My 2000 Neon Keeps bringing back the P1490 check engine light code (Low speed fan open circuit). What I have done so far;

• Ran a self-test on the instrument cluster. (While holding the trip reset button down turn the key to the "on" position. watch to see if the gauges sweep during this test. If they do not, the cluster is bad and will need to be replaced.) The gages all swept just fine.
• Warmed the engine up by running it, the temperature gage tracked the engine temp thus the temperature sensor is working.
• Checked Fan Fuse (bench test - fuse is conducting)
• Check Fan Relay (bench test - relay is functioning)
• Checked the fan motor (Turned on the AC - fan motor runs)
• Ran conductivity test from the fan connector to the relay – conductivity is fine.

My questions:
What exactly constitutes the “low speed fan circuit” that is being monitored by the computer for this error code?
What other possibilities are there in this circuit that could cause this error code and how do I test them?

 

the code you got is for low speed fan circuit and the relay could be whats causing that too happen or the temperature sensor on it, that's what makes the fan kick in on it,try flushing the engine and radiator out on it and try another low speed fan relay,its possible you got a bad one from the parts store,id also flush the heater core out real good on it,keep one thing in mind after market parts are mostly made over sea,s and aren't always as good as they seem to be,good luck. one part of the relay can be good and the other part bad,so yes in answer to your question it could still be a bad relay on it.

 

Thank you for the response I appreciate it.

I have seen this response in other forums on the web, all with the same result...not effective. That makes sense to me since this error code is an open circuit code and not a fluid level or clarity indication, unless I'm missing something such as a sensor in the low speed fan circuit that would be effected by the fluid clarity. Is there one? I have not heard of anything along those lines except possibly the temperature sensing gage and that would not provide an open circuit indication because of the fluid needing flushed. It might provide an open circuit indication if it were malfunctioning (assuming it is even in the low speed fan circuit), but that would be indicated by the lack of the temperature gage on the dash to track engine temperature. Since I have validated that the temperature gage is indeed tracking the engine temp properly we can therefore assume that the temp sensor is working properly.


To preclude that possibility I set up a functional test bench and performed a complete functional test of the relay on the test bench. All aspects of the relay are functioning properly.

This brings us back to the original questions:

What exactly constitutes the “low speed fan circuit” that is being monitored by the computer for this error code?
What other possibilities are there in this circuit that could cause this error code and how do I test them?

 

Yesterday I went down to the parts counter at the Dodge dealer in Auburn Washington to see if I could buy the parts for the "low speed fan control relay circuit". That is the whole system...they could not help me and sent me to the service department. The service department rep told me ... and I quote "I don't have a clue what a low speed fan control relay circuit is". However, if I would bring the dead car to them they would fix it at whatever rate they felt like charging me. At the moment I'm living off the food bank and gas cash to get to a job interview is hard to come by so I have to do this myself...no other option, this is frustrating.

I'm starting to empathize with that east coast state that a couple years ago tried to get the "right to maintain" bill on the ballet that would require auto makers to make available to auto owners all of the maintainability information required to maintain their own vehicle. I never did hear if they succeeded, but I wish we had that law here.

Be that what it may, can anybody provide a succinct definition of what constitutes the "low speed fan control relay circuit" that is being monitored by the computer for this error code on a 2000 Neon?

 

The error code now goes away on its own and then comes back a few days later. Fortunately it went away long enough to pass emissions.