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CaseFace, Mechanic
Category: Heavy Equipment
Satisfied Customers: 303
Experience:  22yrs Auto,Truck,Tractor Trailer,Heavy Equipment, Industrial Truck,Forklift,Motor Coach,Tour Bus
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I drive a 2007 Vovlo 780 heavy truck...Autoshift transmission

Customer Question

I drive a 2007 Vovlo 780 heavy truck...Autoshift transmission traction control abs...I have lost the rear most axle power,,only the main drive axle is if I am in a parking lot with even small potholes and I stop over them then try to move only the front axle will spin...The power divider does not have a switch other than the TCS switch which used to work but not anymore...My driveway has a low spot in it then slight upgrade and I used to be able to hit the TCS switch and drive right out,,,not anymore..
Now I looked over the power divider and I do not see any wires going to it nor do I see any air lines going to it so either it has a wire running inside the axle tube from the wheelspin sensor or it is centrifically opperated I am GUESSING...I do know that if there was a INTERAXLE switch on the dash there would be a airline going to the actuator and all I see is a plug where the line would go....However the TCS switch used to make it work.
Submitted: 7 years ago.
Category: Heavy Equipment
Expert:  CaseFace replied 7 years ago.
It has been awhile and no one has answered so I will try to help.

Sounds like you could have broken an axle, pull them out and check.

The tcs works with the brakes to stop the spinning wheel so the other will grab,
it will use the Abs Exciter Ring to detect the wheel spin.

Expert:  CaseFace replied 7 years ago.
I didn't see the part that the Drive Shaft wasn't spinning.

I'll be back with you.

Expert:  CaseFace replied 7 years ago.
I have to opt out.
Customer: replied 7 years ago.

Hi Steve(CaseFace),

Just a heads up,,I was a C-141B Crew Chief in the Air Force Then Drove Truck for 5 years b4 going back to turning wrenches for B&T Trucking then 2 more years of Trucking then went to Pep Boys and became a drivability mechanic(started as a alignment tech then they sent me to drivabilty school since I love electronics) so what I am getting at is I have a logically and Mechanicly driven mind...The problem is this Truck is a company truck and very few of the Mechanics in the 7 termanals we have will listen to the Driver(and Lord knows I know why,lol) Back to the subject...I went to the Eaton website and seen how the limited slip style axle interlock works...yeah "limited slip"no longer can we flip a switch to make the rear axle drive,grrrrrr...all the TCS switch does is turn off the TCS so the engine will not retard when the wheels are spinning,,hmmmm.. So I told the mechanic and service writer to please just pull the drain plugs on the rear differential and the Power divider or Axle interlock Housing (which ever its called) and I bet you there will be chunks of metal falling out...They refused to do so and said they know there is nothing wrong with it..SO all I can do is hang onto your answer and when it finnaly gets PROPERLY troubleshot or towed then I can hit accept your answer...Till then we are speculating...I did suspect a broken thrushaft...But now I am guessing a bad limited slip clutch assembly inside the Power divider..It would be so nice to see it go on a drivetrain driven Dyno so they could see that the rear axle is dead and the Primary axle is the only one working...Thanks anyhow and again,,I am saving these emails so I can accept your answer so you can get paid..I wish it was my truck and not a company truck so I could tear it apart myself,,but I would get fired,,,grrrrrrrr...I would pull all 4 axles out and pull the drain plugs...I also wish I would have let the Volvo dealer fix it verses the U.S.xpress shop..But when it was at the Des Moines Volvo shop I had already been down a week for a Major Brake issue(parts wait)they claimed they knew what the problem was on the rear axle also but I would be down longer waiting on more parts..They said take it to one of our shops and let them do it,they might have the parts on hand......Suuuuure,,lol..

Thanks again and keep watching for an accept..

God Bless


Expert:  CaseFace replied 7 years ago.
As you being a mechanic and worked as a mechanic you know what the deal is, you must see what I have seen and it is people being hired as mechanics that are not or never were meant to be. They want to be mechanics but can't comprehend anything, I'm sure the ones that would stick out in your mind are the ones that are constantly turning nuts and bolts the wrong way.

When I here a mechanic say they are all like that or there is nothing wrong then they either have no idea how it works, or have never repaired a problem like it or can't figure it out.

It should be easy enough for them to see that the driveshaft isn't turning and to drain and check the fluid as you say.

All they really have to do is jack it up off the ground and put it in gear and run it to see
that it is not working.