DTC 1-2-3 Engine Coolant Temperature Sensor Signal

1-2-3 ENGINE COOLANT TEMPERATURE SENSOR SIGNAL

Condition(s) for DTC
^ The MFI module is dependent on the Engine Coolant Temperature (ECT) signal for computing the injection period, for example when starting from cold. If the module receives a signal equivalent to a temperature lower than -87°C (-125°F) (high signal) or higher than 175°C (350°F) (low signal), it will interpret the signal as a fault and the DTC will be recorded.

Substitute value
^ The MFI module assumes a substitute value equivalent to a temperature of 80°C (175°F).
^ The ICM starts the engine cooling fan at half speed.
^ The MFI module transmit's a temperature signal equivalent to a value of 150°C (300°F) to the ICM.

Fault source(s)
^ Signal too high:
- Signal lead short-circuited to supply.
- Open-circuit in signal lead or ground lead.
- ECT sensor faulty.
- Contact resistance in connections.
^ Signal too low:
- Signal lead short-circuited to ground.
- ECT sensor faulty.

Fault symptom(s)
^ Engine is difficult to start or refuses to start in certain temperature ranges.
^ Driving problems during warm-up phase.
^ Post-running of engine cooling fan.