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4Wd Light Stays On


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I would check the Vacuum lines running from the transfer case to the CAD and the 4WD switch.  

 

If you wanted you can lock the cad so it is always locked.  this way if you will have 4wd and not worry if the cad actually locked or not.  I won't hurt anything to have it locked over, and in 89 or 90 they did away with the cad all together. 

 

 

EDIT: Here is the cad fix link http://comancheclub.com/topic/17377-cad-fix-1/

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I would check the Vacuum lines running from the transfer case to the CAD and the 4WD switch.  

 

If you wanted you can lock the cad so it is always locked.  this way if you will have 4wd and not worry if the cad actually locked or not.  I won't hurt anything to have it locked over, and in 89 or 90 they did away with the cad all together. 

 

 

EDIT: Here is the cad fix link http://comancheclub.com/topic/17377-cad-fix-1/

thanks for the reply! great information

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I've done the CAD fix and I didn't like it at all you have to have your front driveshaft balanced, new u joints, pretty much everything that has to do with 4wd. I had the same problem as you and I just replace the shift motor and re ran all vacuum lines from the transfer case to the shift motor and after that it worked. If you do the CAD fix your comanche will always have the front driveshaft spinning 2wd and 4wd so it makes your truck really unstable and shakey and a lot of vibration around 45-60 mph an it's very annoying I also experienced less gas mileage so don't do CAD. Go with re running the vacuum lines and keep the stock system. They make a vacuum line kit for the cherokee on amazon fro around 30$ that's your best bet!

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I've done the CAD fix and I didn't like it at all you have to have your front driveshaft balanced, new u joints, pretty much everything that has to do with 4wd. I had the same problem as you and I just replace the shift motor and re ran all vacuum lines from the transfer case to the shift motor and after that it worked. If you do the CAD fix your comanche will always have the front driveshaft spinning 2wd and 4wd so it makes your truck really unstable and shakey and a lot of vibration around 45-60 mph an it's very annoying I also experienced less gas mileage so don't do CAD. Go with re running the vacuum lines and keep the stock system. They make a vacuum line kit for the cherokee on amazon fro around 30$ that's your best bet!

thank you! ill check amazon now.

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If you had that bad of a vibration you needed to rebuild your shaft anyhow. The CAD was done away with in later years because it is a crappy design. It will only take one time for it not to work when you need it most, when you will be kicking yourself for not deleting it.

 

Just think if you dive head first into a hole thinking your front axle is locked in. You get about rocker deep and all of a sudden you realize you are nothing more than a 2WD truck and you're now stuck. You will have to get pulled out, winch yourself out, or go SCUBA diving to fix your none working CAD.

 

I always lock them over because that has happened to me. Now I never, ever wheel alone.

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I've done the CAD fix and I didn't like it at all you have to have your front driveshaft balanced, new u joints, pretty much everything that has to do with 4wd. I had the same problem as you and I just replace the shift motor and re ran all vacuum lines from the transfer case to the shift motor and after that it worked. If you do the CAD fix your comanche will always have the front driveshaft spinning 2wd and 4wd so it makes your truck really unstable and shakey and a lot of vibration around 45-60 mph an it's very annoying I also experienced less gas mileage so don't do CAD. Go with re running the vacuum lines and keep the stock system. They make a vacuum line kit for the cherokee on amazon fro around 30$ that's your best bet!

The front drive shafts are balanced, the 4wd system is rated at normal road speeds.  my cad has been locked for a while before i swapped to a Non-CAD HP D30, I know not of the issues you where having. even with the front drive shaft removed i did not notice a difference.

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I've locked the disconnect on 2 Comanches and never had any issues. They discontinued the disconnect later on all of them. But if you have bad u-joints I'd recommend replacing them anyway. That way they won't go out on the trail or the highway and cause more damage. Just my two cents.

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If it's actually going into 2wd but the light is staying on the switch could be sticky on the tcase. Often that is also a sign of the tcase being low on fluid so I would pull the fill plug on the back and top it off. Since they only take a couple quarts, I usually go with the synthetic fluid. You could switch the front axle to a cable operated Posi-lock style.

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