DTC 15

Fig. 038 - Chart - Code 15 Open Coolant Sensor Circuit.:

1. Checks system by introducing a large air leak to the engine and see if this will cause the dwell to decrease and to see if problem is still present.
Normal reading is a decrease in dwell. Somewhere around 10°.
2. Checks to see if the fault is the coolant sensor or lack of voltage to the coolant sensor.
Normally you should have 5 volts across the coolant sensor connector terminals.
3. Determines whether the low voltage at the sensor connector is due to opens in the coolant sensor wires or good terminal contact.
Normal voltage should be about 5V from ECM Terminals "17" to "8".
4. Checks resistance of the coolant sensor. If the resistance is within 1000 ohms specifications, coolant sensor is not faulty; therefore, check for corrosion at the connector or low coolant level.