2003 LEXUS LS430 fuse

a. Check the resistance of the HORN fuse.
Standard: Below 1 ohms
If the result is not as specified, replace the fuse.
Fig. 4: Inspecting Fuse (Horn)

Courtesy of TOYOTA MOTOR SALES, U.S.A., INC.
2.INSPECT HIGH PITCHED HORN ASSY
a. Check operation of the horn.
OK:
HIGH PITCHED HORN ASSY TABLE
Measurement ConditionSpecified Condition
Battery positive (+) --> Terminal 1, Battery negative (-) --> Horn bracketHorn sounds

Fig. 14: Wiring Diagram - Driver Door ECU Power Source Circuit
Courtesy of TOYOTA MOTOR SALES, U.S.A., INC.
INSPECTION PROCEDURE
1.INSPECT FUSE (MPX-IG, AM1, D DOOR, MPX-B1, D/C CUT)
a. Remove the MPX-IG and AM1 fuses from the driver side J/B.
b. Remove the D DOOR and MPX-B1 fuses from the passenger side J/B.
c. Remove the D/C CUT fuse from the FL block assy.
d. Measure the resistance.

Standard: Below 1 ohms
NG: REPLACE FUSE
OK: GO TO NEXT STEP
2.INSPECT RELAY (Marking: D-IG1)
a. Remove the D-IG1 relay from the driver side J/B.
b. Measure the resistance.
Standard:
Fig. 15: Identifying terminals Of D
-IG1 Relay
Courtesy of TOYOTA MOTOR SALES, U.S.A., INC.
SPECIFIED CONDITION
NG: REPLACE RELAY
OK: GO TO NEXT STEP
Tester connectionSpecified condition
3 - 510 kohms or higher
3 - 5Below 1 ohms (when battery voltage is applied to terminals 1 and 2)