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vipertech763, automotive technician
Category: Dodge
Satisfied Customers: 1854
Experience:  gold certified, dodge viper certified
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2001 Dodge Ram 1500 4X4: engage..indicator light..the linkage and all

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I have a 2001 Dodge Ram 1500 4X4. The four wheel drive will not engage and the indicator light does not come on. Checked the linkage and all is OK. What have I missed?

Good morning,

Here is a discription of how the front diff. locks into 4x4:


The shift motor receives a vacuum signal from the switch mounted on the transfer case when the vehicle operator wants to switch from two wheel drive mode to four wheel drive mode, or vice versa. When this signal is received, the shift motor begins to move the shift fork and collar within the axle housing. In the four wheel drive mode, the shift collar connects the axle intermediate shaft to the axle shaft to supply engine power to both front wheels. In two wheel drive mode, the shift collar is disengaged from the intermediate shaft and the intermediate shaft is allowed to free-spin. When the two shafts are disengaged, the load on the engine is reduced, thereby providing better fuel economy and road handling.

Here is a picture of the vacuum actuator and its location.

And here is a picture of the vaccuum lines from the transfer case to front diff.

I would recommen dwith starting with checking vaccuum at the proper locations. LEt me know what you find and I will help you further.

vipertech763 and 2 other Dodge Specialists are ready to help you
Customer: replied 10 years ago.
Where is the vacuum generated? I found a couple of broken vacuum lines in the engine compartment. Used piece of rubber hose to reconnect the broken vacuum tube on the passenger side. I believe that this controls the heater switch selector. The other one appears to be broken at the base of the intake manifold. Not sure how to repair.
I we do some checking, it may take some time. Make sure the switch at the transfer case has vacuum. If not then try to follow the lines up. Most of the vacuum lines start at the intake manifold. On both the right and left sides about half way back just above the fuel injector rails. I will see if I can find more info, may take a short while.
I have been checking an havent seen any thing in where is comes from. The best way to find out is by you emmission label under the hood. It should have the vacuum line lay out. I have been trying to find an actual vehicle I can check it on, I will keep looking in the mean time.
vipertech763 and 2 other Dodge Specialists are ready to help you

I havent found a vehicle to varifiy it on yet, have you found the issue yet? Let know.

vipertech763 and 2 other Dodge Specialists are ready to help you
Customer: replied 10 years ago.
Reply to vipertech763's Post: Found the broken vacuum line above the transmission. The source of the vacuum is on the passenger side of the intake manifold. Repaired the vacuum line and 4X4 is working well. Thanks for the help and follow up.
No, Thank you.