Honda GL1800 Service Manual page 645

LIGHTS/METERS/SWITCHES
2. Turn the ignition switch to "OFF" and remove
the seat (page 2-5).
Remove the two screws and remove the relay
box.
Remove the relay blocks from the relay box.
3. Exchange the headlight adjuster relay with the
other good one.
Start the engine, let it idle and operate the head-
light adjusting switch.
• If the headlight adjuster functions properly,
replace the headlight adjuster relay with a
new one.
• If the headlight adjuster does not function, go
to step 4.
4. Turn the ignition switch to "OFF" and remove
the headlight adjuster relay.
Check for continuity between the Blue/white wire
terminal of the relay connector and ground.
Start the engine and let it idle.
There should be no continuity.
• If there is no continuity, go to step 5.
• If there is continuity, check for:
– short circuit in the Blue/white wire between
– faulty diode (D17)
5. Stop the engine then turn the ignition switch to
"ON."
Measure the voltage between the Brown/red
wire terminal (+) of the relay connector and
ground (–).
There should be battery voltage.
• If there is battery voltage, the system is OK;
check
terminals.
• If there is no voltage, check for an open circuit
in the Brown/red wire between the headlight
adjuster relay and fuse box (No. 9 fuse).
20-12
the headlight adjuster relay and oil pres-
sure switch diode (D17)
for loose contacts
HEADLIGHT ADJUSTER
RELAY CONNECTOR
or corroded
ELAY BOX
EADLIG T ADJUSTER RELAY
lue/white
EADLIG T ADJUSTER
RELAY CONNECTOR
Brown/red