M1083 Differential Lock Relay

[Oski1042]

So I just replaced the fan clutch solenoid on my M1083 truck. Unlike the M1078 it actually two solenoids ... one for the fan clutch and one for something called the "differential lock relay". Unfortunately I can not seem to find a description of exactly what it does beyond what it is called. Any guidance would be appreciated.

 

[Third From Texas]

Wild guess here would be for the Mode activation, but dunno.

Don't the 5-tons have a dif lock not found on the 4x trucks?

 

[Oski1042]

My assumption is that this engages when I go into "mode" setting . Next time I fire up the truck, I will listen to see if there is any purging going on.

 

[coachgeo]

yes in mode that air valve switches and activates the air locker that locks the middle axle and rear axle to be locked together. (aka there is a differential sitting sideways between the pair of rear axes..... this locker is in that differential.. NOT in the axle's differentials. Neither of the pair of rear axles have a locker)

 

[coachgeo]

yes in mode that air valve switches and activates the air locker that locks the middle axle and rear axle to be locked together. (aka there is a differential sitting sideways between the pair of rear axes..... this locker is in that differential.. NOT in the axle's differentials. Neither of the pair of rear axles have a locker)

btw- @Ronmar posted a valve you could use for this and/or for replacing the air valve to switch the engine cooling fan.

 

[simp5782]

We call them an axle interlock valve. It uses just uses power to engage it. I would delete it and use a standard flipper valve like every other semi uses. This way you can engage it even when not in low range.

You should he running with the front tandem interlock anytime it's slick. It doesn't hurt it even when running on dry pavement.

 

[Oski1042]

You guys always amaze me with your wealth of knowledge! Thank you.

I did end up running the truck and listening for what happens when the mode button is engaged. About 5 seconds after disengaging the "Mode" button there is a purge of air.

Also in case some one with such a dual solenoid is wondering .... the rear valve is for the fan clutch - forward one is the differential.

Thanks again you guys!

 

[chucky]

And where might i find these solenoids on the truck ? Behind the passenger kick panel ? I dont remember seeing anything like this except behind the kick panel .

 

[Ronmar]

And where might i find these solenoids on the truck ? Behind the passenger kick panel ? I dont remember seeing anything like this except behind the kick panel .

Yes, behind the passenger side panel, all the way over under the dash to the right…