MAN# 650530:A
2
ALTERNATOR TACH INTERFACE UNIT
SET
:
ALT
For using a standard 4-6-8 cylinder tachometer on a diesel engine, the DSL-1 E can convert a
signal from the ‘W’ terminal on an alternator and convert it into a tachometer signal for a standard gas
ignition system tachometer. Not all alternators have a ‘W’ terminal. The unit is adjustable to allow
for the different numbers of poles on the alternator as well as different pulley sizes on the engine and
alternator. Calibration should be done using a light tach or another known reference for engine speed.
The DSL-1 E has an adjustable range of 4.00 to 0.250. Calibration can be set using the setup
mode and display or adjusted in real time while the engine is running. Wiring instructions are provided
below.
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DSL-1 E
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12V Accessory Power
GROUND
Sensor ground (not used)
Alternator 'W' terminal
standard tach output
1/2 rate tach output
high voltage tach output
jumper to HI VOLT output for some
early Toyota tachometers
Determining required calibration ratio.
It is easiest to begin with the CAL ratio set to 1.00. The new calibration ratio to make the tach
read correctly is found using the equation below.
(Actual RPM)
÷
(Tachometer reading) = calibration ratio
Calibration
Adjust with engine running: To increase the tachometer reading, press and hold the
+ push button switch. To decrease the tachometer reading, press and hold the - push button
switch.
Preset or adjust: The calibration value can be set from 0.250 – 4.00.
1. Begin with the key off.
2. Press and hold the SET switch while turning the key on. The display will show the current
version code.
3. Release the SET switch. The display will show “
SEt
”.
4. Press and release the INC switch until “
ALt
” is displayed, then press and release the SET
switch.
5. The display will show the ones digit of the currently stored calibration value. Press and
release the INC switch to set this from 0. - 4. for your desired calibration value.
6. Once finished Press the SET switch to move to the tenths digit. Press and release the INC
switch until your desired value is shown.
7. Press the SET switch to move to the hundredths digit. Press and release the INC switch
until your desired value is shown.
8. Press the SET switch to save the hundredths digit. If the value is 1.00 or higher the
calibration value will be saved. The calibration set is done.
9. If the value is 0.99 or lower the thousands digit will now be set. Press and release the INC
switch until the desired value is shown. Press the SET switch to save and finish.
10. The display should now show the next menu option, “
SIG
”. Turn the key off.
