My truck bucked at me friday and as it did this I noticed the tach not working right, check engine light came on and ran fine the whole way home.

I pulled the codes yesterday and to no surprise they are crank position sensor codes. P0336 and P1690.

I know I'm going to have replace it, but is this something that will leave me stranded? If it is the truck stays parked till I change it.

 

You don't say which truck you were driving but I see a 96 in your signature, my 96 is doing the exact same thing (check my posts under 12V Engine and Drivetrain). I have checked all connections I could find, installed a new crankshaft position sensor (last week), tried a different PCM and am currently checking and cleanining ground connections. So far nothing has fixed the problem.

Will it strand you? If the tach quits completely the PCM will not send a voltage to your alternator so you will lose battery charging.

I've searching through a lot of posts on theis site and it is clear that phantom electrical problems are fairly common (12 and 24V engines). If anyone has an answer I would sure appreciate hearing it.

I don't believe the problem is associated with the tach itself, since the check engine light comes on and the charging quits when the tach drops to zero I assume the fault is somwhere ahead of the PCM and the tach quitting is only a symptom of the problem.

 

Sorry, its the 24 valve, I know the sensor is behind the starter.

 

Drove mine home this way and it never started again until I replace the sensor.