Rick01

I have a 2016 mack granite dump truck. I need air connection for tag trailer. The truck has the red knob in cab. The 7 pin wire connection is at the back of truck from factory but never used . The truck was originally ordered equipped for tag trailer but has never been used. How do I identify where to connect the air lines ?

Thank you for your help. I will take it to the Mack dealership .

Please help. I called the Mack dealership and no help. 2002 Mack RD688S with e7 350 engine. For some reason today my idle rpm’s are only at 400 to 500. Allison automatic transmission. The truck runs great it’s just idle problem. It was about 650 . Thank you for any help

I hope I am able to get to all the airlines. There is no room from under the hood. I think it’s going to be very tight unless I can take the floor pan loose and get to the needle valve

My truck is 2002 RD688S. I hope I have the small pan that foot valve bolts to.

Thank you for replying. I am going to try to repair today.

Yes sir. I have looked at the valve under the hood and it looks near impossible to change some of the air lines unless the floor pan is removed .

I sure hope I have that small pan under foot valve. Is it possible to remove the little pan and the pedal and valve will allow enough room to replace all the air lines or is that wishful thinking

Thank you for replying. I will remove the floor mat and then hopefully I will be able to tell more about it. I have a new foot valve and pedal but not floor pan. I hope it’s something I can fix. If I had the money I would have had the dealership fix it. I just got my truck back from them with a 5000 dollar invoice for a new manifold and all new epu bolts.

Thank you for the information. I was hoping maybe if I can remove the floor pan with foot valve on it I might have room to move one air line at a time .

They said the pan is bad. It looks to me like the aluminum foot valve is broken around two of the bolts . I can’t tell exactly tho without taking it apart.

The pan has some rust. I will hopefully be able to repair this. The truck is excellent. Only 120 k original miles. Is it possible to Mount the new foot valve to the pan before bolting the pan down. There isn’t much room to connect all the air lines

2002 rd model.

Thank you guys for responding. The truck is a 2002 RD688S. The pan is not rusted thru but they mechanic at the dealership said the pan is bad.

I had my truck in the Mack shop for some repairs and wanted them to replace my brake foot valve. Was quoted 2600 for a floor pan. I couldn’t afford it on top of the 5000 repair bill. Has anyone ever replaced a drivers side floor pan ? I am going to try and do this myself but don’t want to make a mistake that will have me shut down. please advise me on this project . Do the pans just bolt in or does it require welding. Two bolts holding the foot valve are broke and the pedal is loose thank you