Just to clarify, when you replaced the PCM was this an issue with the old PCM?
Did you use a new PCM or a used one?
The way this works is the temperature sensor tells the PCM what the engine temperature is and that will determine if the fan needs to be on.
Have you removed the thermostat and put it in boiling water to find out if it is opening? It sounds like if you replaced the thermostat that this is not the issue and that it may be opening but the temperature sensor is either faulty or the PCM that you replaced as an issue.
The quickest way to test this is to put the old PCM in (which will cause the other issue to come back) and see if the fans come on. If they do, then you know the PCM is the issue.
https://www.2carpros.com/articles/how-to-check-an-electrical-relay-and-wiring-control-circuit
However, if the temperature sensor is working and the thermostat is in fact opening in boiling water then we need to check the relays to find out if they are the issue or we have another PCM issue.
We need to check the purple wire from the radiator fan relay to the PCM and see if the PCM is grounding this terminal. If it is then the PCM is commanding it on, it is just not coming on. If the fan works when the A/C is on, then I suspect we have a PCM issue.
Let's start with this info and we can go from there.
Thanks
Images (Click to make bigger)
SPONSORED LINKS
Thursday, May 12th, 2022 AT 7:08 PM