Have a 1999 5.9L 4x4 that a couple weeks ago became possessed. For starters fuel gauge stopped working, Transmission went into limp mode and battery goes down after a couple days if I don't drive it. Installed new battery, no change, Limp mode codes were Governor Pressure Solenoid and Sensor, replaced both same codes after replaced still in limp mode. Fuel gauge will show full tank for about a minute after startup but then moves to empty. I had alternator checked it is fine. I am about ready to put a bullet in its head and call it a day. Any ideas will be greatly appreciated.

 

Check the connector on the bottom side of the power distribution center.

 

Have to codes reappeared ?

Faulty sending unit on the pump . They wear out by design . Pump is still fine , I've ran them months before finally getting tired of guessing the fuel level . New pump is really the best solution .

 

Did you clear the codes when you replaced the parts?

 

Maybe you're best to take it to a trustworthy shop, it's kinda hard to pinpoint electrical issues unless you know what you're doing.
That being said, for the fuel gauge it's most likely the sending unit, tough to tell if it's that or the cluster unless you have a scanner that can read live data.
Same with the trans, you'd need to check the wiring from the sensors to the module for continuity, which again won't tell you much without a proper scanner to read live data. You could actually have an internal trans issue or a failed module causing this.
The draw may also be a pain to find unless you have a low amp inductive amp clamp. You can try an old method Ive seed before on older cars, it may work but I doubt it.
Take off the battery negative terminal and use a single cable test light to complete the circuit, meaning clamp the clamp to either the post or terminal, and somehow attach the tip to the remaining end. If the light lights up, something is drawing. Now you'll need to pull fuses one by one until the light goes out, when it goes out you have found your draw source. Either that or you've found a module that is staying on because the test light is keeping it awake.

 

check grounds , all you can;and i have found several factory radios that have something grounded in them which causes all kinds of feedback into the puter systems

 

How was it checked? There are diodes(multiple) in the alternator that if one goes bad will create a draw. You have multiple issues so address one at a time.

 

I did clear codes but as soon as it was put into drive the codes came back

 

Auto parts store had a hand held checker and I asked if it was able to check the diodes in it and not just whether or not it was charging and he said it did

 

It will charge with bad diode just won't have that high of an output. Pull the large wire(battery lead) off the alternator and check if you still have the drain on the system.