Shift Interrupter Switches
Pre-Alpha, Alpha One and Alpha Gen II engines use a Shift Interrupter Switch.
This switch allows the drive to shift back into neutral with less effort.
If the switch is defective or disconnected it will be very difficult to get neutral.
If the shift cable is bad, it can cause the switch to "over-activate" and stall the engine when you shift.
The older original switches used a metal fulcrum lever with a roller on the end.
These switches are no longer in production.
These older switches can no longer be purchased.
Instead, you must order a complete Shift Plate Mechanism.
The new shift plate mechanism uses an improved switch design.
Mercruiser has the buyer refer to Bulletin MCM 02-01 for the correct shift plate mechanism.
The new switch does not have a metal fulcrum lever or roller.
The new switch will not fit the old mounting plate.
Mercruiser sells complete Shift Plate Assemblies to replace the old switch and plate.
Shift Interrupt Switch Availability
NOTE: 1.
For the following models that have the Shift Interrupt Switch mounted to the top of the
aluminum rocker cover, an alternate location will have to be selected for mounting the
replacement Shift Plate Kit.
MCM 120/140 S/N 6229718 thru 0C856558
MCM 3.0L/LX (Conventional / DIG.IGN. / EST IGN.) 0C856559 thru 0F603999
MCM 3.0LX 0F604000 thru 0K999999
NOTE: 2.
The models listed following have the Shift Interrupt Switch mounted either on the Transom
Plate or on a shift plate assembly attached at the top of the inner transom plate, with the
hydraulic reverse lock valve assembly. An alternate location will have to be selected for
mounting the replacement Shift Plate Kit.
Also a new trim pump will be required updating from the old Prestolite trim pump to the new
high pressure low flow Oil Dyne trim pump, part number 93247A 7. The new trim pump has
the reverse lock valve in the pump and will replace both the pump and the reverse lock valve
assembly, for replacement of the trim pump follow the instructions that come with the new
trim pump.
Order Now: Part 864363A1 Shift Interrupter Switch Plate Kit $171.00
Part 864364A1 Shift Interrupter Switch Plate Kit $151.00
