Parking Brake Is Applied While Machine Is Traveling - Komatsu WA900-3E0 Shop Manual

Troubleshooting of electrical system (E-mode),
E-4 Parking brake is applied while machine is traveling.
E-4 Parking brake is applied while machine is traveling.
Failure
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Related information
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No. Cause
1 Defective parking brake switch
Defective parking brake safety
2
relay L59
Defective parking brake emer-
3
gency release relay PL11
Defective emergency brake switch
4
(any of four switches)
5 Defective parking brake (solenoid)
40-62

Parking brake is applied while machine is traveling.

Parking brake is applied when voltage (24 V) is not applied to parking brake solenoid.
Since relay L59 is activated and PL12 is not activated during travel, voltage (24 V) is applied
between pin C of PL01 and pin 1 of F11 (when normal).
Parking brake may be released by using parking brake emergency release connector in fuse
box.
Output signal to parking brake interlock relay can be checked with monitoring function.
Code: 40990 "D-OUT-0" (ON: 1, OFF: 0)
1. Turn starting switch to OFF position.
2. Disconnect L01, turn on and off parking brake switch to perform trouble-
shooting.
Resistance
Replace parking brake safety relay L59 with relay. If failure symptom disap-
pears, parking brake safety relay is defective.
Replace parking brake emergency release relay PL11 with another relay. If fail-
ure symptom disappears, parking brake emergency releaserelay is defective.
1. Turn starting switch to OFF position.
2. Disconnect BC8, BC9, BC10, and BC11, then connect short connector to
each of above (in place of emergency brake switch).
3. Start engine to charge accumulator, and then perform troubleshooting.
If failure symptom disappears, emergency brake switch is defective.
1. Turn starting switch to OFF position.
2. Disconnect F11 and insert T-adapter.
3. Start engine and perform troubleshooting.
Voltage
Procedure, measuring location, criteria and remarks
ON Between PL01 (male) (A) and (B)
ON Between PL01 (male) (B) and (C)
OFF Between PL01 (male) (A) and (B)
OFF Between PL01 (male) (B) and (C)
Between F11 (1) and (2)
4 0 - 6 2
Max. 1 z
Min. 1 Mz
Min. 1 Mz
Max. 1 z
20 to 30 V
WA900-3E0