DTC 14

Fig. 021 - WIRING DIAGRAM for Code 14 Coolant Sensor Circuit (Signal Voltage Low). VIN 8, VIN W:

CODE 14, COOLANT SENSOR (SIGNAL VOLTAGE LOW)

The Coolant Temperature Sensor uses a thermistor to control the signal voltage to the ECM. The ECM applies a voltage (5-6 volts) on CKT 410 to the sensor. When the engine is cold the sensor (thermistor) resistance is high, therefore the ECM will see a high signal voltage.
As the engine warms, the sensor resistance becomes less, and the voltage drops. At normal engine operating temperature the voltage will measure about 1.5 to 2.0 volts at the ECM terminal C10.
Coolant temperature is one of the inputs used to control:
a. Fuel delivery.
b. Spark Timing (EST)
c. Knock Control (ESC)
d. Idle (IAC)
e. Convertor Clutch (TCC)
f. Canister Purge (CCP)
g. Air Management (A.I.R.)
h. EGR
i. Cooling Fan

Fig. 020 Chart - Code 14 Coolant Sensor Circuit (Signal Voltage Low):

Code 14 will set if signal voltage indicates a coolant temperature above 275°F (134°C) for 4 seconds.
1. Check to see if code was set as a result of hard failure or intermittent condition.
2. This test will simulate a Code 15. If the ECM recognizes the open circuit (high voltage) and sets Code 15, then the ECM and wiring is OK.
3. If a Code 14 repeats, then CKT 410 is shorted to ground or the ECM is faulty.