Test ECT - Engine Coolant Temperature Sensor

Fig 1: Identifying ECT Connector Terminals

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 step 2).

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 connector terminal (Blue/White wire on 1.8L; Yellow/Black wire on 2.2L). If continuity is not present, repair circuit between ECA and ECT sensor. If continuity is present, go to step 3).

3) Checking SIGRTN Resistance  With key 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 step 4).

4) Checking ECT Ground Circuit  With key off, check for continuity between SIGRTN and GND test pins. If continuity is not present, repair circuit as necessary. If continuity is present, disconnect ECT sensor. Measure sensor resistance.

5) ECT Sensor Resistance  Compare resistance to specifications shown in RESISTANCE SPECIFICATIONS (ECT SENSOR)  . If resistance is 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.