Truck won't run without rail pressure gauge

chris lang

chris lang

New member
So, on top of my problem with hp tuners, my truck won't run withou the rail pressure gauge plugged in. I tried unplugging it and plugging to plug the cummins harness straight to the sensor, when I turn the key on it cycles all the relays and fca. Plug just just the harness into the rp sensor harness and it goes back to normal, will even start but idles rough.

I just had dodge reflash the ecm's to try to fix the problem with hp tuners, and the rp gauge was hooked up when they flashed it.

Does anyone have an idea on this? I want to get rid of my gauges and just use and edge insight...plus I don't want my truck to shut down if the rp gauge ****s the bed.

Thanks,
Chris
 
The only that 0ops in my head is a ground issue, it's using the gauge as a ground for the ecm.

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Unfortunately, that would make sense.
I don't have another truck to try it on, but if you disconnect the rp sensor it shouldn't cause all of the relays and fca to start cycling should it?
I tried uploading a video of it on here but it wouldn't work.
 
chevota84 said:
The only that 0ops in my head is a ground issue, it's using the gauge as a ground for the ecm.

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Click to expand...


Yep, you were right. I disconnected the wires from the gauge one at a time and sure as chit it's the ground from the sensor and ground for the gauge that is making it work. So, my engine has been grounding through my rp gauge all this time. Does anyone know what pin on the ecm is the sensor ground by chance?
 
Well, just took the ecm and backing plate off. Cleaned everything. Put it back together. I had between 500 and 1k ohms from the ground on the rp connector to the bolt on the backing plate that grounds from the backing plate to the engine block.
I had good continuity from rp connector ground to pin a53

Still does the same thing
 
Ok, what I called grounds earlier I think are 5v supply.
On the c2 connector I have continuity to ground at 12, 46 and 47.
Powers on 20, 30, and 40.
 
Ok well, this is embarrassing. I mistook the ground for the grid heater as the power.

Anyhow...you should have ground at pins 21, 49, and 50 on the c2 connector. Once I I got a wiring diagram I realized what I did as soon as I looked at it.
 
At least you got it straightened out, that kind of stuff will give you gray hair.

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Yea, I went through my weekly beer allowance in 2 days.
Still have the hp tuners problem but at least Daisy is ok
 
I keep getting a checksums validation failed message. It won't read the ecm, I've taken it to dodge and had the reflash all the ecms.
I've emailed hp tuners and all they said is the know about it and are working on it...so I'm sitting on $800 worth of nothing I can use or return.
 
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