MSD 8956 Installation Instructions

Rpm activated window switch

MSD RPM Activated Window Switch

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will help if there is ever a warranty issue with your product and helps the MSD R&D team create

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IMPORTANT: Read the instructions before attempting the installation.

Parts Included

1 - RPM Window Switch

4 - Self Tapping Screws

Note: RPM Modules must be purchased separately. See the chart on the last page for part

numbers.

The RPM Activated Window Switch can be connected to stock ignition systems or MSD Ignitions. When

using a capacitive discharge ignition such as an MSD, do not connect the Switch to the coil negative

terminal. Damage to the Switch may occur.

The Switch is capable of carrying 1.5 amps. If the circuit you are activating requires more current, an

MSD Relay, PN 8960 or 8961 must be used. The MSD RPM Activated Switch is equipped with a "smart

driver". This circuit will protect the RPM Switch from damage by monitoring its temperature. If there is an

inadvertant short or too much current is drawn through the Switch, the smart driver will sense the increased

temperature and shut the Switch off. However, once the temperature drops to a safe point, the smart driver

will turn the Switch back on. It will continuously cycle On and Off as the temperature dictates.

If you experience a problem with your Switch not operating, turn the circuit off for a few minutes to cool, then try

again. If the circuit activates then shuts off, there may be too much current flow. Check the device's Installation

Instructions to find its recommended maximum current.

The RPM Window Switch has a circuit that activates a device by providing a ground path at a desired

rpm (Figure 1). The ground will be removed at a different rpm to deactivate the device. If no rpm

module is installed, the device will remain activated as long as the rpm is above the activation amount.

M S D

• W W W . M S D P E R F O R M A N C E . C O M • ( 9 1 5 ) 8 5 7 - 5 2 0 0 • F A X ( 9 1 5 ) 8 5 7 - 3 3 4 4

PN 8956

4 - Heat-Shrink Caps

Figure 1 Operation of the RPM Window Switch.

Table of Contents

Do you have a question about the 8956 and is the answer not in the manual?

Page 1 PN 8956 ONLINE PRODUCT REGISTRATION: Register your MSD product online. Registering your product will help if there is ever a warranty issue with your product and helps the MSD R&D team create new products that you ask for! Go to www.msdperformance.com/registration.
Page 2: Installation Instructions
Black Connects to ground. White The rpm input wire. With an MSD Ignition, this connects to the Tach Output terminal. On inductive ignitions, it connects to the coil negative terminal. Yellow This is the circuit ground wire (normally open switch to ground). It connects to the ground side of the device you plan to activate.
Page 3 INSTALLATION INSTRUCTIONS Note: Capacitive discharge ignitions only. Figure 4 Wiring to an MSD Ignition Control. Figure 5 Wiring with an MSD Relay. M S D • W W W . M S D P E R F O R M A N C E . C O M • ( 9 1 5 ) 8 5 7 - 5 2 0 0 • F A X ( 9 1 5 ) 8 5 7 - 3 3 4 4...
Page 4: Limited Warranty
*Intended normal use means that this item is being used as was originally intended and for the original application as sold by MSD. Any modifications to this item or if it is used on an application other than what MSD markets the product, the warranty will be void.