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The radiator cooling fan is not working properly. I have bypassed its own system installed a aftermarket relay to have the fan working at all times. But now the check engine light is on with a code that translates to cooling fans system not working properly. Where can I find an accurate schematic or plan of diagnosis to have this fixed the right way?
Hi, You probably have a faulty engine coolant temperature sensor or if the sensor tests OK, a wiring problem between the sensor and the ECM. Hopefully the problem is not in the ECM. If the sensor is faulty, replace it and restore the fan wiring to the way it was and see how it goes This sensor is connected to the ECM, which controls the radiator fans. Here is a link that may be of some help. http://www.autozone.com/repairguides/GM-…
I have a 2010 m2 that someone before me added a fan switch to and it sometimes will cause the check engine light to come on. Sometimes it goes off with the switch and other times it takes the ecm kicking on the fan to make it go off. Turning the switch on doesn’t always cause the light to come on immediately so it is kind of hit and miss. The only thing I can think of that may cause my problem is the ecm may be monitoring something like temp, fan state on/off or something similar at various times and registers a reading that it f finds out of tolerance based off of it’s own output commands and throws the light on until it thinks it has been corrected.
