7
−
6
62-11389
Alarm
NO.
Steps
Alarm/Cause
Corrective Action
12
HIGH COOLANT TEMPERATURE - Continued
7.
Check Engine Coolant Temperature Sensor Wiring
a. Inspect harness & control box
connector pins & terminals. (See
wiring schematic Section 10.)
No physical damage to harness.
No damage or corrosion in connectors.
b Check voltage at the sensor con-
nector with the microprocessor
powered up.
Voltage reading should be 2.5
$
0.1 VDC. This veri-
fies microprocessor output and wiring connections to
sensor.
8.
Check Engine Cooling System
a. Compare actual engine tempera-
ture to the microprocessor reading.
Temperature must be within
±
20
°
F (
±
11.1
°
C.)
b. Test operation of engine coolant
thermostat.
Must operate correctly.
c. Check water pump operation.
No seepage at weep hole. Bearings tight and quiet.
Impeller firmly attached to shaft.
d. Check cooling system for scale,
sludge, rust, etc.
Coolant must be clean & clear. No foreign particles or
substances in it. Flush & clean the coolant system as
necessary.
e. Check water pump bypass hose to
thermostat housing for internal
blockage.
Must be clear and open.
