CAT c-15 acert engine fan problems

I have an 05 pete with the Cat C-15 acert. The engine fan will not engage once the air pressure is built up. It will be on when first starting n then will kick off once air builds up.

you can unplug the solenoid and it will kick in. but as far as the switch in the cab wont do anything but turn the light on the dash on. ive replaced the sensors switch and solenoid on the firewall.

any help would be appreciated.

Sounds like a bad switch. Run it by someone with cat ET and have them toggle the input and look for switch command in the software

Monkey Fist Rage