Circuit Test ECT - Engine Coolant Temperature Sensor

Fig 1: ECT Connector Terminal ID

NOTE: Enter this test only when a Code 09 is displayed during self-test procedures (KOEO or KOER), or when directed here from another CIRCUIT TEST. To prevent unnecessary diagnosis, inspect coolant level, oil level, cooling fan, thermostat and airflow to radiator for obstruction before electronic testing.

CIRCUIT PIN IDENTIFICATION

Circuit	Breakout Box Pin No.	ECA Pin	Wire Color
1.8L
ECT	7	2Q	Blue/White
SIGRTN	46 & 49	2D	Black/White
2.2L Non-Turbo
M/T
ECT	7	2Q	Yellow/Black
SIGRTN	46 & 49	2D	Green/Yellow
A/T
ECT	7	2E	Yellow/Black
SIGRTN	46 & 49	3D	Green/Yellow
2.2L Turbo
ECT	7	2E	Yellow/Black
SIGRTN	46 & 49	3D	Green/Yellow

1) Checking System Integrity Visually check all wiring, connectors and components for evidence of damage, shorting or looseness. If a fault is found, repair as necessary. If no fault is found, go to next step.

2) Checking ECT Circuit Ensure engine is at operating temperature. Turn ignition off. Install breakout box, leaving ECA disconnected. Disconnect ECT sensor connector. Turn ignition on. Measure voltage between ECT test pin and ECT terminal at ECT sensor connector. If continuity is not present, repair circuit between ECA and ECT sensor. If continuity is present, go to next step.

3) Checking SIGRTN Resistance With ignition off, disconnect ECT sensor. Check for continuity between SIGRTN terminal of ECT connector and SIGRTN test pin. If continuity is not present, repair circuit. If continuity is present, go to next step.

4) ECT Sensor Resistance Compare resistance to specifications shown in RESISTANCE SPECIFICATIONS (ECT SENSOR) . If resistance is not as specified, replace ECT sensor. If resistance is within specification, measure resistance between ECT and SIGRTN test pins. If resistance is 500-1000 ohms, replace ECA. If resistance is not 500-1000 ohms, replace ECT sensor.

RESISTANCE SPECIFICATIONS (ECT)

Temperature °F (°C)	Ohms
68 (20)	2200-2700
104 (40)	1000-1300
140 (60)	500-650
176 (80)	290-350