P015

Circuit Description

The Engine Coolant Temperature (ECT) sensor is a thermistor, a sensor whose resistance varies with temperature. The ECT sensor signal is on CKT 410 and sensor ground on CKT 476. As the temperature increases, sensor resistance decreases. High coolant temperature will result in low signal voltage on CKT 410. Code P015 sets because the coolant temperature cannot be less than -29°C when IAT is greater than -5°C.

Test Condition(s)

1. Codes P037 and P038 not set.
2. IAT sensor value -5°C or greater.

Failure Condition(s)

Coolant sensor value -29°C or less for 2 seconds.

Action Taken

1. PCM turns 'ON' the 'SERVICE ENGINE SOON' MIL.
2. PCM uses the IAT sensor values in place of the engine coolant temperature sensor for the first 4.25 minutes of engine operation, and a value of 90°C afterwards.
3. Transaxle shift adapts are maintained at current levels.

Notes on Fault Tree

1. With the ECT sensor or wiring open circuited, PCM Data PDO4 will read -29°C or less.
2. Checking for an open in CKT 410 from PCM to sensor. If PD04 shows 135-151°C with the coolant temperature sensor wiring harness terminals jumpered together, then CKT 410 and 476 are OK.
3. Checking for an open in the sensor ground CKT 476 from sensor pin A to the ground splice. If shorting pin A to ground causes PD04 to show 135-151°C, then there is an open in CKT 476.
4. Checking the PCM's ability to recognize low voltage on terminal '1B5' ECT Sensor input. If grounding terminal '1B5' causes PD04 to show 135-151°C, then there is an open in CKT 410 from the PCM to the coolant temperature sensor.