Engine fan wont turn off

[JimT]

That picture you posted is nice for finding intermittent problems, but if something is constantly reporting an incorrect value then it might not be noticeable there. Even still, 5.17v for the ambient air sensor seems off as they are usually in the 0-5v range. That could be the issue, either a bad sensor or wire on that circuit.

See Rawze's earlier post about ambient air temp bug with 870's.

Pull up Data Monitor and see what values the sensors are reporting. You can also see there what reason the ECM has for operating the engine fan. If the ambient air temp is reporting maximum high temp then the ECM might think it needs to run the fan to prevent over heating?

Also, what fault code was showing for the fan control and was it active or inactive? 1 count or many counts? recent or old? It may have been corrected by something you already replaced.