Lights & Tach Signals


Accessory Feeds




Instrument Feeds

Dark Blue

Cabin and instrument Lights

Light Blue

Oil Pressure


Water Temperature


Fuel Gauge Sender



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