ricet07 Posted April 11, 2012 Share Posted April 11, 2012 I am new to the site so I hope this is posted in the right section. I recently installed my valair clutch and after putting everything back together I noticed the 4WD light is on when truck is in 2WD and opposite when in 4WD light is off? 2H (light on) 4H (light off) N (light on) 4L (light off) complete opposite. I didnt disconnect the sensor at the CAD or vac lines anywhere besides at the connector on top of the t case and that went back on the way it came off. Also when the truck is in 2H I should be able to spin the front shaft by hand and I cannot unless the front tires are off the ground which means the CAD is locked and explains the light being on. Now when I shift to 4WD, I HAVE 4WD but the light goes off and the CAD is disengaged so is this possible?? Will the 4WD work if CAD is not engaged but t case is?? Thanks in advance guys. Link to comment Share on other sites More sharing options...
ISX Posted April 11, 2012 Share Posted April 11, 2012 This might help you out. http://articles.mopar1973man.com/general-cummins/39-transmission-systems/80-central-axle-disconnect-cad-system-troubleshooting From what you are saying I think you got a vacuum line on the transfer case in the wrong spot. You say you put everything back in the same spot but if thats the only thing you touched then it pretty well has to be the culprit. It is sending vacuum to the CAD in 2wd and causing it to engage. Now you wouldn't actually have 4wd because the transfer case is in 2wd so it would be like the axle doesn't have a disconnect like the 2002 trucks. You say you do have 4wd in 4wd though without the light being on and this doesn't make sense. The light comes on when the disconnect hits the light button in the axle so if that light isn't on then the CAD is disconnected and you shouldn't have 4wd because of the way an open differential front is designed. The right side will spin at the CAD and the left side will do nothing, like how a car with one tire on ice will spin that tire and the other tire on pavement won't do anything. If you jacked it up and put it in 4wd then the left tire would seemingly be locked to the driveshaft and seem like it was in 4wd but in actuality it would never be driven since the CAD is disconnected. 1 Link to comment Share on other sites More sharing options...
Administrator Mopar1973Man Posted April 11, 2012 Administrator Share Posted April 11, 2012 I agree with ISX it sound like a vacuum issue... Link to comment Share on other sites More sharing options...
ISX Posted April 12, 2012 Share Posted April 12, 2012 I thought about this some more and if I were you I would take the vacuum splice 4 way adapter thingamabob off the vacuum actuator that is on the transfer case. Then unscrew the actuator so you can see the thing better and hook the 4way thing back up and start the truck and you should be able to just push the button on the bottom of the actuator with your hand. Just draw a line on the 4 way and actuator so you can hook it up the same way it came off because I don't remember if pushing the button is 2wd or 4wd. So you would press the button and see if the 4wd light comes on. Then look at the plug and see if you can rotate it since you want the opposite to happen meaning when you press the button the light should turn off. Again I don't remember which position engaged the CAD, I just think you should be able to take it out and hook it up the same way and then possibly rotate the plug to make the opposite happen. I think it might be on there wrong. Link to comment Share on other sites More sharing options...
ricet07 Posted April 12, 2012 Author Share Posted April 12, 2012 Sorry guys looks like I was over trouble shooting this the whole time. When I did the clutch I removed the lines from the top of the t case and swung them out of the way. Well I pulled the red line apart and had vaccum, pulled the black line, no vaccum. Turns out I pinched the hard line when swinging it out of the way but the retainer clip was covering it. Replaced the line and everything works as it should. I guess it had enough pressure to put the cad into 4wd and then no vaccum to disengage it just enough play to make the light go off. Thanks for the help. Link to comment Share on other sites More sharing options...
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