[Dproffitt101]

I have a 2005 duramax lly throwing code p0090. Found signs of mice chewing on wires also. Checked continuity between c1 pins on ecm and fpr everything tested good but no voltage to fpr nor will the truck start. I'm leaning on a bad ecm but was looking for a second opinion

 

[Ron Nielson]

What pins did your check on the C-1 connector? The pin that would have power to the FPR would be 42 on the C2 connector. Sure, it could be the ECM, but more likely the FICM, as they are quite problematic and at the age of the FICM trucks, FICM is just getting worn out.

42

PU/WH

2530

Fuel Pressure Regulator Supply Voltage

 

[Dproffitt101]

I checked 37 and 40 on c1. They both showed good continuity to the plug at the fpr

 

[Dproffitt101]

This is the pinout I was using. According to my pinout c2 pin 42 is yellow and reads frp sensor signal

 

[Ron Nielson]

Glad that you fixed my mistakes! And I like it when someone has wiring diagrams!

 

[Dproffitt101]

Out of curiosity if there was a problem with the ficm would that cause there to be no voltage coming to the fpr

 

[Dirtymax1515]

Check all power and grounds to the ecm . Verify they are there, then move to ficm. You can back probe it or unclip the connector and check it from the front side . Doing it the last way I mentioned will set CEL so have a scan tool handy to reset codes.

 

[Dproffitt101]

Finally got a computer hooked up to and it shows no communication to the ficm. Checked pins and I have no voltage going to ficm. Checked edu fuse and it's good. Continuity from edu fuse to ficm is good also. No voltage going to the edu fuse while key is on. Went to the edu relay. Have good continuity from fuse to relay. Changed out relay and still no voltage to fuse. Pretty sure whatever wire feeds the relay from the run to start on ignition may be bad but can't find a broken wire. Do have 12 volts going to relay but nothing on the post that should have voltage when the key is turned. Thinking on just running a jumper and see if it solves everything

 

[Dirtymax1515]

Finally got a computer hooked up to and it shows no communication to the ficm. Checked pins and I have no voltage going to ficm. Checked edu fuse and it's good. Continuity from edu fuse to ficm is good also. No voltage going to the edu fuse while key is on. Went to the edu relay. Have good continuity from fuse to relay. Changed out relay and still no voltage to fuse. Pretty sure whatever wire feeds the relay from the run to start on ignition may be bad but can't find a broken wire. Do have 12 volts going to relay but nothing on the post that should have voltage when the key is turned. Thinking on just running a jumper and see if it solves everything

Just double checking , we're you meaning to type ecu?

 

[Dirtymax1515]

Nevermind, I re read your whole response. Do you have access to a poweprobe ?

 

[Ron Nielson]

//EDIT With key turned to start position //
Power comes into the EDU relay, then to the EDU fuse. If you have power at the relay, and the ground on pin 85 is good, power passes to the EDU fuse. If no power at EDU fuse, the wire/circuit is broken. When the power goes to the EDU fuse, it also goes to the ECMRPCV fuse. Check here to see if you have power.

 

[Dproffitt101]

Have power to edu relay but no power to edu fuse or ecmrpv fuse. And good ground on pin 85

 

[Ron Nielson]

Check pin 87 of the EDu relay with the key turned to start. If not voltage there, my GUESS is that you have a bad fusebox or bad connection between the relay and the fusebox.

 

[Ottowood]

Pull the cover from the bottom of the fuse block and check all the wiring.. Rodents love that area for nesting.

 

[Dproffitt101]

Check pin 87 of the EDu relay with the key turned to start. If not voltage there, my GUESS is that you have a bad fusebox or bad connection between the relay and the fusebox.

I do have voltage there with key on

 

[Dproffitt101]

Pull the cover from the bottom of the fuse block and check all the wiring.. Rodents love that area for nesting.

That's what I'm fighting now. Just having problems finding bad wire

 

[Dproffitt101]

Does anyone have the pinout diagram for the under the hood fuse block. If I know which pins are supposed to be hot maybe I can find out which wire may be broke

 

[michael86385]

Any luck with this

 

[dproffitt101_5073]

Any luck with this

Replaced the whole fuse block now I have power to the fpr and ficm but when I tried to start it the starter locked up. Lol my luck. Got a starter to put on it but been working alot of hours and haven't had the time to install it