Komatsu PC200-8M0, Shop Manual, Page: 712 / 1254

303 Troubleshooting by failure code, Part 3
Failure code [DB2QKR] CAN2 Discon (Engine Con)
40-303
36
PC200, 200LC, 220, 220LC-8M0
SEN06135-00
Failure code [DB2QKR] CAN2 Discon (Engine Con)
Action
level
Failure code
Failure
CAN 2 Disconnection Engine controller
(Detected by machine monitor) (Machine monitor system)
L03 DB2QKR
Detail of failure
q
Machine monitor cannot recognize engine controller through CAN communication 2 line (KOM-
NET/c).
Action of con-
troller
q
Holds information at the time of occurrence of failure.
Problem on
machine
q
Information to be obtained from engine controller is not displayed and special functions that use
them do not work. Or, received data is no longer updated. (such as failure codes and monitoring
codes sent from engine controller)
Related infor-
mation
q
Method of reproducing failure code: Turn starting switch to ON position.
q
Start of CAN communication is recognized by each controller when ACC signal of starting switch
is received.
q
Machine monitor indicates a CAN communication error in CAN2 with failure code [ DA2QKR ],
[ DB2QKR ], [ D8AQKR ], or [ DAZQKR ]. If all four of these failure code are displayed, harness (CAN
communication line) may have ground fault, short circuit, or hot short circuit. Since air conditioner
is also controlled via CAN communication, check whether air conditioner is operated (ON/OFF and
air flow adjustment) on air conditioner screen.
a
Air conditioner can be operated even when failure code is displayed on machine monitor screen. If
air conditioner is operated, there is no possibility of ground fault, short circuit, or hot short circuit in
wiring harness (CAN communication line).
q
Since each controller and machine monitor are connected to continuous power supply, they receive
continuous power even while starting switch is at OFF position.
q
Since active CAN communication line signal is pulse voltage, it cannot be measured by using mul-
timeter.
Cause Procedure, measuring location, criteria and remarks
1
Defective fuses Nos. No.19 (30 A)
for (engine controller) in fuse box
F01 1. Turn starting switch to OFF position.
2. Remove fuses No.19 (30 A) from fuse box F01.
q
When fuse is blown, engine controller may have short circuit in it.
2 Defective engine controller
a
If fuse is not blown, this check is not required.
1. Turn starting switch to OFF position.
2. Disconnect connector CE03, and connect T-adapters to male side.
Between CE03 (male) (3) and (1) Resistance Min. 10
z
3
Improper power supply to engine
controller
a
Check ground terminal T12 for looseness and rust.
1. Turn starting switch to OFF position.
2. Disconnect connector CE03, and connect T-adapters to female side.
3. Turn starting switch to ON position.
a
If result is abnormal, perform troubleshooting for [ CA441 ].
Between CE03 (female) (3) and (1) Voltage 20 to 30 V
4
Defective CAN terminating resis-
tor
(internal open or short circuit)
1. Turn starting switch to OFF position.
2. Disconnect connectors CM02 and K02, and connect T-adapters to each
male side.
Between K02 (male) (A) and (B) Resistance 120 ± 12
z
Between CM02 (male) (7) and (9) Resistance 120 ± 12
z