digi-tech AA-0375 User manual

User Manual
Versatile Automotive
LED Display Module
for Cars
AA-0375
Distributed by:
TechBrands by Electus Distribution Pty. Ltd.
320 Victoria Rd, Rydalmere
NSW 2116 Australia
Ph: 1300 738 555
Int’l: [phone]
Fax: [phone]
www.techbrands.com

Technical Specifications:
•Power: 12VDC
•Dimensions: 81(L) x 52(W) x 21(H) mm
Instructions:
•Connect the module according to the wiring diagram
depending on your use of the module. Incorrect wiring
will damage the module and your vehicle if you
connect it in the incorrect polarity:
oThree connections should be made to your car,
(1) +12V (ignition switched); (2) chassis (0V); and
(3) sensor or car battery signal. The car battery
signal is best taken at a point close to the battery
for accuracy.
oUse the car’s wiring diagram to find these
connections, and then use a multimeter to check
that they’re correct (e.g. check that the +12V
supply switches off when you turn off the
ignition).
oConfirm that there is a fluctuating signal in the 0-
1V range on the oxygen sensor lead (the car will
need to be fully warmed up) or that the signal
coming from the airflow meter, or MAP sensor
changes when the throttle is blipped. NOTE: The
0V connection for the Voltage Display should be
made at the ECU or to a terminal that is directly
to a chassis point.

•The red LEDs are the lowest voltage, and the yellow
LEDs are the highest voltage. Adjust the trimpot to suit
the voltage reading for your application.
•A Light Dependent Resistor (LDR) can be connected to
the unit for the LEDs to adjust their brightness
according to the ambient light. Use the trimpot to
adjust the dimming.
Setting up for an Oxygen Sensor:
Links LK1 and LK2 should be out and link LK4 should be
installed.
-Set the trimpot VR1 fully clockwise and trimpot VR2
fully anticlockwise.
-Start the car, let the oxygen sensor warm up and
confirm that the LED display changes.
-Go for a drive and briefly use full throttle. The end
yellow LED should light up. Back off sharply – the end
red LED should light.
-Check that the LEDs travel back and forth when the
engine is at idle.
-If the end yellow LED never lights, even at full throttle,
adjust VR1 so that it lights when the mixtures are fully
rich.
-During normal driving, the LED should move back and
forth around the centre LED. If the oscillations are all
down one end after adjusting VR1, adjust VR2 to centre
the display.

Setting up for a 0-5V Airflow Sensor:
Link LK2 should be installed and LK4 out.
-Use a multimeter to measure the battery voltage. Now
with the engine running fast and with all accessories off,
etc. lights, set VR1 so that the top green LED lights at a
measured 14.4V.
-Now stop the engine and switch on the lights. Wait until
the battery falls to a measured 12V and set VR2 so that
the lower green LED lights up.
-Again, the adjustments will affect one another to a
small extent so you may need to recheck the results at
either end of the scale.
Calibrating for Fuel Mixture Display:
•The easiest way of calibrating the module is on the
road, but is not appropriate for a car that is heavily
modified. For a modified car, use a chassis dyno.
•A low voltage reading from your car indicates that
your mixture is too lean. A high voltage shows that it is
too rich.
•Calibrating on the road: with an assistant in the
passenger seat and with the engine up to operating
temperature, drive at a constant speed with a steady
throttle opening. The lit LED should start oscillating up
and down the display, as the ECM makes the mixtures
alternatively rich and lean in closed loop operation.
Adjust the trimpot VR1 so that the oscillations in either

direction are symmetrical around the middle LED. It is
now ready for use.
NOTE: At idle, the mixture display should again show
the closed loop oscillations.
•Calibrating on a car that is heavily modified: in-car
calibration can still be done with the proviso that the
mixtures may be all wrong to start with. The safest
approach is to use a chassis dyno and an exhaust gas
analyzer so that the mixture display can be calibrated
according to the gas analyser’s readout.
•
LEDs can also be attached to the module with fly
leads if you would like to integrate it into your
vehicle’s dashboard.
Notes:
•Never get any part of the module wet.
•Never attempt to open, modify or repair any part of the
module.

Wiring Diagram: