Chrysler never did anything with Hyundai. I just used them as an example. Sorry that I didn't clarify that. The only thing they have in common is Hyundai, Toyota, and Chrysler are the top three manufacturers in the world when it comes to customer-friendly business practices, at least according to one high-level national trainer.
All electronic fuel injection systems work nearly the same way. If you want to look for the coolant temperature sensor it has to have two wires because the ground return wire is where the computer monitors that it is connected properly. Most cars that have a temperature gauge on the dash use a different sensor for that and it only needs and has one wire.
To add to the confusion, there are three different possible sensors for your car. If you find a single-wire sensor you have to keep looking for a two-wire sensor. You could also have a three-wire sensor that incorporates both of them together.
When we're looking at the cause of a dead cooling fan there are actually three circuits to consider. The first one is the sensing circuit. The second is where the computer turns on the relay, and the third is the high current to the fan motor that is switched on and off by that relay. On most cars the computer will turn the fan on when the sensor is disconnected. That is because there is no way to know how hot the engine is or if it's overheating, so they run the fan just in case to be safe. The quick test is to unplug the sensor. If the fan turns on you know the high current circuit is working, the motor is good, the relay is okay, and the computer has control over it. That also tells you the wiring for the sensor is okay when the fan turns off shortly after the sensor is reconnected.
I can't find any reference to the fan relay so I don't know if it's an electronic module for variable speed control or if it's a standard relay. There are a number of fan motors available too. Some have four wires indicating they are two-speed motors and will not use a speed control module. If you have a fan relay under the hood, or a low-speed and a high-speed relay, feel if they click when you unplug the sensor. If they do but the fan doesn't run it is usually because the motor is tight and it drew excessive current and blew a fuse.
Saturday, April 27th, 2013 AT 2:16 AM