ELECTRICAL SYSTEM TESTS, INSPECTIONS, AND ADJUSTMENTS - CONTINUED
ENGINE TEMPERATURE SENSOR OPEN OR SHORT CIRCUIT TEST
N OT E
Use this procedure to troubleshoot anysuspect problems with following sensors:
Intake manifold air temperature sensor.
Coolant temperature sensor.
Fuel temperature sensor.
This procedure covers folowing 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 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
require supply voltage from ECM.
ECM continuously outputs a pull-up voltage on circ it for sensor signal wire. ECM uses this pull-
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-
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
Voltage at sensor connector is different fr m pull-up voltage, signal wire is Shorted to
another wire in harness.