E015

Code E15:

Sensor Circuit:

DESCRIPTION:

The coolant sensor is a thermistor, a sensor whose resistance varies with temperature. The coolant sensor signal is on CKT 410 and sensor ground on CKT 476. As the temperature of the sensor increases, sensor resistance decreases. A high coolant temperature will result in low signal voltage on CKT 410. Code E15 sets because the coolant temperature cannot be less than -38°C when the MAT is less than -5°C.

TEST CONDITIONS:

1. Codes E37 and E38 are not set.
2. MAT Sensor value -5°C or greater.

FAILURE CONDITIONS:

Coolant Sensor Value -38°C or greater.

ACTION TAKEN:

1. PCM/ECM turns on "SERVICE ENGINE SOON" telltale.
2. PCM/ECM uses the MAT sensor values in place of the coolant temperature sensor for the first four minutes of engine operation, then the value of 90°C is used.

NOTES ON FAULT TREE:

1. If sensor is open, parameter P.0.4 should read -38°C or less. If not, the sensor signal is not open, see NOTE ON INTERMITTENTS.

2. Checking for open sensor signal CKT 410 from the PCM/ECM to sensor connector. If parameter P.0.4 reads 148°C to 151°C with connector shorted then CKT 410 and 476 are OK.

3. Checking for an open in sensor ground CKT 476 from sensor pin "A" to the ground splice. If shorting pin "A" to ground causes P.0.4 to read 148°C to 151°C then there is an open in CKT 476.

4. Checking for the PCM/ECM's ability to recognize a short to ground or low voltage on terminal E16, coolant sensor input. If grounding E16 causes P.0.4 to show 148°C to 151°C, then there is an open in CKT 41 from the PCM/ECM to the coolant sensor.

5. Checking for faulty mating of the PCM/ECM connectors. Fault is most likely at the PCM/ECM connector or the PCM/ECM. Before replacing the PCM/ECM, perform "PCM/ECM Replacement Check", CHART C-1.

NOTE ON INTERMITTENTS:

Manipulate CKT 41O and 476 wiring, the coolant sensor and PCM/ECM connector, while observing PCM/ECM parameter P.0.4. If the failure is induced, the coolant temperature will jump from its normal value to the open circuit reading of -38°C or less. Disconnect and reconnect both the coolant sensor and PCM/ECM connections and ensure that they are latched before replacing components. If wiring and connectors check out OK, substitute a known good coolant sensor and retest.