CP3 electrical issue, help needed please

NastyNate

NastyNate

Really fast learner
Jan 15, 2007
188
0
0
Colusa, Ca.
Wondering if anybody can help with a CP3 electrical issue. Coming off the engine harness there is a three pin connector (harness side), to the CP3. One pin should have 12v.(it does), the center pin should have 3v. (it does not), and the third pin should have 0v. (it does). The center pin that "Should" have the 3v. Signal has been traced back through the ECM. The ECM is not showing the 3v. Signal. The ECM and FICM were swapped out to see if the issue was either one, still no 3v! What else tells the ECM that it needs the signal? The truck has a dual CP3 kit, but it has been disconnected, and removed from the loop. Rail psi. Is all over the place very fast from 5K-26K psi. Any ideas?
 
S

stacks04

Member
Nov 16, 2007
792
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Terryville,Ct
Fuel Controls - Fuel Pump, Temperature, and Pressure Controls

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ripmf666

ripmf666

Active member
Sep 20, 2006
15,123
14
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47
Wentzville Mo
your stuck with that size even when I post it in the Gm spec area it stays that size. Its the way we have to copy it from Gm Service info that makes it that way.
 
TrentNell

TrentNell

Finally underway !!!!!
Jul 7, 2008
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slc tuah
I know this is kinda an obvious thing to check but have you checked the ground for the cp3 controller ? controller itself been swapped ?
 
RPM Motorsports

RPM Motorsports

smokinum
May 13, 2008
3,271
10
38
Central Valley Ca.
rgullett83 said:
Is this the truck Russ has been workin on?
Click to expand...

It's Nates truck, and we are both trying to figure this thing out. Neither one of us knows much about the electrical side of these trucks:rolleyes:, and we are stumped.

Trent- the dual controller was taken out of the picture, and the belt is off the 2nd CP3. No signal straight from the ECM! It does run better with the 2nd CP3 controller plugged in, and belt on. but it still runs rough, with an intermitent burp of white smoke.
 
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TrentNell

TrentNell

Finally underway !!!!!
Jul 7, 2008
7,543
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slc tuah
rail pressure should be controlled by 2 things , the rail pressure sensor , and the regulator the ECM sends signals to the reg based off of what the sensor see's. I would unplug the reg and make sure it pegs rail, if it doesn't or still fluctuates then its the reg , also log regulator current to see if its the ecm that has the reg hunting possibly from not getting accurate rail pressure signal .
 
Brayden

Brayden

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Jan 16, 2008
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Are you talking about the rail sensor? There should never be 3V on a circuit unless that is the signal from a 0-5V sensor.

Say that the signal from the rail pressure sensor is at 3V, that is roughly 18000 psi. It shouldn't idle at that.

Do you have current at the regulator? It should click on and off as you unplug it and reconnect with the key on.

Give me a call tomorrow if you need more help.

Brayden
 
RPM Motorsports

RPM Motorsports

smokinum
May 13, 2008
3,271
10
38
Central Valley Ca.
Brayden said:
Are you talking about the rail sensor? There should never be 3V on a circuit unless that is the signal from a 0-5V sensor.
Click to expand...

Nope talking about the three pin connector off of the main engine harness that goes to the valley CP3! With the key on, my LBZ and two other trucks that were tested had 12v., 3v., 0v. Nates truck is not getting the 3v. (center pin on harness) to the CP3!
 
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