Hello I’ve got a ‘99 H1 and I’m wanting to unhook the CTIS semi permanently until I’ve got time to rebuild system. Can someone please tell me in detail (I’m not a mechanic at all but trying to learn) what exactly needs to be done to safely drive my hummer without the CTIS connected and exactly what I’d need to do to disconnect it. Thanks so much in advance.

 

Disconnect the air lines at the wheel valves from the hub using a 3/4" wrench. Install plug in hole in hub with 1/4" pipe plug. Remove wheels. Buy new wheels and install. For the amount you're going to spend on new tires and wheels you could probably just repair the CTIS system air leaks.

 

Thanks for the response Ian. I’d read a post that was poorly explained but gave me the impression that the system could be unhooked, capped and wheels and tires could be driven as they are until the system could be fixed. Unfortunately I’d ignored the leak and used the compressor until now it doesn’t work, so I’d have to replace the compressor, lines, and all of the ctis fittings in the wheel and I’m just not capable of doing all of that. Was hoping to find someone (mechanic) who could replace for me but I’m in middle TN and not having any luck doing that. At this point I’m not sure I’d fix the system as it’s given me problems since the day the Hummer was purchased. Any help or other advice would be much appreciated.
Chad

 

Hey Chad. Give me a call i can explain a lot better not typing it all out.

 

That's correct you can just disconnect each tire and keep driving if the main CTIS system is leaking or not working.

All you have to do is to go to the hub and disconnect the tires individual line disconnects at each wheel and each tire will be disconnected from the system. It's a small button release on each brass T-fitting for OEM CTIS tire valves.

That's it. You can air up using the Schrader valve at each wheel. If you have factory alloy wheels then you'll need to use a screwdriver to remove the hubcap.

If you have a steel wheel with the triangle CTIS guard you can just reach behind the shield and release each valve.

CTIS isn't a big deal to fix, it's just a 100% duty cycle air compressor feeding into a solenoid/manifold set with 3 channels [front, rear, exhaust], your hoses to the geared hubs. The compressors can be rebuilt or cleaned out [OEM is Thomas], but you should do the usual electrical tests firsts, like voltage/continuity and drop voltage testing with a meter. I'd also check the fuses under the dash AND the maxi-fuse that's near the manifold to see if they work.

I've brought old CTIS pumps back to life by pulling them out of the truck and taking the end cap out, cleaning out the rust if any and checking the little contacts on the top of the plastic endcap of the compressor, sometimes a cleanup gets things working again.

If it's shot you can probably replace the compressor with a viair, just get one that's 100% duty cycle rated and runs on the same power setup.. 12v 20AMP I think. The pumps pretty low CFM rated.. less than 1 cfm or half a cfm should be up to spec and the overpressure popper valve on the manifold should be no more than 50-55 psi or it may break the guage.

Solenoids can be cleaned out by using deep socket sets. Unscrew the half thickness nuts on top of the solenoid packs, remove the solenoids and then stick a long thin wall deep socket [I forget the exact measurements they're odd ball, front/rear are one size.. maybe 33mm? and the exhaust one is a similar match to a oil pressure sending unit socket] you can then clean out the manifold that way. Don't use the small hex screws, those are dissimilar metals and on almost all H1's they're are seized together most often then not.

 

Thank you so much for the help. I’m to this point. What do i do from here? I assume that i use the Shrader valve that comes from the center? Does the quick disconnect come all the way off? It seems to be stuck here. If this is as far as it goes, do i just leave at this position and drive? Please click to view pic and let me know. You have been a huge help and i do really appreciate your time.

 

Call me, i would be happy to help. This is so much harder to type out then to explain over the phone. Its easy(and will only take you 10 min) if you have the parts you need<which you dont>.

 

Thanks Ian. I’ll give you a call tomorrow. I do appreciate it

 

...

In that picture, the truck is undrivable. It has no air.

If you have the drivers manual for the truck it explains connect/disconnect operation. On that brass fitting in the middle of the wheel, that's the valve for the disconnect, you press in on the silver tab and the valve pops out a few mm. At that point the wheel is disconnected. The value isn't actually removed from the hub, the OEM t-fitting stays physically connected together even though the system can be isolated by the silver tab.

If you wish to remove the wheel, you can remove the valve with a wrench from the center of the hub only. The fitting going into the wheel side should be left alone [unless you completely deflate the tire for safety reasons] What holds the air in is the T fitting.

As pictured the crush air line fitting has been removed, so there is absolutely nothing holding the air into the tire.

You'll need a new air line, the question mark type, and rebuild the line at this point. each end has 3 parts the fittings that go into the value and wheel, and the crush fitting that compresses the line onto the stem of the fitting. You can sometimes reuse the airlines if it isn't chewed up but there is no guarantee of a air seal.

What you can do is pick up a few tank-valves at a ace hardware.. they are Schraeder to NPT brass fitting.

You can deflate the wheel first, then completely remove the airline then install the tank valve with a bit of white pipe sealant and then you'll have a "normal" truck wheel.

They're on Amazon as Milton Tank valve, 1/4 NPT to Schraeder.

You don't need to do this if you just pop the silver tabs on the central air fitting, but if you have removed the fitting that goes into the wheel as shown in the picture, you have to fix the airline at this point or replace with a tank valve until the airline is rebuilt.

 

Replacing the damaged ?shaped air line with all four wheel valves will fix the problem of the tires going flat and you wont need to remove any other parts of the system. If you need and parts or service or just a bit of guidence we at Big Dog Offroad would be happy to help.