remove the cig lighter also then try it

 

Well I changed the fuse and it still won't work. I have, though, narrowed it down to it not working when the engine is on. If i have the key turned on, but the engine off, gauge works perfect. Soon as I crank the engine it stops working.

 

ttt.....

 

Idk what to tell yoou dude = (

maybe you need to probe it with a test light with key on/off or something.

 

If your truck is tuned, maybe the tuner fucked it up or locked it if you can do that, that is...

 

Nope, it won't do that

 

Nope, untuned for the time being

 

I just went through the same thing with my truck. Take the cig. lighter out and make sure the fuse is good. And then check the orange wire on the aldl port. Its the power wire.

 

Did all that. Works perfectly until i turn the engine on

 

Just throwing this out there and I don't even know if its relevant or not, but the first time I wrote a tune to my 4.8 truck I had to do a write entire instead of a write calibration only.
I mentioned it to a local tuner and he said it MAY be because there is no 4.8 OS so to speak, so more than likely I'm running a 5.3 or 6.0 OS.
Maybe your gadget is acting up because its looking for one thing but finding something else? What motors were the other trucks you had it hooked up to?