The CTS provides an engine coolant temperature input to the ECU, which will then enrich the air/fuel mixture delivered by the injectors when the engine coolant is cold. Based on the CTS signal, the ECU will also control engine warmup idle speed, increase ignition advance and inhibit EGR operation when the coolant is cold.
Disconnect the wire harness connector from the CTS and measure the resistance of the sensor with a high input impedance (digital) volt-ohmmeter. The resistance should high when cold and be less than 1000 ohms with the engine warm. No reading at all-defective
Checking the relay you have to remove and test the coil and switch side. The coil side should be about 80ohm and the switch side will read infinite. any reading other then this -replace it.
Beware they are 3 -different types of auto relays-it should have a picture on the relay, showing the coil and switch side.
Monday, September 3rd, 2007 AT 2:33 AM