PB SHOP FOREMAN
Join Date: Aug 2009
Thanked 13 Times in 11 Posts
just go in and put the ecm in test mode....connect it and see if the fan shuts off...it sounds like an ecm problem. pin 11 is the driver for the fan. this is how we check it. we have ran into this a couple of times. need to go into the parameters and check fan run time and change if needed. there is fuse in the fuse box that is marked aux fan and if the fuse is blown this will also keep the fan on. jump the high pressure switch with a paperclip on the harness side and see if the fan status will read off......
SHOP FOREMAN FOR PETERBILT IN THE GREAT STATE OF TENNESSEE.....28YRS JOURNEYMAN TECH