Pto/blower/cruise problems

Maybe the brake switch?

 

Are you refering to the switch that triggers the brake lights or the air switch for the parking brake. If the truck is running a high idol in park and i push in the tractor brake button it will cut off the idol, you think that could have a short?

 

It could be either one, so check them both.

 

Well which ever one it is i think its finally completly crapping out. Today i couldnt get it to stay on eather. If that dosent fix it ill fix it with a matchbook and some gasoline lol

 

I think your truck is overdue for some shop time.

 

I have a shop and its been in lol i keep up with the maintenience like clock work but i havent spent much time chasing this problem. Seems to only act up when the blower is under load. I can park the truck in the shop and set it at a high idol and itll stay there the entire day. My coustomers wouldnt be to happy if i messed with it while trying to pump off lol

 

Hi, years later and i came across this . I am having the same problem on my truck. Can you please help ? How did you finally solve the problem? What was the fault?

 

I’m having the same exact problem. While running the PTO for the blower the cruise constantly cuts out. Sometimes I can reset it sometimes I just have to wedge the pedal with a screwdriver.

The issue is the speed sensor that’s on the tail of the transmission. Although the gauge works fine it’s showing a speed in the engine ecm.

This is a 94 Peterbilt with a Cat engine. I bypassed the clutch pedal switch with a wire and that wasn’t the issue nor is it the brake switch.

While actively using the PTO and blower I hooked up the engine to CAT ET software and monitored every sensor.

The vehicle speed signal kept jumping up to as high as 18 mph which in turn kicks out the cruise set rpm because the idle cruise speed limit is set to 2mph. I changed it to the highest which is 15mph and started using the PTO again and once the ecm saw an idle speed of 15+ it kicks off the cruise again!!!

Long story short I unplugged the speed sensor for now and the cruise high idle has been working fine and hasn’t cut off the PTO blower.

I’m going to replace with a new speed sensor and see if it’s still detecting a speed while parked. If it doesn’t detect a speed than the sensor is working like it should. If it still detects a speed while parked there is a chafe in the wiring somewhere that’s altering the signal to the ecm