Originally Posted by pizzaguy

Yea, the coolant light can mean several things. Sounds like the ECM lite the coolant light because it can't talk to the Fan Module.
I know for a fact that if the ECU can't get a response from the fan module (the ECU "tickles" the Fan Module several times a second), it lights the coolant light.

On the OTHER hand, if the Fan Module does not feel the tickle, it puts the fan motor into emergency mode. That is, the module turns the fan on 100% full, since it is then not gettting instructions from the ECM as to how warm the coolant is getting.

To summarize: There is a single wire running from the fan module to the ECM. This is a bi-directional bus, pulses from one module are felt by the other module and if this communication breaks down, and IF both modules are healthy, then the ECM lights the Coolant light and the Fan Module turns the fan on fullly.

Yup, sounds like you have a bad fan module.