Garmin 400W Series, Instructions Manual

400W Series 

190-01226-14 Rev. 3 

Instructions for Continued Airworthiness Bell 407 

Page 15 of 26 

Problem Possible 

Cause 

Solution 

The 400W Series unit 
does not transmit. 



 The PTT input is not being pulled 

low. 



  Check that the PTT (mic key) input is 

pulled low for transmit. 



 No transmit power to the COM. 



  Make sure power input is connected to 

the COM 25-pin connector P4002 11 
and 12 and ground to P4002 21 and 22.



 The input voltage is too low. 



  Increase input supply voltage to 

>12VDC. (>24VDC for 430AW models) 

The sidetone level is 
too low or too high. 



 Wrong type of headsets, or level 

needs adjustment. 



  If necessary, adjust the sidetone level.  

Sidetone adjustment is found on the 
COM Setup page. 

OBS Resolver won’t 
calibrate. 



 Incompatible resolver or improper 

connection. 



  Check the resolver specifications and 

wiring. 

OBS indication on 
400W Series unit 
does not agree with 
OBS setting. 



 400W Series unit resolver input not 

calibrated correctly. 



 Resolver has not been calibrated. 



  Check wiring and calibration. 

400W Series unit is 
not receiving heading 
from compass system 
(ARINC 429 heading 
input used) 



 ARINC 429 input port speed not 

correct 



  Check ARINC 429 input port speed 

setting for port that device is connected 
to and verify that the speed is correct for 
that device. 



 Wiring connections are incorrect. 



 Check 

wiring. 

RMI pointer does not 
indicate correctly 



 Desired RMI source has not been 

selected. 



  Check the OBI source selection on the 

Main CDI/OBS Config page. 



 Wiring connections are incorrect. 



 Check 

wiring. 

Tuning data not 
updating DME 



 Incorrect configuration. 



  Check the DME Channel Mode on the 

VOR/LOC/GS CDI page. 



 Wiring connections are incorrect. 



 Check 

wiring. 

ARINC 429 device is 
not receiving data 
from the 
400W/420W/430W. 



 400W Series unit ARINC 429 

output not configured correctly. 



  Check ARINC 429 output port setting for 

port that device is connected to. 



 ARINC 429 input port speed not 

correct 



  Check ARINC 429 input port speed 

setting for port that device is connected 
to and verify that the speed is correct for 
that device. 



 Wiring connections are incorrect. 



 Check 

wiring.