Komatsu PC200-8M0, Shop Manual, Page: 836 / 1254

400 Troubleshooting of electrical system (E-mode)
E-2 Preheater does not operate
40-400
14
PC200, 200LC, 220, 220LC-8M0
SEN06138-00
Cause Procedure, measuring location, criteria and remarks
8
Ground fault in wiring harness
(contact with ground circuit)
a
If no failure is found by check on cause 3, this check is not required.
1. Turn starting switch to OFF position.
2. Disconnect connectors H15 and CM01, terminals R15 and E01, and
starting motor terminal B.
Between heater relay terminal R15 (wiring harness
side) and ground
Resistance Min. 1 M
z
Between input terminal on contact side of heater
relay and ground
Resistance Min. 1 M
z
Between heater relay terminal E01 (wiring harness
side) and ground
Resistance Min. 1 M
z
Failure 2) Automatic preheating does not function.
Related informa-
tion
q
Automatic preheating starts when boost temperature is below -4 °C.
(Monitoring code Boost temperature: 18500)
q
If automatic preheating does not function, check if manual preheating functions.
q
Engine controller checks primary (coil) side of preheater relay (connector R18) and generates fail-
ure codes [
CA2555 ] and [ CA2556 ] if it is defective.
q
Engine controller checks boost temperature sensor and generates failure codes [ CA153 ] and
[ CA154 ] if it is defective.
Cause Procedure, measuring location, criteria and remarks
1
Defective fuse No. 6 in fuse
box F01 If fuse No. 6 in fuse box 01 is broken, circuit probably has ground fault. In this case,
perform troubleshooting for cause 5 first.
2
Defective auto preheater
relay R18 (open or short cir-
cuit in internal wiring)
1. Turn starting switch to OFF position.
2. Replace auto preheater relay (connector R18) with horn relay (connector R08),
for example.
3. Turn starting switch to ON position.
If automatic preheater operates when charged (boosted) air temperature is below
-4 °C, original auto preheater relay is defective.
3
Open circuit or ground fault in
wiring harness
1. Turn starting switch to OFF position.
2. Disconnect connectors CM01 and R18, and connect T-adapter to female side of
R18.
a
If resistance is above 1 M
z
, wiring harness has open circuit. If resistance is be-
low 1
z
, wiring harness has short circuit.
a
Heater relay coil resistance
Between R18 (female) (5) and ground Resistance Approx. 20
z
4
Open circuit in wiring har-
ness
(Wire breakage or defective
contact)
1. Turn starting switch to OFF position.
2. Disconnect connectors R18 and CM01, and connect T-adapters to female side
of R18.
3. Remove fuse No. 6 in fuse box F01.
Between R18 (female) (3) and F01-6 Resistance Max. 1
z
Between R18 (female) (5) and heater relay terminal
R15
Resistance Max. 1
z
5
Ground fault in wiring har-
ness
(contact with ground circuit)
If fuse is not blown, this check is not required.
1. Turn starting switch to OFF position.
2. Disconnect connectors CM01, R18, and starting motor terminal B, and connect
T-adapter to female side of R18.
Between R18 (female) (3) and ground Resistance Min. 1 M
z