Garmin 155XL Maintenance Manual - page 21

3-6

                          190-00067-25 Rev D

3.5

TROUBLESHOOTING

Table 3-2 contains problem/action information to aid in troubleshooting the GPS 155XL  Perform the actions in

the sequence they are listed.

Table 3-2. Troubleshooting Chart

PROBLEM

ACTION

Unit will not power on

Check External Power Connection

Check Remote External Battery Pack (if equipped)

Check Power Switch

Replace Power Switch (see section 4.3.7)

Replace CPU Board (see section 4.3.5)

Unit will not power off

Replace CPU Board (see section 4.3.5)

Replace Power Switch (see section 4.3.7)

Display has horizontal or vertical lines

Replace Display Module (see section 4.3.9)

Replace CPU Board (see section 4.3.5)

Display has missing or dark pixels

Replace Display Module (see section 4.3.9)

Display brightness not adjustable

manually

Replace CPU Board (see section 4.3.5)

Replace Control/Display Unit (see section 4.3.2)

Display brightness not adjustable via

photocell

Replace Control/Display Unit (see section 4.3.2)

Replace CPU Board (see section 4.3.5)

Keycaps have no backlighting

Replace Control/Display Unit (see section 4.3.2)

Replace CPU Board (see section 4.3.5)

Keycap backlighting not uniform

Replace Control/Display Unit (see section 4.3.2)

Bezel Annunciators do not function

Replace Control/Display Unit (see section 4.3.2)

Replace CPU Board (see section 4.3.5)

No external annunciator output(s)

(message, arrival)

Check connections and verify operation in Test

Mode

Replace CPU Board (see section 4.3.5)

Keycaps do not function properly

Replace Control/Display Unit (see section 4.3.2)

Replace CPU Board (see section 4.3.5)

Dual concentric (rotary) knobs do not

function properly

Check Flex Circuit connection from rotary switch to

back of Control/Display Unit

Replace Rotary Switch Assembly (see section 4.3.8)

Replace Display Module (see section 4.3.9)

Replace CPU Board (see section 4.3.5)