M939 Front Axle Not Engaging. Low / High or dash selector.

[sburrell]

I'm troubleshooting an issue we have with a M927 that will not engage the front axle. I've been looking at the TM troubleshooting section for the front axle engagement but without a good way to attach an air gauge I've been going off of the fact that I do feel something happening when air dash switch is engaged on the air supply line to the front axle cylinder. Anyone have any experience or recommendations to troubleshoot the issue or any pictures of what the air lines are supposed to look like? I am pretty sure that I feel pressure at the interlock cylinder as well and having no problems going from low to high and back. I'm a mac user but I'm working on getting the windows software provided in the TM section to give a visual of how its supposed to work.

TIA

Shane

 

[doghead]

Site rules require a state listed in your location.

 

[sburrell]

Location listed hopefully.

 

[doghead]

Do your windsheild wipers function?

 

[sburrell]

Yes both sides. Acc air seems fine.

 

[sburrell]

Axle lock in light iluminates with dash switch also.

 

[sburrell]

I've tested for air out of the dash switch. Next suspect would be air switch actuator?

 

[stampy]

Found out I had the same problem last night. I hear it actuating but no pull. Sucks when you are stuck in the mud (in your own backyard) Of course it has rained here for 40 days and 40 nights.

 

[Suprman]

Do the wheels have to do any rotation for it to engage or is it an instant system?

 

[Andyrv6av8r]

My recommendation is to jack up the front axle with FULL air pressure and see if the front axle is actually engaging. Alot of these trucks are plumbed incorrectly at the High/Low air switch. Mine was.