Failure Code [Ca144] Coolant Temperature Sensor High Error - Komatsu PC88MR-10 Shop Manual

Failure code [CA144] Coolant Temperature Sensor High Error

A-Z0-A)
Action level Failure code
L01 CA144
Detail of
High voltage occurs in engine coolant temperature sensor signal circuit.
failure
Action of
Sets coolant temperature to fixed value (90°C) and runs engine.
controller
Engine startability is poor at low temperatures.
Problem on
Overheat prevention function does not work.
machine
Signal voltage from engine coolant temperature sensor can be checked with monitoring
function. (Code: 04105 (V))
Temperature sensed by engine coolant temperature sensor can be checked with
monitoring function. (Code: 04107 (°C))
Method of reproducing failure code: Turn starting switch to ON position.
This failure code appears if sensor connector is disconnected.
Related
Since female connector alone is provided for "socket" used for troubleshooting of this
information
sensor, it is not connectable to female connector on sensor wiring harness side and thus
not usable for check of open circuit (not designed as T-adapter).
Drain approximately 10l l of coolant beforehand, because you may get scalded by
hot water spurting out from mounting location of coolant temperature sensor when
removing radiator cap during checking and replacing coolant temperature sensor.
No. Cause
Defective wiring harness
1
connector
Defective coolant
2
temperature sensor
Open or short circuit in
3
wiring harness
Defective engine controller
4
PC88MR-10
Coolant Temperature Sensor High Error
Failure
(Engine controller system)
Procedure, measuring location, criteria and remarks
1. See descriptions of wiring harness and connectors in "c: Electrical
equipment" in "Checks before troubleshooting" of "Related
information on troubleshooting", and check it.
2. Turn starting switch to ON position.
If this failure code is not displayed, wiring harness connector is defective.
a If this failure code is displayed, perform following checks.
1. Turn starting switch to OFF position.
2. Disconnect connector TWTR, and connect to socket to male side.
a Regard coolant temperature sensor as normal if its resistance is 700
z to 37 kz when coolant temperature is min. 0°C.
Between TWTR (male) (A) and (B)
Resis-
a Coolant temperature-
tance
Resistance characteristics
1. Turn starting switch to OFF position.
2. Disconnect connector J1 and connect T-adapter to female side.
Between J1 (female) (14) and (13) (Coolant
temperature: Min. 0°C)
Resis-
a Use Coolant temperature-Resistance
tance
characteristics table for check on cause 2
as resistance criteria.
If no failure is found by above checks, engine controller is defective.
(Since this is an internal defect, troubleshooting cannot be performed.)
40 Troubleshooting
Troubleshooting by failure code (Display of code)
25°C
50°C
80°C
95°C
(PC88MR-CA144-400-
0°C 30 to 37 kz
9.3 to 10.7 kz
3.2 to 3.8 kz
1.0 to 1.3 kz
700 to 800 z
700 z to 37
kz
40-137