E-12 Brake Lamp Does Not Light Or It Keeps Lighting Up - Komatsu WA250-6 Shop Manual

SEN03848-00

E-12 Brake lamp does not light or it keeps lighting up

Contents of
Brake lamp does not light or it keeps lighting up.
trouble
Related
• The lamp or wiring harness of the brake lamp system is abnormal.
information
1 Broken bulb
Defective fuse No.11 of fuse
2
box (FS1)
Defective brake lamp relay
3
(L121) (Internal trouble)
Defective brake lamp switch
4
(Internal trouble)
Possible
causes and
standard value
in normal state
Disconnection in wiring har-
ness
5
(Disconnection or defective
contact in connector)
Ground fault in wiring harness
6
(Contact with ground circuit)
58
40-400
Causes
If a specific brake lamp does not light up, its bulb may be broken or
may have a defective contact. Check the bulb directly.
If the fuse is burn, the circuit probably has a grounding fault, etc.
(See cause 6.)
a Prepare with starting switch OFF, then carry out troubleshooting
without turning starting switch ON.
a Prepare with starting switch OFF, then turn starting switch ON
and carry out troubleshooting.
When brake lamp relay (L121) is replaced with a relay of the same
type, if the condition becomes normal, the brake lamp relay is defec-
tive.
a Prepare with starting switch OFF, then turn starting switch to
START and carry out troubleshooting.
Between (1) and (2)
Between (1), (2) and
a Prepare with starting switch OFF, then carry out troubleshooting
without turning starting switch ON.
Wiring harness between fuse No. 11 of fuse
box (FS1) – L121 (female) (3), – L34
(female) (1)
Wiring harness between L34 (female) (2) –
L121 (female) (1)
Wiring harness between L121 (female) (2) –
ground
Wiring harness between L121 (female) (5) –
R22 (female) (5), R23 (female) (5)
Wiring harness between R22 (female) (4),
R23 (female) (4) – ground
a Prepare with starting switch OFF, then carry out troubleshooting
without turning starting switch ON.
Wiring harness between fuse No. 11 of fuse
box (FS1) – L121 (female) (3), – L34
(female) (1), – circuit branch end and ground
Wiring harness between L34 (female) (2) –
L121 (female) (1) and ground
Wiring harness between L121 (female) (5) –
R22 (female) (5), – R23 (female) (5) and
ground
400 Troubleshooting of electrical system (E-mode)
E-12 Brake lamp does not light or it keeps lighting up
Standard value in normal state/Remarks on troubleshooting
L121 (male)
Between (1) and (2)
L34 (male) Brake pedal
ground
Resistance
200 – 400 z
Resistance
Press Max. 1 z
Released Min. 1 Mz
Constant Min. 1 Mz
Resis-
tance
Resis-
tance
Resis-
tance
Resis-
tance
Resis-
tance
Resis-
tance
Resis-
tance
Resis-
tance
WA250, 250PZ-6
1
Max. 1 z
Max. 1 z
Max. 1 z
Max. 1 z
Max. 1 z
Min. 1 Mz
Min. 1 Mz
Min. 1 Mz