I went to the marina today to take my boat out for it's maiden voyage after putting in a new transom & floor. I was backing down the ramp and thought it would be a good idea to put it in 4 wheel drive but it wouldn't light up the indicator. I went ahead and launched the boat and parked the truck. While traveling to a parking spot I tried 4 high and 4 low but no luck. I don't know where to begin troubleshooting this. Any help would be great!

 

Did the transfer case actually engauge 4 low gearing with no front axle bite or it wouldn't do anything period?

 

It went into low range but there wasn't any indication of the front axle grabbing.

 

I would look at the CAD vaccum lines on the front axle, make sure they are all connected at both ends.

 

Wouldn't the truck run funny if there was a vacuum leak?

 

It might not be leaking...The CAD collar inside the axle tube could be stuck and not actuating.

 

As for a vacuum leak, diesels do not produce vacuum like your bb Chevrolet, they have pumps that run off of the motor to produce vacuum for all of the vehicles systems that require it. So no it wouldn't run any differently.

 

I,ve seen where the steel part of the vacum line is plugged full of rust. If everything is connected try running a rubber hose in place of the steel line and see if that works, if it still dosn't it's probably the actuator.

 

vaccum 4x4 is a joke good luck hope it isnt the acuator dude

 

If it is, time for a posi-lok cable