usrjcro11

This is describing and solveing a problem. Truck started cutting on and off going down road after starting up and going about a 2 mile. Tried shutdown override and did not help. All gauges looked good and radiator full. Truck finally quit completely. Started testing with power probe cab relay and starter relay on firewall and would turnover. Disconnected positive battery cable and was getting 12 volts on cab relay with key off on negative side. My multimeter was shipped to fluke for repairs. I said it must be a capacitor somewhere that hasn’t completely discharged. Hooked farm service truck to truck and lowboy and ran air hose to services tanks on truck and pulled it home about 2 miles because getting dark. Next day remembered I put negative firewall relay on other truck but could not explain 12 volts. Took relay off 91 model and installed on 94 model. Went to hook up positive battery cable and found problem. Crossover positive cable had rubbed on battery box and had gone to ground. The ground relay had done its job. That explained 12 volts on negative side of relay but probably few amps knowing all I had was power probe on battery. Live and learn. Simple things first.

Sorry for being late updating post. New valve corrected problem.

I will be ordering new valve tomorrow. will update when I get it in and replaced. thanks

Well you both are correct. Lines are backwards. I was just hooking to old lowboy trailer whichever way made brakes release. No color codes on trailer.Am I correct by saying no air should come out of either hose without trailer service valve pushed in? If this is correct then is trailer protection my problem with air coming out of trailer line without trailer service valve pushed in? thanks

This was problem. Truck had been sitting up for about 6 months. Exhaust line was plugged. Took exhaust line off and it worked. Thanks all that contributed. Newbie in learning curve.

I will do some testing tomorrow. Thanks all for replies. Will report back

Correct

Sorry to confuse. Two separate issues.

I knew what it was suppose to do but my air bags never purged air to assist uncoupling from trailer.

The air bags do not start raising till about 90 psi. Same time as air bag on cab starts raising.

Yes I can tell when bags are inflated after air builds up.

Will test tomorrow. Where should the air exhaust from if switch is working properly? Leveling control valve? Behind dash? Wondering if I may have a plugged exhaust line. Dirt Dobbers are bad here plugging lines. Had a international truck with vacuum assist brake. Brake pedal hard but no brakes.put new booster on no better. Found exhaust line plugged from dirt dobber. Learn expensive lesson.

I will take pictures tomorrow up and down. Noticeable difference.

Mechohaulic fully understand. Need all help I can get