Horn Does Not Sound Or Does Not Stop - Komatsu PC200-8M0 Shop Manual

SEN06138-00
E-24 Horn does not sound or does not stop
Failure 1) Horn does not sound.
Related infor-
mation
Cause
1 Defective fuse F01-5
Defective horn relay
2
(internal open or short circuit)
Defective horn switch
3
(internal open or short circuit)
Defective high-tone horn (M07)
4 or low-tone horn (M08) (internal
open or short circuit)
5 Defective wiring harness
Open circuit in wiring harness
6 (Wire breakage or defective con-
tact)
Ground fault in wiring harness
7
(contact with ground circuit)
46
40-400
Procedure, measuring location, criteria and remarks
If fuse F01(5) is broken, circuit probably has ground fault. In this case, perform
troubleshooting for cause 7 first.
1. Turn starting switch to OFF position.
2. Replace horn relay (connector: R08) with another relay.
3. Turn starting switch to ON position.
4. Press L.H. knob switch.
If horn sounds, original horn relay is defective.
1. Turn starting switch to OFF position.
2. Disconnect connector S10 and connect T-adapters to male side.
Between S10 (male) (1)
and (2)
1. Turn starting switch to OFF position.
2. Disconnect connectors M07 and M08, and connect T-adapters to each male
side.
Between M07 (male) (1) and (2)
Between M08 (male) (1) and (2)
1. Turn starting switch to OFF position.
2. Disconnect connector R08 and connect T-adapters to female side.
3. Turn starting switch to ON position.
4. Press L.H. knob switch.
Between R08 (female) (1) and (2)
Between R08 (female) (3) and (2)
1. Turn starting switch to OFF position.
2. Disconnect connector R08 and connect T-adapters to female side.
Between R08 (female) (5) and ground
Between R08 (female) (1) and ground
a If no failure is found by above checks, this check is not required.
1. Turn starting switch to OFF position.
2. Remove fuse F01-5.
3. Disconnect connectors R08 and S10, and connect T-adapters to each female
side.
Between F01-5 and S10 (female) (1)
Between S10 (female) (2) and R08 (female) (1)
Between R08 (female) (2) and ground
Between R08 (female) (3) and F01(5)
a If fuse is not blown, this check is not required.
1. Turn starting switch to OFF position.
2. Remove fuse F01-5.
3. Disconnect connectors R08, M07, and M08, and connect T-adapters to
female side of R08.
Between R08 (female) (1) and ground
Between R08 (female) (3) and ground
Between R08 (female) (5) and ground
400 Troubleshooting of electrical system (E-mode)
E-24 Horn does not sound or does not stop
Switch: OFF Resistance
Switch: ON Resistance
Resistance
Resistance
Resistance
Resistance
Resistance
Resistance
Resistance
PC200, 200LC, 220, 220LC-8M0
Min. 1 Mz
Max. 1 z
Continuity
Continuity
Voltage 20 to 30 V
Voltage 20 to 30 V
Continuity
Continuity
Max. 1 z
Max. 1 z
Max. 1 z
Max. 1 z
Min. 1 Mz
Min. 1 Mz
Min. 1 Mz