Yesterday as I was trying to get home from work I was traveling about 40-45MPH and decided to hit the O/D off button to keep the truck from locking up before a hill with traffic on it. When I did that I lost the Tach and ALL of the lights on the dash flashed and then went off. The speedo, volt meter, oil pressure etc. still work but now I have no tach at all. To make matters worse, it seems that the thing did lock the torque converter or something because it feels REALLY sluggish when trying to take off. I did manage to get the truck about a mile and a half to the house but even after checking all the fuses and resetting the ECM by unplugging the battery I have no tach and I'm sure it's stuck in lock mode or something. Since the diesel has no ignition coil, where does it get it's signal for the tach and if this sensor dies will it cause the ECM to freak the tranny out? Any help is appreciated as this truck is my only transportation!

 

Does it start? There is a sensor on the crank at the front pully for doing the tach, you could try to clean the connection but since it happened when you pushed the OD button I would start looking there..

 

first off we need to know what year truck are we talking about. fill in your SIG. 1st gen 12V,2nd gen 12V, early 24v, HPCR? different truck have different electrical parts