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Procedure 5-7
Starting up the ECU
Use this procedure to verify the environmental control unit (ECU) start up
sequence. The ECU has a start up and initialization routine which begins if any
of the following three procedures are performed:
•
•
•
During start up, the processor begins an initialization procedure to control all
ECU functions (see
Action
Step
1
2
3
4
5
6
7
8
The reset switch is pressed, which is located next to the heat exchanger
(HX) fan 1 LED on the front panel. This will cause a restart.
The software locks up and the watchdog timer (WDT) times out and forces
a reset and a restart.
When power is first applied, the power on reset causes a reset and start up
begins.
Figure
Action
Check that the following start up occurs in sequence.
Check that all LEDs will first light red.
Check that all LEDs will light green.
Check that all LEDs will turn off.
Check that all LEDs will cycle one at a time to indicate individual control.
Check that all LEDs will light in a chasing sequence, first green and then red.
Check the LED array will display a green led to indicate an on dip switch.
Check the LED array will not light to indicate an off dip switch.
Note 1: While the ECU is displaying the dip switch sequence, all fans that are
enabled will cycle on and off.
Note 2: After all fans are turned off, the ECU will enter the main control loop
and begin operating based on temperature.
5-12) and steps below.
—end—
User Guide
Maintenance 5-17
Rel 1.0 Standard May 1999
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