ISSPRO R6535M - Manual (Page 2)

Form No. IS016 (10/21/02 Rev. B) Page 2 of 5
drive ratio. Example: Cam drive of 0.5 revolutions per engine revolution and an R8970 give a calibration number of
15.
It is important to use a sensor that gives a whole calibration number. Fractions will make the tachometer inaccurate.
If it is not possible to determine the calibration number by any method described above, it is possible to use an
optical tachometer to get the actual RPM . Use the following method to set the tachometer:
New calibration number = switch setting number X Correct RPM reading
Indicated
tachometer reading
Setting the Tachometer:
Remove the switch access cover, located at the rear of the unit, by removing the two hold down screws. (See
illustration)
Locate the calibration number on the Calibration Chart to determine switch position. Example: For a 3500RPM
FSD (Full Scale Deflection) tachometer, a calibration number of 45 gives a switch setting of 2,3,4,5 and 8 ON. All
other switches are OFF.
Note that the switch setting will only be accepted when power is cycled from OFF to ON.
Replace the switch access cover and screws. Do not over tighten screws.
Installation:
Make all connections to the supplied plug before connecting to the tachometer. When mounting, the recommended
hole size is 3.32” diameter.
Connect the tachometer wiring as follows:
Red wire:
Battery positive. (Does not lose power with ignition OFF).
Black wire: Ground wire and one sensor wire.
Blue wire: Ignition voltage (Only has power when ignition switch is ON).
Green wire: Tach signal from sensor or alternator.
White wire: Dashboard illumination.
WARNING: Gauge has 12V light bulbs installed, 24V applications need to follow lamp replacement
instruction
Mount the tachometer into the dash panel.
Testing:
Confirm operation of the tachometer by starting the engine. When the ignition is “OFF” the pointer is free to move
to any position. When ignition is applied, the pointer will move to its appropriate position.
Lamp Replacement:
Remove the two rubber caps by pulling while gently rotating. Remove the lamp holders by rotating counter
clockwise. The lamp can be removed from the holder by pulling it.
Cylinder selection switch cap and
rubber cap removed condition.
Remove
these rubber
caps for lamp
Remove these screws for accessing
cylinder selection switch