TM 5-3805-291-23-1
ELECTRICAL SYSTEM TESTS, INSPECTIONS, AND ADJUSTMENTS - CONTINUED
0013 00
ENGINE TEMPERATURE SENSOR OPEN OR SHORT CIRCUIT TEST
0013 00
N OT E
Use this procedure to troubleshoot anysuspect problems with following sensors:
a.
Intake manifold air temperature sensor.
b.
Coolant temperature sensor.
c.
Fuel temperature sensor.
This procedure covers folowing diagnostic codes:
l
a.
110-03 Engine Coolant Temperature Open/Short to +Batt
b.
110-04 Engine Coolant Temperature Short to Ground
c.
172-03 Intake Manifold Air Temp Open/Short to +Batt
d.
172-04 Intake Manifold Air Temp Short to Ground
e.
174-03 Fuel Temperature Open/Short to +Batt
f.
174-04 Fuel Temperature Short to Ground
Troubleshooting procedures for diagnostic codes of each temperature sensor are identical.
Temperature sensors are passive sensors that ha e two terminals. Temperature sensors do not
v
require supply voltage from ECM.
ECM continuously outputs a pull-up voltage on circ it for sensor signal wire. ECM uses this pull-
u
up voltage in order to detect an open signal circuit.
When ECM detects presence of a voltage that isabove a threshold on signal circuit, ECM will
generate an open circuit diagnostic code 03 for sensor.
If sensor is disconnected at sensor connector:
Presence of pull-up voltage at sensor connecor indicates that wires from sensor connec-
t
tor to ECM are not open or Shorted to Ground.
Absence of pull-up voltage at sensor connectorindicates an open signal wire or a Short to
Ground.
Voltage at sensor connector is different fr m pull-up voltage, signal wire is Shorted to
o
another wire in harness.
427-C0674