i half Edit fixed a boost leak on my truck today then about 2 minutes after driving the tach dropped to 0 for about 6 second and the check engine light came on. (truck was running fine when tach dropped) just wondering if someone has a smarty i can pull codes with or if it makes more sense to drop by the dealer. thanks

 

Just turn your key on and off 3 times. Start in the off position and on the 3rd on.....leave it there and the odometer will spit out your codes.

 

That only works on trucks newer than 99.

I'd suspect its a crank position sensor. Did your lift pump shut off at the same time? Parts places usually have code readers, call them up and see if you can borrow one if no one in E-town has a smarty.

 

my bad the alternator went up in smoke yesterday im asuming that was my problem thanks

 

light came back on with new alternator and i loose my tach once in a while when tach is down the motor will get very loopy around 1000-1200 rpm, kinda same as letting the clutch out quick on cold motor.

any ideas thanks

 

sure sounds like Crank position sensor like tate said, if the computer doesn't think the engine is running then it won't turn on the Alternator, and the tranny will shift funny.

 

Yup, sounds like the CPS...

Look here Kenny:

http://www.dodge-diesel.org/articles/cps/ckp.htm