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OPERATING INSTRUCTIONS

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PART NO. 674

RPM Switch:

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” terminal. 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 acces-

sory 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:

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 activated 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 (start-

ing 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 appropriate 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.

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FIGURE 1

Push this button to change the mode.

Push either of these buttons to change

the value of the mode.

NOTE: If any button is held down for more

than 1/2 second, the displayed value will

change automatically.

FORM #1492 (REV. B) 9/00