With PFI

Code 14 Chart:

Code 14 Wiring Diagram:

CIRCUIT DESCRIPTION:

The Coolant Temperature Sensor uses a thermistor to control the signal voltage to the Electronic Control Module (ECM). The ECM applies a voltage on CKT 410 to the sensor. When the engine is cold the sensor (thermistor) resistance is high, therefore the ECM will see 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 "YE16".
Coolant temperature is one of the inputs used to control:

^ Fuel Delivery
^ Electronic Spark Timing (EST)
^ Cooling Fan
^ Torque Converter Clutch (TCC)
^ Idle Air Control

NOTE: Because of all the possible color code combinations used on electrical wiring diagrams, always refer to ECM CONNECTOR IDENTIFICATION under ELECTRICAL AND ELECTRONIC WIRING DIAGRAMS

TEST DESCRIPTION: Numbers below refer to circled numbers on the diagnostic chart.

1. Checks to see if code was set as a result of hard failure or intermittant condition.
Code 14 will set if:

^ Engine has been running for more than 10 seconds.
^ Signal voltage indicates a coolant temperature above 135~C (275~F) for 3 seconds.

2. This test simulates conditions for code 15. If the ECM recognizes the open circuit (high voltage) and displays a low temperature, the ECM and wiring are OK.


DIAGNOSTIC AIDS:

^ A "Scan Tool" reads engine temperature in degrees centigrade.

^ After the engine is started, the temperature should rise steadily to about 90 degrees, then stabilize, when the thermostat opens.

^ If the engine has been allowed to cool to an ambient temperature (overnight), coolant and MAT temperature may be checked with a "Scan Tool" and should read close to each other.

^ When a code 14 is set, the ECM will turn "ON" the engine cooling fan.

^ A code 14 will result if CKT 410 is shorted to ground.

^ If code 14 is intermittant, Refer to TESTING PROCEDURES/DIAGNOSIS BY SYMPTOM/INTERMITTENTS.