If you have the newer style CTIS with electric valves, you can first isolate all 4 tires. Then bleed the system of air, press deflate while setting is on Both (Fronts & Backs) Open Hood and look at 3 valve infront of compressor. Again make sure no air is in system. Remove electric actuator from valve you wish to work on. (Just a Nut and Warped Washer holding this on) Now remove the Shaft the electric actuator was sitting on, a Deep Socket works best for this. Now be carefull as you remove the shaft, very slowly as you approach the last threads incase any air is still in the system.

Thats it. Inspect the Stem/Shaft you removed. Thats the working part of the valve. The part left bolted down to your truck is the base of the valve. The top part is spring loaded, so make sure the spring still has tension/springyness, and the teflon bottom will seat firmly to the base of the valve. Make sure the base is in good condition with no cracks or dirt in or around where the teflon will sit.

Thats It, Reassemble in reverse order.

Oh and if the spring or teflon or brass base is not in good order, a good hydraulic or hose shop should carry replacement valves or overhaul kits for air valves.

Also check the brass fittings on either side of the valve. I had a hairline crack in one this winter that was a puzzle to find. Sometimes I would loose >10 PSI overnight and at other times 2 - 5 PSI in the same time period. A spray bottle of soapy water on a cold afternoon finally found that problem, and at the time it really didn't make that many bubbles....

Frank
96 TD Wagon