DD15 fan clutch not coming on when engine gets hot

I have a 2012 cascadia with dd15 engine..just started overheating on last trip..The fan is not coming on when reaching the hot temperature. I've been troubleshooting problem, I can get the clutch to engage by taking off the lead from the fan clutch solenoid. This tells me the clutch is ok. Solenoid is a normally closed circuit.....this also seems that the solenoid is ok also.....what else tells this solenoid to allow the fan to come on?

 

In pretty sure a signal from the computer tells the fan to come on when engine get hot. Also controlled via a/c circuit. Check the filter on the air solenoid isn't blocked up with oil also. That will stop the fan coming on. Had this numerous times on my kenworths.

 

Most of the time there will be a separate temp sending unit for the gauge, one for the fan then a sensor for the ecm.

 

I hook up my fan with manual switch. The computer sometime's not smart enough.

 

I have a 2016 Freightliner with a DD 15. I have replaced the fan solenoid,but fan will not kick on till temp gets to the red. help

 

Did you ever figure out the issue. I hVe the same thing going on.

 

What was your solution?

 

I know this is an old thread but I’m having the same problem with my 2013 freightliner. My truck use to never get to 200 degress but now I have to use my manual fan switch to keep the temperature down. My fan also kicks on with the ac too. But with regular operations the fan won’t turn on.

 

You found out what it is?