
RENR9348-01 113
Troubleshooting Section
Expected Result:
The status changes from “OK” to “LOW” when the
sensor is disconnected.
Results:
•
OK – The status
is “LOW” when the sensor is
disconnected. There may be a problem with the
coolant level sensor. Proceed to Test Step 5.
•
Not OK – The status is “OK” when the sensor
is disconnected. The problem is between the
ECM and the ha
rness connector. There may be a
problem with the ECM. Proceed to Test Step 6.
Test Step 5. S
hort the Signal Wire to
Ground and Mo
nitor the Status for
“Coolant Level”
A. Remove elect
rical power from the ECM.
B. Fabricate a jumper wire that is long enough to
create a sho
rt circuit between two terminals at the
coolant level sensor’s harness connector. Crimp
connector pins to each end of the jumper wire.
C. Install the jumper wire between terminals B
(sensor return) and C (sensor signal) on the
harness si
de of the connector for the coolant level
sensor.
D. Restore el
ectrical power to the ECM.
E. Monitor the status of “Coolant Level” on Cat ET
while the j
umper wire is installed.
Note: Wait at least 30 seconds for activation of the
status ind
icator.
F. Remove electrical power from the ECM.
G. Remove the jumper wire. Connect the harness
connector for the coolant level sensor.
Expected Result:
The status
changes from “LOW” to “OK” when the
jumper wire is installed.
Results:
•
OK – The status changes from “LOW” to “OK”
when the j
umper wire is installed. The ECM and the
wiring harness to the coolant level sensor are OK.
Repair: P
erform the following procedure:
Pressurized System: Hot coolant can cause seri-
ous burns. To open the cooling system filler cap,
stop the engine and wait until the cooling system
components are cool. Loosen the cooling system
pressure cap slowly in order to relieve the pres-
sure.
1. Drain the coolant below the level of the coolant
level sensor.
2. Restore electrical power to the ECM.
3. Monitor the status of “Coolant Level” on Cat ET.
Note: Wait at least 30 seconds for activation of the
status indicator.
4. Remove electrical power from the ECM.
If the status of the “Coolant Level” is “OK”, replace
the sensor.
If the status for the coolant level is “LOW”, the
circuit for the coolant level sensor is OK. There
may be an intermittent problem in the harness or
in a connector. Fill the cooling system according to
the procedure in the Operation and Maintenance
Manual. Return the engine to service. If an
intermittent electrical problem is suspected, refer to
Troubleshooting, “Electrical Connectors - Inspect”
for troubleshooting information.
STOP.
•
Not OK – Shorting the harness does not affect
the status on Cat ET. The problem is between the
ECM and the harness connector. There may be a
problem with the ECM. Proceed to Test Step 6.
Test Step 6. Check the Wiring Harness
foranOpenCircuit
A. Remove electrical power from the ECM.
B. Disconnect the J2/P2 ECM connector and the
connector for the coolant level sensor.
C. Fabricate a jumper wire that is long enough to
provide a test circuit between the ECM connector
and the sensor connector. Crimp a connector pin
to one end of the jumper wire.
D. Install the jumper wire’s connector pin into terminal
C on the harness side of the connector for the
coolant level sensor.
E. Measure the resistance between terminal P2-39
and the loose end of the jumper wire.