646 Datasheet, PDF (1/8 Pages) Littelfuse – MINIATURE FUSEHOLDERS

INSTALLATION INSTRUCTIONS
®
FORM 1008 (REV. A) 01/02
WINDOW RPM ACTIVATED SWITCH
PART NO. 646
Parts Included in this kit:
1 RPM Activated Switch Part No. 646
1 “U” shaped crimp-on wire terminal
1 #6 x 1/4" sheet metal screw
2 Velcro™ strips
CONTENTS
General Information ...................................................................... 1
Mounting Procedure ..................................................................... 1
Wiring Procedure .......................................................................... 1
How to Set the Window RPM Switch ........................................... 2
Wiring Diagrams for the RPM Activated Switch
Connecting to a HYFIRE^® IV ..................................................... 2
Connecting to a HYFIRE^® VII .................................................... 3
Connecting to relays with a HYFIRE^® VII ................................ 3
Connecting to a Timing Retard ................................................ 4
Connecting to a Timing Control ............................................... 4
Connecting to a Light ............................................................... 4
Connecting to an Electric (Shifter) Solenoid .......................... 5
Connecting to a Nitrous System .............................................. 6
Connecting to a Nitrous System and Timing Retard .............. 6
Shifnoid Warning ....................................................................... 7
GENERAL INFORMATION
The Mallory 646 Window RPM Switch is an RPM switch that is triggered
from the tach terminal available on most aftermarket performance ignitions.
It will not only activate at a particular RPM, but can also be set to de-
activate at a second, higher, RPM. It can be used on 4-12 cylinder engines.
WIRING PROCEDURE
Step 1
Connect the BLACK WIRE to engine or chassis ground. You can use the
supplied “U” shaped terminal and ^#6 x 1/4" sheet metal screws to make
this connection. If you are connecting the RPM Activated Switch to an
aftermarket ignition system such as a Mallory HYFIRE^®, use the same
grounding location that the ignition uses. See Figures 2-4, pages 2-3.
Step 2
Connect the RED WIRE to a 12-volt power supply, such as the ignition
switch. You can use the same wire that provides power for your ignition
as long as a ballast resistor is not wired in series with it. NOTE: Do NOT
connect the RED WIRE to the coil (+) terminal. Connect it to the
wire coming directly from the ignition switch. If your vehicle is
equipped with loom resistance wire, you must provide an alternate
power connection to the red wire.
Step 3
The GREEN WIRE must be connected to the ignition system tach output.
• When using a Mallory ignition system, connect the GREEN WIRE
to the TACH terminal. See Figures 2-4, pages 2 and 3.
• When using an aftermarket ignition with a TACH output, connect
the GREEN WIRE to the TACH terminal. Check manufacture’s ig-
nition instructions to find this location.
• Other aftermarket ignitions – Connect the GREEN WIRE to the ta-
chometer lead terminal. Check manufacturer’s ignition instructions
to find this location.
NOTE: The Mallory 646 CANNOT be triggered from points or elec-
tronic distributor. It must be triggered from a tach output terminal.
The 646 features two independent sets of switch contacts that switch other
devices on or off when the selected RPM is reached. These contacts
switch a maximum current of 5 amps. To switch more than 5 amps, you
must use the RPM Activated Switch output to drive a high current relay,
such as a horn or headlight (see illustrations).
NOTE: The switch contacts are NOT connected electrically. This
allows you to turn one circuit on and another off at the same RPM.
MOUNTING PROCEDURE
Step 1
Disconnect the battery (–) cable to cut power to the system.
Step 4
To connect a device that you want to switch ON at the RPM setting
you’ve selected, such as a shift light, connect one ORANGE WIRE to the
device and the other ORANGE WIRE to a 12-volt power supply. Connect
the remaining wire from the device to a ground. See Figure 5, page 4.
Step 5
To connect a device that you want to switch OFF at the RPM setting you’ve
selected, such as a nitrous solenoid, connect one PURPLE WIRE to the
device and the other PURPLE WIRE to a 12-volt power supply. Connect
the remaining wire from the device to a ground.
Step 6
Secure all wires to prevent contact with extreme heat, sharp objects, or
moving devices, such as fans, belts, and linkages.
Step 2
Mount the unit in an area away from hot engine components or extreme
heat, such as exhaust manifolds, and away from moving parts, such as fans,
belts, and linkages.
Step 3
Mount the unit using supplied Velcro™ strips.
Step 7
Recheck all wires and connections to ensure that they are correct before
applying power.
Step 8
Reconnect the battery (–) terminal cable. Start engine and check operation
of the RPM Activated Switch.
MALLORY TECHNICAL SUPPORT [phone] [e-mail]
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