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OPERATING INSTRUCTIONS

®

PART NO. 676M

FORM 1554M (REV. A) 10/02

RPM Switch:

built-in RPM switch can either turn an electrical load off or on

at a selected RPM. See below for more detail.

NC

This is the RPM switch (mode 7) relay contact that is

normally closed. In other words, as long as you haven’t

reached the point where the RPM switch is active, this

contact remains connected to the “common” or “C” ter-

minal. You would use this connection if, for example,

you wanted to turn something OFF (such as a nitrous

system) when you reached the RPM switch point. See

Example 1.

C

This is the common terminal for the RPM switch (mode

7) relay in the main unit. It is connected to the RPM

switch, where it will switch the accessory connected to

the “NC” terminal OFF, and the accessory connected

to the “NO” terminal ON when the RPM switch value is

reached. The “C” terminal can be used to switch either

to power or ground.

NO

This is the RPM switch (mode 7) relay contact that is

normally open. In other words, as long as you haven’t

reached the point where the RPM switch is active, this

contact isn’t connected to the “C” contact. You would

use this contact to turn something ON (such as a shift

light or an air shifter) at a specific RPM. See Example 2

and Example 3.

RPM Limiters:

one has a range of 1000 to 12,800 RPM in 50 RPM steps. On the

main display, there is a decimal point on the mode digit. When that

decimal point is lit up, the RPM limit is increased by 50 RPM.

RPM1 (Mode 1)This is the RPM limit that is always active if you

haven’t selected any other RPM limit.

RPM2 (Mode 2) This is an auxiliary RPM limiter that is acti-

vated when you apply 12 volts to the “RPM2” terminal on

the top-side connector. This could be a burnout limiter.

When selected, it overrides RPM 1 (the main engine

protection RPM limiter). See Example 4.

RPM3 (Mode 3) This is the other auxiliary RPM limiter. It also

is activated by 12 volts on the “RPM3” terminal on the

top-side connector, and overrides both RPM2 and

RPM1. Use this limit as a staging (starting line) RPM

limiter. See Example 5.

High Speed Timing Retards:

RET1, RET2, RET3 (Modes 4, 5, 6) These are all high-speed

timing retard functions that are activated by 12 volts on the appro-

priate top-side connector terminal. Each higher stage overrides

the lower stages, which means that you set each stage for exactly

the amount of retard you want, rather than adding up each stage to

get the actual retard. See Example 6.

NOTE: When you apply 12 volts to RPM2, RPM3, RET1, RET2,

or RET3 the display will switch to show that function. If you

have both an auxiliary RPM limit AND a retard selected, the

display will show the retard value.

See the accompanying illustrations for some examples of how to use

the RPM limiters, the RPM switch, and the timing retard functions.