Engine/Transmission (1994 - 1998) Questions about tach on 94

[DieselNut2500]

I have a 94 2500 2wd regular cab. I just picked the truck up and the tach doesn't work. I read some where else that the tach, alternator, ac, and the torque converter are all related some how. Now I know this alot to ask in one post but here goes. The volt gauge in the truck is only reading 12 volts, the trans shifts kind of hard on the 1-2 shift for a rebuilt stock trans, and no tach. I was wondering if all of these things are related and where do I start with trouble shooting the tach. What is the procedures for checking the components related to the tach. Thanks for any help.

 

[Missouri Mule]

DieselNut2500, when the tach is not working it usually the Engine Speed Sensor, located above and left side of vibration damper.

When it goes out it usually knocks out the tach,voltage meter,and overdrive sometimes a/c and speedometer.

It mite be your ESS but then again it mite be three different things.



The ESS sends a signal to ECM which sends it to the Tach it uses the data from the ESS for overdrive use (shifts). The ESS activates the Auto Shutdown relay which sends line voltage to the EVR (electronic voltage regulator) which determines alternator output from the line voltage and batter tempature readings sent to it by the battery temp sensor located under the driver's side battery tray.



I would have your tach checked out,alternator,TPS(if you have auto trans) Throttle valve cable.



You can also check out the ESS by checking it at the connector. (Wires: violet/wt= 5 vlt supply, grey/blk =sensor signal/blk/light blue= ground. )