Troubleshooting Information - Garmin 400W Series Manual

2.5.1 Cleaning the Front Panel
The front bezel, keypad, and display can be cleaned with a soft cotton cloth dampened with clean water.
DO NOT use any chemical-cleaning agents. Care should be taken to avoid scratching the surface of the
display.
2.5.2 Display Backlight
The display backlight lamp is rated by the manufacturer as having a usable life of 20,000 hours. This life
may be more or less than the rated time depending on the operating conditions of the 400W Series unit.
Over time, the backlight lamp may dim and the display may not perform as well in direct sunlight
conditions. The user must determine by observation when the display brightness is not suitable for its
intended use. Contact the Garmin factory repair station when the backlight lamp requires service.
2.5.3 Battery Replacement
The 400W series has an internal keep-alive battery that will last about 10 years. The battery is used for
GPS system information. Regular planned replacement is not necessary. The 400W series will display a
'low battery' message when replacement is required. Once the low battery message is displayed, the
battery should be replaced within 1 to 2 months.
If the battery is not replaced and becomes totally discharged, the 400W Series unit will remain fully
operational, but the GPS signal acquisition time may be increased. This acquisition time can be reduced
by entering a new seed position each time the unit is powered on. There is no loss of function or
accuracy of the 400W Series unit with a dead battery.
The battery must be replaced by the Garmin factory repair station or factory authorized repair station.

2.6 Troubleshooting Information

If error indications are displayed on the 400W series unit, consult the Troubleshooting section contained
below:
Problem
• The unit is not getting power to
The 400W Series
unit does not power
on.
• Not receiving signals.
The 400W Series
unit does not
compute a position.
400W Series
Instructions for Continued Airworthiness Bell 206B
Table 2 Troubleshooting Guide
Possible Cause
the main connector P4001.
Solution
• Make sure power is connected to the
main 78-pin connector P4001, pins
19 and 20 and ground to P4001, pins
77 and 78. Check circuit breakers
and main avionics switch.
• Check the GPS antenna connections.
Make sure the aircraft is clear of
hangars, buildings, trees, etc.
• Wait 20 minutes for unit to complete
cycle.
190-01226-04 Rev. 2
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