1500 318 OVERDRIVE LOSES VACCUM

1995 Dodge Ram

Tiny

tryan

August, 13, 2006 AT 10:28 AM

My truck all of a sudden after 112000 miles xmission got week and overdrive would not downshift on incline. A/C will shift from vent to defroster going uphill I assume low vaccum pressure. Had xmission rebuilt truck locks up and takes off great but still has overdrive symptoms. Is this a vaccum problem or a xmission shift sensor or was my rebuild done wrong.

4 Answers

Tiny

dakotabs

August, 14, 2006 AT 7:33 PM

Check your intake manifold gasket for vaccum leaks

Tiny

tryan

August, 14, 2006 AT 8:17 PM

What is the unit underneath the battery in a 1995 dodge ram 1500 has a cable run from the carb arm and vacuum lines in the dash I assume for A/C control I found that my steel cable from this unit doesn't move on its own but moves in and out by hand. Should it be pulled into the unit with tension and open when the carb opens.

Tiny

Mikeybdman

August, 14, 2006 AT 8:40 PM

Kind of hard to visualize the items you are talking about. The vacuum line that goes in side the car is to drive your air doors for your defrost, and vents. This vacuum line should go from the intake to a vacuum tank. In that line should be a check valve. Then from the tank to thie inside of the vehicle. The check valve is to keep a vacuum leak inside the truck from causing driving problems. When you described before the vents changing when you went up a hill, makes me think that maybe that check valve has gone bad, and maybe you have a vacuum leak.
The cables that go to your throttle body should only be two. A crusie conrtol servo cable, and a throttle cable. The down shifting is all done by computers.
I would make sure that vacuum system going to your inside is in good shape, and I might even disconnect it a plug the hose to eliminate that as a problem. Then see if your truck runs good. If it does, then find the problme in that vacuum system. If it doesnt make a difference, then place a vacuum gauge on that line and see how you vacuum is. It should be around 18-19 inches and steady at idle. If you have a large leak, then it should run rough.

Tiny

BarmarAZ

April, 30, 2007 AT 10:02 AM

" what is the unit underneath the battery in a 1995 dodge ram 1500 has a cable run from the carb arm and vacuum lines in the dash" This is the Cruise Control Servo Unit. If your cruise control doesnt work it need to be replaced. It could have a vaccum leak internally on in the line that feeds it.

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