I'm having troubles with my truck, I can't get it started right now. So I'm trying to go through a do some trouble shooting. One code though the truck is throwing is a P0193, I got a rail pressure gauge in the mail today ,but it hooks up electronically too so that not a lot of help. I was just going to replace the sensor, but what has thrown me off is that I hooked up the electronic rail pressure sensor and it pegs out, which makes sense because the truck says its reading high too. But when I unplug the harness from the sensor then try and crank the truck the gauge still pegs out. I would think it should just read 0, since its not hooked up to the sensor. which this kinda makes me believe something might be shorted before it gets to the sensor? Whats your guys thoughts? Thanks

Possible wiring fault?Defective gauge?

Possible wiring fault? Defective gauge?

I don't know guess anything is possible. I follwed the manufacturs wring exactly. I been doing some trouble shooting, checking for a short or a open somewhere. In the process of rouble shooting I pulled the harness going to ecu while ohming out some wires. hooked everything back up now I got a P0122-THROTTLE POSITION SENSOR VOLTAGE TOO LOW,along with the other code. I'm at my wits end, really don't even know where to go from here.

What kind of gauge?

Autometer Rail pressure gauge

--- Update to the previous post...

I'm kinda thinking it might be the ECU, I found the factory flow chart on diagnosing the pressure sensor and after going through all the steps it points to replacing the ECU. Also I just bought the truck a month or month and half ago, who ever had the truck before put big front grill guard and it looks like they did plenty of welding on it, so maybe that shorted something in the ECU? I also spoke with software engineer that writes apps to talk to cars to pull codes and look at PID's and etc. I did a snapshot of what the computer was sending me, he says something isn't right like the truck isn't communicating properly. I might try out a new wiring harness first.

--- Update to the previous post...

Anybody know where to buy a wiring harness? or if I check out junk yards would a gas or another be interchangeable.

It would have to be a like year truck that is diesel. Gas engine a totally different setup.

That's what I figured, seems like around here diesel's in the junkyard are harder to come by.

It would have to be a like year truck that is diesel. Gas engine a totally different setup.

the relief valve in the rail bad? possible?