HELP.. 05 Pete 335 erratic clutch fan

Please help.. I have an 05 Peterbilt 335 w/ and 8.3l cummins ISC CM850. One day I was loading my pete 5 pack car hauler and I heard the engines fan cut on then imminently cut off... 2 second later it comes on. then off... on and off again constantly. running for no more then a split second then cutting off. you could set a clock by how intermediate it is... eventually stopped 30 mins later and seemed fine for a week. then one day it comes back and has not stopped cutting on and off constantly since. its a true ghost. i started to target areas that would want to send signal to the solenoid. downloaded the cummins engine fan troubleshoot tree. had since replaced the high pressure switch on the ac line, replaced thermostat, cleaned my engine grounds, replaced the clutch fan solenoid, checked and cleaned ecm (looked good) with contact cleaner, cleaned all my relays and solenoids (on the passenger side firewall inside the protected case) in the harness sharing the power to the clutch fan solenoid. erratic is the prefect word for how it runs on and off immediately. I'm running out of options to check on my own. you can override the fan from the toggle switch in the cab but when switch down to auto it goes crazy. any help would be appreciated truly. truck was purchased up north.... so I'm positive there and grounds I'm forgetting. please help

 

would this problem still occur at the ac switch even if the ac is off? cause it acts exactly the same with ac off. thank you i will still check

 

would this problem still occur at the ac switch even if the ac is off? cause it acts exactly the same with ac off. thank you i will still check

 

yes sir. I will report back to you tomm. with my findings.

 

I did find this on the firewall. It’s at the end of the harness that tails off the clutch fan Solonoid power/ground. Not sure what it is but I also cleaned and got all corrosion off.