
142 RENR9348-01
Troubleshooting Section
•
Not OK – The reading is not within the
specification.
There is an electrical problem with
the engine speed/timing sensor.
Repair: Perfo
rm the following procedure in order
to check and install the new sensor assembly:
1. Before you ins
tall the new sensor assembly,
measure the resistance of the new sensors.
If the resista
nce measurements of the new
sensors are within the specifications, install the
new sensor assembly in the engine according
to the follow
ing procedure:
a. Loosen the bolt and remove the bolt that
holds the sen
sor to the engine.
b. Ensure that an O-ring is installed on the new
sensor assem
bly. Verify that the O-ring is
free of damage.
c. Prior to ins
tallation, lubricate the O-ring with
clean engine oil.
d. Seat the sen
sor and tighten the bolt.
If the sensor will not seat, replace the sensor.
e. Ensure that the harness is secured in the
proper location.
2. Verify that the repair eliminates the problem.
STOP.
i02410343
Engine Temp
erature S en sor
Open or Short Circuit - Test
SMCS Code:
1439-038-TA; 1906-038
System Operation Description:
Use this procedure to troubleshoot any suspect
problems with the following sensors:
•
Intake manifold air temperature sensor
•
Engine coo
lant temperature sensor
•
Fuel temperature sensor
•
Engine oil temperature sensor
This proce
dure covers the following diagnostic codes:
•
110-03 Engine Coolant Temperature open/short
to +batt
•
110-04 Engine Coolant Temperature short to
ground
•
172-03 Intake Manifold Air Temp open/short to
+batt
•
172-04 Intake Manifold Air Temp short to ground
•
174-03 Fuel Temperature open/short to +batt
•
174-04 Fuel Te
mperature short to ground
•
175-03 Engine Oil Temperature open/short to +batt
•
175-04 Engine Oil Temperature short to ground
The troublesh
ooting procedures for the diagnostic
codes of each temperature sensor are identical.
The temperature sensors are passive sensors that
have two termi
nals. The temperature sensors do not
require supply voltage from the Electronic Control
Module (ECM).
Pull-up Voltage
The ECM conti
nuously outputs a pull-up voltage
on the circuit for the sensor signal wire. The ECM
uses this pull-up voltage in order to detect a problem
in the signa
l circuit. When the ECM detects the
presence of a voltage that is above a threshold on the
signal circuit, the ECM will generate an open circuit
diagnostic
code (03) for the sensor.
If the sensor is disconnected at the sensor connector,
the presenc
e of pull-up voltage at the sensor
connector indicates that the wires from the sensor
connector to the ECM are OK. If the sensor is
disconnec
ted at the sensor connector, the absence
of pull-up voltage at the sensor connector indicates
a problem in the signal wire. If the sensor is
disconne
cted at the sensor connector and the voltage
at the sensor connector is different from pull-up
voltage, the signal wire is shorted to another wire in
the harne
ss.