LB7: SOS....Need HELP. Truck wont start

[duramax hd]

Ok, here is the deal. Been going crazy over this for the past week. Ask my buddies, Ive been driving them crazy asking them questions all damn week and I'm throwing in the towel and asking for help.

As you all know, I bought a built motor two months ago as I windowed my block. Long story short, I put it all back together last week and finally got it to start on sunday. On first attempt running my old (LB7 reg) tuning it would not start. It threw a few 3 P0380 codes for the glow plug circuit A and 3 P0540's for air intake heater circuit. I then realized I have dual LBZ pumps now so Tony reflashed the ECM with rescaled LBZ reg tables. After I got the ECM in, it ran for 20-30 minutes and died. In the 20 minutes of running, it had max rail pressure at idle which we attributed it to needed to scale back the tables even more and we ruled out a stuck regulater as rail pressure would come down if you increased RPM's. the reason my truck died is now why Im asking for help as I havent been able to get it restarted since nad Ive tried every day.

The P0380 code I have a feeling that it was causing a major draw on the charging system and that the glow plug relay is shot and that caused my truck to die innitially. Thats what I gathered with my searching. So I unhooked the glow plug module entirely to rule that out. Also, in the process blew the #1 40 amp fuse in the main fuse box after trying to jump start the truck after killing the battery. Not sure why that happened? It hasnt blown since, but now the only code I get is a U1096 (lost communication with instrument panel) code and still no start. I do have a very odd buzzing noise coming from somewhere and I cant seem to track it down. The only thing I can say is when I pull the big #1 IGN fuse in the main fuse box it goes away. Can anyone say for sure if a CP3 can buzz? When I pull hte fuse, it sounds like its coming from one of the CP3's and its even transmitting a vibration troughout many parts of the motor that I can feel? WTF

Video of buzzing noise. Sorry for the swearing. This was sent to my buddy: http://www.youtube.com/watch?v=q9O8205dvSM&feature=g-crec

Ive checked and double checked all the grounds on the motor with no change. I do not know where to go from here. I have even bought a brand new battery today as I read that some have attributed a "buzzing noise" to bad plates in a battery.

Im ready for a some gasoline and a match.

I have my buddy coming down tomorrow with his LB7 and we are going to double check that everything is hooked up correctly to rule out any chance of that causing this. The truck ran for 20 minutes and its killing me that I have all these isses after the fact.

Anyone?
Can anyone help?

 

[delong_1]

I believe the cp3 can buzz, mine does this with the key on engine off.

Have you watched rail and such with Efi live or tech 2?

 

[duramax hd]

I believe the cp3 can buzz, mine does this with the key on engine off.

Have you watched rail and such with Efi live or tech 2?

I dont have EFILIVE or a tech 2 to watch rail but I do have a rail pressure gauge that has helped me in starting the truck. it used to go up to 7500psi on startup after we rescaled the tables. after that it would climb up slowly to max rail pressure. Now I dont get any rail pressure when I crank the truck over. guessing that has to do with the U1096 code?

how loud does yours buzz with the key on> If you watch the video, its pretty audible...I also never heard this before.

 

[Evan@InglewoodTrans]

The truck should of started before you rescaled the FPR's. CP3's can buzz ive heard it before and codes or not your truck should build rail pressure while cranking.

 

[duramax hd]

when I first tried starting it, rail pressure was wicked high. Something like 18-19000psi on cranking. After tony flashed the ECM, it started no problem. What else could cause a cp3 to not build rail pressure? It builds none now when im cranking it over. Regulater wide open? could it be a bad CP3 controller?

It used to smoke white pretty good while cranking it over but since that code, Im not getting any rail pressure nor smoke.

 

[adeso]

Something going on with the reg? does it do it when you unplug the FPR? I'm just guessing here. Do you have the VATS disabled?

 

[adeso]

with the FPR unplugged it will command max rail
edit, not command but rather the fpr will be in the setting to give you max rail

 

[770JOHNNYW]

I bet your fprv is stuck open.

 

[adeso]

I would check for fuel leaks, check for fuel in the oil, check the VATS, then try starting it with a FPR unplugged to rule out something being shorted out

 

[duramax hd]

with the FPR unplugged it will command max rail
edit, not command but rather the fpr will be in the setting to give you max rail

SO if I unplug the sensor, it will go to max rail pressure?

I bet your fprv is stuck open.

do I pull the pump up tops plug and see if that one build rail?

 

[Evan@InglewoodTrans]

If the FPR is unplugged it will max out.

 

[770JOHNNYW]

I think.I would plug the fprv anyway. Just drill and tap the banjo bolt and put a set screw inside the bolt

 

[trevrosborough]

x2 start with simple stuff like leaks and make sure you have fuel to the pumps or atleast to the filter head its not the vats cause they just dont fire the injectors you have a fuel issue some where i would say a pinched line mabe?

 

[Evan@InglewoodTrans]

If it was my truck I would find a way to moniter rail pressure to start. Check all fuel lines to make sure they are tight.Eliminate the second cp3 snd wiring.Then check all the wiring again.

 

[duramax hd]

Update on this. I can chalk some of the issues I was having to my own stupidity. I still have some unresolved big issues though. The no rail pressure was caused by me diagnosing the electrical problem and unhooking the power to my airdog....well forgetting they arent flow through, and cranking it over a bunch of times will cause that.

So now the fun part. Truck starts and runs perfect...Except the alternator isn't turning on or charging. I ahve several communication codes and through thread searching and my buddies countless hours of research, I can conclude the BCM codes I have are 100% related to the alternator recieving a signal to charge. I just cant find what happened or is causing this. Codes are:

P0622 Generator 1 F-1 Terminal Circuit
C0265 Valve Relay coil circuit open
B0077 Center Rear Seat belt Sensor circuit
U1000 Class 2 Data Link
U1096 Lost Comm with driver information and display
U1064 Lost Comm with Body controller

I know the alternator circuit flows through the BCM, followed by the ECM to send a signal to turn it on. With every single thing working from cluster to headlights electrical, what the hell is causign this. I have to run the truck off a battery charger while I troubleshoot this but I cant find any wiring or ground issue that is wrong. I spent the day looking at another LB7 and double checking every ground on the engine and even re-doing all of them. Nothing is hooked up incorrectly. Did I fry something? If I can get my hands on a tech 2, is there anything I can diagnose? Need help big time here.

 

[juddski88]

you said it blew a 40amp fuse right? are all the others ok?

 

[Chevy1925]

i would be searching for ground and double check ALL fuses Kris.

start the truck and unplug the alternator plug, test each lead and see if any lead is showing 12v's.

 

[MACKIN]

When you blew he fuse during the jump start how do you know if the alternator isn't fried? Why not pull it and have it tested?

 

[duramax hd]

you said it blew a 40amp fuse right? are all the others ok?

Yea I innitially blew a 40 amp fuse when my glow plug module was f-ed up. I have that 100% disconnected now to rule that whole thing out of the equation. Is there something referenced in the BCM that needs to be connected on the glow plug module side/Air intake heater that would cause a loss of Comm? I dont think there is? But that fuse has obviosly been replaced now

i would be searching for ground and double check ALL fuses Kris.

start the truck and unplug the alternator plug, test each lead and see if any lead is showing 12v's.

I double and triple checked both. HAving another set of eyes on this yesterday really confirmed that I'm not overlooking the simple stuff like that. Every fuse that has power on one side, has power on the other. Confirmed multiple times by two people. And as far as the grounds go, every engine ground has been gone through. Some of the codes referenced come up with other chasis grounds that were not touched. Should I be going through the whole truck? Also, we performed this test by unpluging the alt and testing for 12v....there is nothing

 

[duramax hd]

When you blew he fuse during the jump start how do you know if the alternator isn't fried? Why not pull it and have it tested?

Mack,

I actually did think the alternator was fried and I put a brand new one on last night even after I had mine bench tested and verified good. So its not the alternator. Its something not telling the alternator to turn on...