ISSPRO R8588M - Manual (Page 2)

Form IS128 (Rev C 12/02/2010) Page 2 of 4
ALTERNATOR TAP INPUT: If a tap from the alternator has been provided, it can be used to provide the input signal.
# PULSES PER REV = Number of Poles on Alternator X Diameter of Crank Pulley
2 Diameter of Alternator Pulley
INSTALLATION: Mount the tachometer in the dash panel and connect the wires as described below:
Make all of your connections to the Black plug supplied and then
plug it in to the tachometer's white connector.
Magnetic Sensor & signal Generator Applications Alternator Tap Application
Connect to ignition switched power source  Red  Connect to ignition switched power source
Connect to ground along with one of the sensor wires  Black  Connect to ground
Connect to other sensor wire  White  No connection
Connect to dash lamp power  Green  Connect to dash lamp power
Optional – se note 5  Violet  Connect to alternator tap
INSTALLATION HINTS:
1) Magnetic sensors only: Bring both sensor wires back to the connector. Don’t connect the sensor ground wire to a point which is
physically different from the tachometer ground.
2) When power is applies, the needle should go to mid scale, then to the zero position. If it does not, there may be a bad connection in
the “hot” (red) wire, or in the ground wire circuit. Check power to the meter by measuring with a voltmeter at the plug (meter leads
on the pins that attach to the red and black wires). If there is power at the plug, the problem is in the gauge.
3) Low voltage (below 10.5 volts) will cause an inaccurate reading. Determine accuracy by comparing the reading with a phototach. If
a problem exists, measure voltage with vehicle operating and meter connected. This can be done by connecting a voltmeter to a
power source (i.e. fuse block, etc) and /or by connecting the voltmeter leads to the red and black wires where they enter the tach’s
white connector.
4) Magnetic sensors only: If the tach reads zero, then “jumps” to a normal reading after a repeatable RPM, adjust the sensor so that it is
closer to the gear (generators cannot be adjusted).
5) If the tach operates erratically, disconnect signal wire from the white input wire and connect it to the violet input wire. The violet
input has additional electrical noise filtering.
Common Applications Microprocessor Tachometer Calibration
The following table may be useful in calibrating the ISSPRO programmable tachometers in some ring gear sensing installations.
This information is believed to be accurate, however, exceptions will occur and it is always best to verify the number of gear teeth
when in doubt.
ENGINE # RING GEAR TEETH SWITCHES SET “ON”
CUMMINS: L10 103 1,2,3,6,7
475, K6 118 2,3,5,6,7
*NTC. FORMULAS ( 855 series) 103 1,2,3,6,7
*Some models of cabover Freightliners use SAE #1 flywheels and have 118 ring gear teeth.
CAT: 3208 134 2,3,8
3306 156 3,4,5,8
3406, 3408 113 1,5,6,7
DDA-DETROIT: 8V71, 8V92, 6-71, 12-71, 6V-92 118 2,3,5,6,7
4-53 138 2,4,8
MACK: ALL (domestic) 118 2,3,5,6,7
GM: 8.2 liter – SAE #2 flywheel 138 2,4,8
(4 ¾” bolt centers on flywheel housing)
8.2 liter – SAE #3 flywheel 126 2,3,4,5,6,7
(4 ⅜” bolt centers on flywheel housing)