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T2000 Air Line Mystery - Need Expert Advice


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My 2002 T2000 conversion has restarted after a protracted delay. Removed the tandems and replaced them with HAS230/23klb single. Unfortunately, my airline labels did not stand the test of time. The old nylon airlines were in the process of being replaced before work stopped. When work restarted, I took on a young inexperienced assistant. Unfortunately, my assistant was a bit too eager removing the remnants of the old lines, making after the fact identification problematic. I am having difficulty resolving the correct connection of four airlines.


Mystery Line #1 - Silver 5/32" line connected to Port 83-2 at the Driver Side Airline Terminal in the Engine Compartment. This line cracked and has broken into multiple pieces. I believe this line is the interaxle differential lock control and terminated between the tandems. Can anyone confirm this? If not, what function does it perform and where does it connect at the axle end of the line?


Mystery Line #2 - Violet/Purple 5/32" connected to Port 110 at the Driver Side Connection Terminal in the Engine Compartment. This line also was brittle, cracked and broken in multiple pieces. Not really sure where this line went. Too many of the pieces were gone, with no stub remaining at the other end. What function does this line perform, and where does it connect on the other end?


Mystery Line #3 - Violet/Purple 1/4" line connects to an electronic module mounted on the upper air tank, located on the passenger side. This line appears to run and terminate roughly at the tandems but it is not obvious where and to what this line connects to. The line is approximately 8 feet long. What function does this line perform, and where does it connect on the other end?


Mystery Line #4 - Green 5/32" line connects to the electronic module mounted on the upper air tank similar to Mystery Line #3 but Mystery Line #4 is only 24" long and is floating free in the dryer air line harness located at the rear of the transmission/cross member. Is this line supposed to be floating in the dryer air line harness? The green line looks like it could of been connected to something but it isn't obvious what the connection is. There are no other 5/32" lines in this harness, nor any other floating (unconnected) airlines at the rear of the transmission/cross member. What function does this airline perform? Where is it supposed to be connected? This line was very clean compared to the other lines it was harnessed to. Is this some sort of vent line for the electronic module? What function does this electronic module perform?


The attached picture shows the electronic module and Mystery Lines #3 & #4.


May have to visit the local KW dealer or find a similar T2000 to look at.


Does the HDT expert collective have any insight on how these airlines are connected or their function?


Appreciate any and all help/advice.




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What year you got, going to take some work to help you here. A copy of the air system schematic

would be most desirable here for sure. You very well may be able to get some help from KW in that regard.

On that silver line, checked mine and yes it goes to the diff lock. Because you now single that one should die.

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True that is. Another one is the line that unlocks the Jost hitch slider too. I just taped the suspension for my ET.

A do over would have me use one of the lines with a switch to dump the air, I still might change it, we will see.

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83 silver is interaxle diff. It goes to the aluminum anchor block on the rail, then drops down to the axle with the rubber hose.


110 purple goes to the inversion (dump) valve just before the leveling valve. Or it goes to the dump port of a modern day leveling valve.


731 purple goes from an airbag line to the A/D converter. It runs your suspension pressure gauge.


The extra green line is a vent line. It keeps the AD converter from reading wrong at altitude changes.


The AD module is what puts the gauge signals onto the 1708 bus so the gauges can read it.


Running an air hitch from the dash acc manifold, thru a switch, then thru a firewall manifold with a 5/32 hose I'd imagine is a bit risky. I'm not sure it can supply what is needed fast enough.



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2002, thanks for confirming my suspicion about the silver air line.




My single has an air locker. I plan on repurposing the silver line to control it.




I have the Bendix handbook, the Air Brake manual from Manitoba Insurance, and the Air Brake Book, 8th edition from CCJ. They are all decent general overview resources. Unfortunately, they don't get into T2 application specific details.


Compressed air is also used to control/drive a variety of HDT functions. I am currently thinking that the lines/module that I am interested in may not be air brake related.


Any T2 owners up for taking a look under their T2 and tracing the connections of these lines down?


Local KW dealer is good for parts and new trucks but supporting data for older trucks is not their strong suit.


Thanks for the help.



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