1999 Dodge Ramcharger Altitude shifting problems

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1999 DODGE RAMCHARGER

1999 Dodge Ramcharger Four Wheel Drive Automatic 105000 miles

I have a 1999 Dodge 2500 V10. I take it to Colorado every year. It will shift fine but when I get to 10,000 feet and shut the truck off then restart the truck I only have first gear. Then I can drive and coast back down the mountain to 7,500 feet shut the truck off and restart I will be back to normal.

This has happened two years in a row. Once I am off the mountain the truck runs great.

I had the transmission and transfer oils changed when this happened the first year. But the problem continues at high altitude.

Some people have suggested it is a computer problem.

Any info would be appreciated.

1 Reply

CARADIODOC

MECHANIC
33,873 POSTS

The MAP sensor monitors load on the engine by measuring engine vacuum while it's running. Before the engine starts, it measures barometric pressure. Normally the problem would be the opposite of what you have. As you go up in altitude, the MAP sensor goes out-of-range based on its memorized barometric pressure. Turning the ignition switch all the way off for a minute, then restarting it will cause it to take a new barometric pressure reading. From then on, engine vacuum will be "in range".

Your transmission is computer-controlled, and the MAP sensor reading is used, in part, to determine shift points. I would suspect the MAP sensor was not designed to work that high since it's really not considered a "normal" condition. Ask the dealer if there's a different MAP sensor for high altitude use.

Caradiodoc