Electrical System | Mercruiser Engine

Compatible Applications

The following applications are taken from the supplied Mercury fitment information. Because this switch is used across multiple engine and shift systems, serial number is important.

Mercury / Mariner 3.0L Outboards

Mercury 3.0L DFI / Pro XS / Sport XS Applications

Mercury Racing / Special Performance Applications

Mercury V6 2.5L Applications

Mercury Verado Applications

Mercury 75-115 HP EFI Applications

MerCruiser Sterndrive Applications

The supplied Mercury fitment also shows this switch in multiple MerCruiser Digital Throttle and Shift shift-bracket and actuator assemblies.

Mercury Diesel / CMD Applications

OEM and Cross Reference Numbers

OEM Mercury Version Available

Mercury OEM Switch - 8M0052939

Prefer the genuine Mercury version? Pro Marine USA also stocks the OEM Mercury switch for this application.

View Mercury OEM 8M0052939 Switch

What This Part is Used For

The neutral safety / shift position switch provides the engine or control system with information about the position of the shift mechanism.

In applications where it functions as the neutral safety switch, it is part of the starting-safety circuit designed to prevent the engine from being started when the shift mechanism is in gear.

Mercury also uses this switch within several mechanical and Digital Throttle and Shift (DTS) systems, which explains the wide variety of outboard, sterndrive and inboard applications shown in the fitment data.

Common Symptoms of a Faulty Neutral Safety / Shift Switch

• Engine will not crank even though the control is in neutral
• Intermittent no-crank condition
• Starting issue changes when the control lever is moved slightly
• Incorrect or inconsistent shift-position signal
• DTS or shift-related fault after other causes have been ruled out
• Physical damage to the switch or actuator
• Corrosion or damaged electrical connections

These symptoms can also be caused by wiring, adjustment, control or starting-system problems. Diagnose the system before replacing the switch.

Installation and Replacement Tips

• Disconnect battery power before servicing the shift or starting circuit.
• Confirm the OEM switch number before removing the original part.
• Note the position and adjustment of the original switch before removal.
• Inspect the switch connector and wiring for corrosion or damage.
• Check the shift linkage for excessive wear or improper adjustment.
• Install and adjust the switch according to the applicable Mercury service procedure.
• Verify that the engine starts only in the intended neutral position where applicable.
• Verify proper forward, neutral and reverse operation after installation.
• On DTS applications, follow the appropriate Mercury diagnostic and setup procedures.

Key Features and Benefits

• Pro Marine aftermarket replacement switch
• Fits numerous Mercury Marine shift-system applications
• Applications include Mercury and Mariner outboards
• Fits select Mercury Verado and Pro Verado models
• Fits select Mercury Pro XS, XS and racing outboards
• Fits select MerCruiser sterndrive applications
• Fits select MerCruiser inboard and TowSports applications
• Used in mechanical and DTS-related shift systems depending on application
• Crosses to Mercury 8M0207794
• Crosses to Mercury 8M0052939
• Crosses to 889514A01, 814281A7 and 879150T94
• Pro Marine item number 52939P

FAQ

What does Pro Marine 52939P fit?
It fits a wide range of select Mercury Marine applications including Mercury and Mariner outboards, Verado, Pro XS and racing outboards, plus numerous MerCruiser sterndrive, inboard and TowSports applications. Use the model and serial-number tables above for fitment.

Is 52939P a neutral safety switch?
Yes. It is commonly identified as a neutral safety / shift position switch. Its exact role varies with the Mercury shift system in which it is installed.

Does 52939P replace Mercury 8M0207794?
Yes. 8M0207794 is the current Mercury reference associated with this switch application.

What happened to Mercury 8M0052939?
Mercury parts data shows 8M0052939 superseded by 8M0207794.

Does this replace 889514A01?
Yes. 889514A01 is an earlier Mercury switch assembly in the verified supersession family.

Does this replace 814281A7?
Yes. 814281A7 is also an earlier Mercury switch number in the verified supersession family.

Does it fit Mercury Verado?
Yes. The supplied Mercury fitment includes numerous 135-350 HP Verado applications, including 4-cylinder, 6-cylinder and Pro Verado models. Serial number must be verified.

Does it fit Mercury Pro XS?
Yes. The supplied fitment includes several Pro XS applications, including 2.5L and 3.0L models. Refer to the model and serial ranges above.

Does it fit MerCruiser engines?
Yes. The supplied Mercury fitment includes numerous MerCruiser sterndrive and inboard applications, including 496 MAG, 5.0L MPI, 350 MAG, 377 MAG, 8.2L and several CMD / TDI diesel applications.

Can I select this switch by horsepower?
No. This switch spans many engine families and shift systems. Verify the engine model, serial number and OEM part number before ordering.

Do you also carry the genuine Mercury switch?
Yes. Pro Marine USA also stocks the Mercury OEM 8M0052939 switch .

Searchable Part Numbers

52939P, 8M0207794, 8M0052939, 889514A01, 814281A7, 879150T94

Searchable Terms

Mercury neutral safety switch, Mercury shift switch, Mercury shift position switch, Mercury neutral switch, Mercury outboard neutral safety switch, Mercury Pro XS shift switch, Mercury Verado shift switch, Verado neutral safety switch, Mercury 3.0L shift switch, Mercury DTS shift switch, MerCruiser neutral safety switch, MerCruiser shift switch, MerCruiser DTS switch, 8M0207794 switch, 8M0052939 switch, Pro Marine 52939P