Archived Wacky Tachy, Shifting trouble, Check engine/gen

[osbornegs]

1996 Dodge Ram Diesel automatic transmission. I just had the transmission and transfer case overhauled. I had to get the truck back so I could get back to work. The transmission guy wanted to hold it longer but I couldn't wait. So I got onto the highway and the truck would not go past 50 MPH (without holding the pedal to the floor and winding the engine out all the way). The tachometer would go from zero to well under 1000rpm intermittantly or jsut go to zero. Somehow I got the truck to get into overdrive and set the cruise control as long as I was going 50 (so the rpms would be low and I would get better mileage). The engine warning light and gen warning light usually comes on around 40mph and at start up. When the tach works, it is wiggly. The charging indicator rarely goes above 14 volts. And it seems the truck only works in third. Shortly after leaving the transmission shop I pulled over on the highway to check to see if any fuses were burned... I noticed the 120amp alternator fuse was blown. I jumped it, but that didn't help much. The trans guy replaced the speed sensor, and TPS as well.



I am guessing that I need I new PCM, or there is some wire that needs a 'fixin. I have read threads about cleaning contacts and checking grounds which is what I am going to try next.



I replaced the alternator and fired it back up. At first the tach seemed ok! It began to charge at a little above 14 volts too! Hurray I thought... time for a beer... But then, as I drove it, the tach began to fall, and the charge indicator slid down.



I checked the codes and I get 12... no codes. Good advice greatly welcome...



Thanks.

 

[zstroken]

CHeck the crank sensor wiring. And the crank sensor placement.

 

[osbornegs]

Fixed!

As per a thread I had read... I adjusted the engine speed sensor that the transmission fellows installed and bam... that was all it took. End of problems. No more tachometer or charging meter fluctuation problems. Shifts correctly and goes into overdrive on the freeway. Thanks all...