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Cat Man
Cat Man, Cat Engine Expert
Category: Medium and Heavy Trucks
Satisfied Customers: 8420
Experience:  I am ASE Master Truck Certified.
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Cruise not working, 2001 379 peterbilt cat 6nz, traced wires

Customer Question

cruise not working
JA: What's the make/model/year of your truck? Engine type?
Customer: 2001 379 peterbilt cat 6nz
JA: Are you fixing your truck yourself? What have you tried so far?
Customer: traced wires and switches checked ecm found ecm has service brake ON new switch also found wire 281 has power not sure why
JA: Anything else you want the truck mechanic to know before I connect you?
Customer: truck had detroit 60 series the last owner installed cat
JA: Sometimes things that you think will be really complicated end up being easy to fix. The heavy truck mechanic I'm going to connect you with knows all the tricks and shortcuts.
Customer: get'er done
Submitted: 1 month ago.
Category: Medium and Heavy Trucks
Customer: replied 1 month ago.
cruise switches work on ET no high idle jakes work ecm parameters all look good cab grounds ok battery clean and good had data link problem customer came back after it was fixed and said cruise is not working. has some creative wiring under dash but nothing obvious. do all peterbilts use park brake switches could not find one
Customer: replied 1 month ago.
hello??????
Customer: replied 1 month ago.
Posted by JustAnswer at customer's request) Hello. I would like to request the following Expert Service(s) from you: Live Phone Call. Let me know if you need more information, or send me the service offer(s) so we can proceed.
Customer: replied 1 month ago.
not impressed yet no contact.......... anyone?
Expert:  Jeremy replied 1 month ago.

My name is ***** ***** I will assist you with your question today.

I'm an independent contractor and I don't get paid until a rating has been made.

We can go back and forth as needed to help resolve the issue you are having. Follow ups are free after ratings, so rate in confidence!

I appologize for a wait. This was in the wrong category it looks like. It looks to have just been moved from the CAT bulldozer to trucks. Not sure why it wasn't moved sooner.

To understand, you checked the cruise in the ET and it is showing you are getting the switch activation in the ECM, correct? What about the clutch? Are you getting the activation and deactivate with it?

On the 2001 379 Peterbilt, I don't think there is a parking switch. I know the 2005 is the change over year and it has one, but I don;t thingk that year does.

Have you checked the brake switch? Unplug the wire going to it to break tha circuit and then see if you get the high idel. If there is even .2 volts going through that switch, it will cut the cruise, even though it isn't enough to power the lights on. That is a big problem on the Petes with cruise issues.

_______________________________________________________________________________

You want a 5 star service and I want to provide a 5 star service. Please consider that I don't know your skill level as well as I can't see, touch, smell, hear the vehicle/machine in question. Please provide as much detail as possible and I will provide as much back.

Once an answer is provided, you should see a rating screen. Please rate my personal service to you. The ratings are my personal feedback, they are not the site feedback.

Thank you for allowing me to assist you through Just Answer!

Jeremy

Customer: replied 1 month ago.
the ecm will see cruise switches. in cat et it is saying service brake switch is on. one wire on the brake switch number 281 has votage. high idle does not work with the wires disconnected. have been diesel tech eight years in a independent shop
Customer: replied 1 month ago.
new brake switch. tried new abs module no luck.
Customer: replied 1 month ago.
hand brake released
Expert:  Jeremy replied 1 month ago.

That would eliminate that. I'm pulling diagrams up for this one. Give me just a second. Paccar site is weird tonight.

Customer: replied 1 month ago.
fuses ok
Customer: replied 1 month ago.
the power in 281 is key on power and goes away when abs module is unplugged
Expert:  Jeremy replied 1 month ago.

What about the vehicle speed sensor? You are showing a dead 0 in ET for that, no jumping, right? That can cause the high idle to not kick up.

Customer: replied 1 month ago.
voltage is about 5.6
Customer: replied 1 month ago.
checking
Customer: replied 1 month ago.
0 on vehicle speed steady
Customer: replied 1 month ago.
there is a relay that i thought was brake relay but lights work when relay is unplugged. but 281 also loses power when relay is out
Expert:  Jeremy replied 1 month ago.

That should be goo then. Only other thing on the circuit is the retarder solenoid. It does the active cruise though, not passive for high idle. It just engages when the truck is going downhill to keep the truck at the speed it needs, based on the top speed set.

Let me see if CATMAN is up. He is the truck engine CAT engine expert. I don;t think this is a chassis side issue, which is what I am. If it was chassis side, you wouldn;t be getting the signals to the ECM, which you are. That means there is a engine side issue and I will email him to take a look.

Like I wrote, this was in the wrong category for some reason and the heavy machine people tend to sleep more. We are on all the time on this one.

Let me email CATMAN and let him take a look at this. Be right back.

Customer: replied 1 month ago.
thx
Expert:  Jeremy replied 1 month ago.

I just sent him the email. He is showing online so I will opt out for a few minutes so he can grab it. He can't grab it while I am on it. He's a CAT engine instructor so he knows his way around those engines.

Customer: replied 1 month ago.
k
Expert:  Cat Man replied 1 month ago.
Thanks for asking your question. I will try and help you out.From reading your responses above. I see you have ET. That's great as it's needed to troubleshoot a problem like this.
Here is a list of all items that will cause the cruise not to work.Customer specified parameters (normal operation)
Cruise control pause switch
On/Off switch for cruise control and idle control
PTO on/off switch
Set/resume switch
Circuit for service brake switch
Transmission neutral switch circuit
Clutch switch circuit
Vehicle speed circuitPlease review and let me know if all these items are working correctly. From experience most often I find a faulty clutch, brake, or transmission nuetral switch is the cause of cruise not working.Please reply back if you need more help or have more questions. I am happy to assist.
Customer: replied 1 month ago.
ok thx only thing I have seen in ET is the service brake switch is always on
Customer: replied 1 month ago.
will check it tomarrow when i get back to shop
Expert:  Cat Man replied 1 month ago.
Thanks for the information.
I would try that first. See what happens when it's off. Let me know how you make out. Have a great night.
Customer: replied 1 month ago.
k every thing I have tried will not turn off the brake switch i think it's in the oem side not sure
Expert:  Cat Man replied 1 month ago.
Thanks for the information.
Check your input programming under configuration and see if one is programmed to brake switch. You should be able to turn it off.
Customer: replied 1 month ago.
it has pin 45 as brake switch but my ET will not change it
Expert:  Cat Man replied 1 month ago.
Ok. I would locate pin 45 on the ecm truck side harness. Then try opening it up and shorting to ground to see if the status in ET changes.
Customer: replied 1 month ago.
will do
Expert:  Cat Man replied 1 month ago.
Ok
Customer: replied 1 month ago.
hey catman if I ground pin 45 brake goes off
Expert:  Cat Man replied 1 month ago.
Thanks for the information. Does the cruise work with it off?
Customer: replied 1 month ago.
high idle works truck is in pieces can't drive it yet
Customer: replied 1 month ago.
had no high idle before
Expert:  Cat Man replied 1 month ago.
10-4. Sounds like that was the problem. Good job. Please reply back if you need more help or have more questions. I am happy to assist.
Customer: replied 1 month ago.
cruise will not disengage with brake though. would you s3nd me back to jeremy i think the problem is in chasis unless you know a way to bypass for brake disengagement
Expert:  Cat Man replied 1 month ago.
Thanks for the information. It sounds like the wire between the ecm and the brake switch is broke. I would run a new wire to the switch. It should work fine then.
Customer: replied 1 month ago.
ran jumper wire and brake was on in ET with out peal pushed
Expert:  Cat Man replied 1 month ago.
If the wires are good. You have a bad brake switch or the wrong the wrong switch. They make normally open and normally closed switches.
Customer: replied 1 month ago.
k thx
Expert:  Cat Man replied 1 month ago.
You are very welcome my friend. I am happy I could help.

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