I have a 2001 Freightliner FLD120 with a Series 60 Detroit. I have been having a problem with the cruise control. A lot of the time I will have to tap the brake pedal to get it to work. Sometimes it will stop working for an entire day of driving. Sometimes I may have to tap the brake pedal 20 times or the clutch pedal then the brake pedal in order to get it to work. The next time I use the brake to stop I will have to tap it 3 or 4 times to get the cruise working again. I know that this could be service brake switch but I am not sure which one that is in the manifold. Recently I have had the engine die going down the road. I know this sounds every strange but it will not start again until I tap the brake pedal 3 or 4 times.... Crazy stuff. Please help
Optional Information: Make: Freighliner Model: FLD120 Year: 1991 Engine: Series 60 Detroit
Hi I will help with your problem Please do not rate until all your questions are answered that way you wont have to pay twice Use reply to expert link.First let's start with cruise control if I ask to many questions about both things it gets confusing.I need to know if your brake lights are staying on intermittently?Do you have Jake brakes or any other kind of engine brake?If you have Jake brakes do you know if they were factory installed,or dealer installed,don't know,or customer installed?
Yes, it has factory installed Jake Brakes, or at least I am prettry sure they are factory. I have not noticed the brake lights staying on intermittently.
Ok if it was the brake switch then your brake lights would also be on whenever it acts up. So I think it is your clutch switch,when you hit brakes it could be making the clutch switch return all the way to off position.That is the only thing that would have these symptoms, without other symptoms.So first check the adjustment on your clutch arm under dash[that is why I needed to know about Jake brakes]and make sure it is clicking on and off as you first push down on clutch pedal you should here it clicking leave engine and key off then put your ear down there so stand outside truck or on step push clutch pedal down with your hand about 2" you should hear it if not try adjusting if not replace. Also check and make sure wires are on good if you have any questions even after you rate my answer come back to this link and ask I will get back to you have a great day spanky41091.7972291319
The wires are on tight and the switch clicks properly every time.I have checked this in the past but just checked it again. I was a diesel mechanic for 12 years. Just dont have any experience with this issue and everything that I know to check so far has not worked. 99% pf the time tapping the brake pedal causes it to start working. When I have to stop it will quit working. Sometimes it will just quit working while the cruise is on and I will have to tap the brake to get it to come back on. I have not seen my brake lights on though.
Some modals have a separate switch for brake lights or a switch that is two parts or 4 wires and internally has two switches in it[I don't know if that is your case]Look on the treadle valve under truck Sometimes they install a brake switch for cruise only in that valve. You can figure out which one it is by disconnecting one wire off the switch and test cruise they are normally open switches so just leave open and test cruise or pto with cruise switches.Another thing to check is under brake pedal the rubber boot gets full off dirt and does not return all the way.Pull pin for brake pedal they also can hang up remove rubber boot blow out dirt use penetrating oil or never seize to lube pin ,pedal and button under boot.41092.5382132755
Experience: I worked on all types of equipment semis,forklifts,farm,ect.
I have looked at all of these things with no luck. Replaced the clutch switch, Replaced the service brake switch, replaced the park brake switch. It was still intermittent for a week or so. The cruise has officially quit working now. The PTO/High Idle will work but when I release the park brake it stays idle up instead of returning to idle. Also the dying problem turned out to be a loose wire on the radiator level sensor. Still pulling my hair out.
I'm sorry about not getting back to you right away my computer crashed and I spent two days putting in new hard drive and all my gunk.Pto works off of rpm, cruise works off of speed sensor,and you also have another brake switch,it's not for brake lights its for park brake.You can follow air lines to manifold behind dash and park brake switch, that is the sensor that is bad.
I have replaced the park brake switch as i stated in previous reply
I understand you replaced both brake switches,park and service.{i just reread our conversation}There may also be one for cruise,but before guessing any more do you have a ohm meter and a test light so we can diagnose?Do you have any check engine light coming on?If you have these we can diagnose, if not consider buying one that will save you money not only now but in the future.You don't need A high tech one, just a basic digital volt ohm meter?Preferably auto ranging.
Yes i have one
Good on the back side of trans by the u-joint is a electrical sensor with ether two or 4 wires on it,it turns into trans and reads off of a slotted ring to determine speed and sends that info to engine ecm and then to speed-o and brake switch,and cruise relay. Disconnect it, and ohm out the sensor and give me your readings.I would give them to you but they are different depending on 2-4 wireThat is the speed sensor for cruise and speed-o.
4 wire 1st pair 0.98 ohms 2nd pair 0.99 ohms
Then that is bad, on both sides,replace sensor.One reading should be about 800ohms and the other should read about 1250-1400ohms,so the sensor is bad.R&r sensor turn all the way in and then back off 1/2-3/4 turn.Good luck spanky Oh it is called a 4 wire speed sensor,then lock down nut do not let sensor turn and don 't tighten to much you will brake the sensor use a small amount of lock tight if you are worried about it coming loose41115.4755836806