Powertrain Controls - ECM/PCM

DTC 14 Engine Coolant Temperature (ECT) Sensor Circuit Low (High Temperature Indicated):

CIRCUIT DESCRIPTION
The Engine Coolant Temperature (ECT) sensor is a thermistor that controls signal voltage to the Powertrain Control Module (PCM). When the engine is cold, the sensor resistance is high, therefore the PCM will see high signal voltage. As the engine warms, sensor resistance becomes less and voltage drops.

DIAGNOSTIC TROUBLE CODE (DTC) 14 WILL SET WHEN
Engine coolant temperature greater than 151°C (304°F) for 2 seconds.

ACTION TAKEN (PCM will default to)
The PCM will use 77°C (17l°F) as measured engine coolant temp.

DTC 14 WILL CLEAR WHEN
The fault condition(s) no longer exist.

DTC CHART TEST DESCRIPTION
Number(s) below refer to circled number(s) on the diagnostic chart.
1. This step determines if DTC 14 is a hard failure or an intermittent condition.
2. This test will determine if CKT is shorted to ground.

DIAGNOSTIC AIDS
Check harness routing for a potential short to ground.
After engine is started, the coolant temperature should rise steadily to about 85°C (185°F).
The PCM default value will flash on the data screen intermittently.
Refer to Intermittents. - Intermittent Malfunctions
The "Temperature to Resistance Value" scale may be used to test the intake air temperature sensor at various temperature levels to evaluate the possibility of a "skewed" (mis-scaled) sensor. A "skewed" sensor could result in poor driveability complaints.