I've been having an issue with the Tachometer not working I've written in here before was told a couple areas to look on the truck for but can't find where to find my old posts.

Anyway I know I have a ground issue when I jiggle a wire here or here or even here the Tach will jump up to norm but if I shut the door or whatever at the time it disappears or better yet when I finally think I've got it two minutes later gone (the connection).

Here's what I've done I checked and regrind the area for a good connection
Passenger side from backside engine to body/passenger battery-negative to frame/driver battery-negative to frame/checked the starter wires/remounted the Tach/ran a scanner on engine shows Tps is good and positioned right/Tach sensor brand new/ Brand new gear shift w/ the 3 wires/

So all you folks what are your idea's? Or better yet explain how to make another ground inside your cab from your wire cluster (sorry don't understand)

And what's more frustrating it worked for the last 2 months without a flicker but now all of a sudden can't find it to save my #^%

 

Shouldn't the battery grounds be mounted from the batteries to the engine and then there should be a ground from the drivers side head up to by the miper motor and another from the bottom of the engine to the frame. I guess it doesn't really matter how the grounds get to the frame and the cab but thats how my truck is anyhow. i'm actually gonna upgrade the ground from the engine to the frame with some 1ga cable. I don't have a tach on my truck so I can't help ya there. What is your truck??? TPS on a diesel??

 

On my 94 the right battery ground to the block and then to the frame right under the lift pump. Left battery ground has wire from battery clamp to body around the radiator support. Another ground from body to frame at the engine cross member on passenger side. Thats the ones I've seen so far.

 

Thanks guys I will retrace all the wires again the one behind wiper is a new one for me.
And a TPS is Throttle Position Sensor around 46$ at Napa

 

I thought I had posted the truck currently working on In-laws 94' F250 IDI Factory Turbo 7.3 Diesel w/ the E40d Tranny 280k miles (tranny's been done 3 times)

 

As trucks get more and more plastic used in them, the manufacturers are all using the minimum amount of grounds to get electrical connectivity through out the body.

Those ground straps work just fine, for 10 or 15 years, well over how long they wish we drove our vehicles before trading for a newer one.

Rust and corrosion will render those minimal grounds usless given enough time, and many grounds actually get left unhooked when something gets serviced.
If one ground fails or gets left unhooked, now the load it normally carries gets transfered to another ground hopefully, and hopefully the load is not more than it can handle.

The main battery grounds both go to the engine block, but the motor mounts and transmission mount have the path to ground the body and frame interupted.

The main cab ground was off the rear of the engine to the firewall, usually near the wiper motor.
Yes there is also usually a ground to one of the front fenders, but that has to rely on a connection through a couple fender to cab bolts.

It's not that hard to add a ground from the battery to the fender and then on to the cab and possibly on into the cab under the dash.

Same thing for the bed lights and trailer plug if you have one.
A ground wire from the battery to the rear of the truck that picks up the trailer plug and bed light grounds instead of going through the frame can get rid of many issues.

More than once I have read of brake/tail light grounds causing problems with the torque converter lock up on the transmission.
Most people would never consider a tail light ground having anything to do with a transmission problem.
However the way an 1157 bulb is constructed, if the ground for the bulb is lost, parking light power tries to get to ground through the brake light wire, which the transmission sees and thinks you have your foot on the brake and unlocks the torque converter.

Moral of the story, grounds or lack of grounds more exactly can have strange results in places you would never expect.
Replacing the stock grounds, checking the condition of the connections or adding a few more is never a bad idea if you are having electrical problems.
If you are not having electrical problems, a little time and a few more grounds can mean you won't have problems, which always happen at a bad time.

 

Yeah, what he said!!!

 

Dave Sponaugle's That was an "AWESOME" write up and explained a lot. Thank you
I will start with the grounds from the back and work my way up to batteries

 

Grounds are in place or so I think I began to find more grounds inside the cab as well. Next question for why I even began this journey the Tachometer not working right , Last night my teenage son and I went looking for why the Tach's not working we move wire's,replaced the TPS with another new(getting quite expensive) we have a recently new Tach sensor, New gear shift with those three wires The damn thing will just start working out of the blue then when you start moving wires around to isolate the area it keeps working but wait it gets better when you accelerate then decelerate and then needle comes down it's gone the Tach that is.. Could the PCM have anything to do with it.




I think some Dupont will work just fine!!!