P014

DTC PO14:

Sensor Circuit:

DESCRIPTION
The Engine Coolant Temperature (ECT) sensor, which is located behind the distributor on the thermostat housing, is a thermistor, a sensor whose resistance varies with temperature. The ECT sensor signal is on CKT 410 and sensor ground on CKT 808. As the temperature of the sensor increases, resistance decreases. A high coolant temperature will result in low signal voltage on CKT 410. Code P014 sets because the coolant temperature cannot be greater than 147°C (296°F) when the Intake Air Temperature (IAT) is less than 100°C (212°F).

TEST CONDITIONS
1. Codes P037 and P038 not set.
2. IAT of 100°C or less.

FAILURE CONDITIONS
Coolant sensor signal 147°C or greater for 2 seconds.

ACTION TAKEN
1. Powertrain Control Module (PCM) turns "ON" the "Service Engine Soon" Malfunction Indicator Lamp (MIL).
2. PCM uses the IAT sensor values in place of the engine coolant temperature sensor for the first ten minutes of engine operation, then the value of 90°C is used.

NOTES ON FAULT TREE
1. With the coolant sensor or wiring shorted, PCM Data PD04 will read 147°C or greater. If not, then the sensor or wiring is not shorted; refer to "NOTES ON INTERMITTENTS."

2. Checking for sensor shorted or CKT 410 shorted. If the parameter value stays at 142°C or greater with the sensor unplugged, the short is in CKT 410 between sensor pin "B" and PCM terminal "3E16."

3. Checking for faulty mating of PCM connector. Fault is most likely at the PCM connector.

NOTES ON INTERMITTENTS
Manipulate CKT 410 wiring, ECT sensor connector, and PCM connector while observing PCM Data PD04. If the engine coolant temperature jumps from a normal reading to 147°C or greater, repair the intermittent short to ground on CKT 410. Remove and reconnect both the ECT sensor and PCM connectors and retest before replacing any components. If wiring and connectors check out OK, substitute a known good ECT sensor and retest.