Engine/Transmission (1994 - 1998) tach quit working today while I was watching it

[JWaters]

Well the tach started going up and down today while I was watching it and then it just quit. Went back to "0" and every now and then it would move a little and then go back to "0" . What do I need to check first? This is the first thing to go bad on my truck... hope it is not costly.



thanks for you help

 

[gcorron]

WJ

The first thing I'd check would be the speed sensor on the crank balancer. I put mine back on with too much gap, and the tach did not work. There are some other signs as well, but right now I only remember the tach.



I'll check the manual and see if I can remember all that does not work if someone else does not reply shortly.

 

[K5IP]

Mine did the same thing. The connector was loose. Just follow the wiring from the tach sensor at the top of the flywheel and you will find a connector. Mine was held together with a nylon tye lock strap. I opened it up, cleaned it out and wired it back again and all is well.

Rog

 

[DSiemens]

I've experienced tach, speedo, a/c and charging system loss all at the same time. Cummins keep on running fine. The problem was the wire connector that K5IP talks about, the crank shaft position sensor. The signal from this sensor was not reaching the computer. So, the computer was never turned on.