Crank no start P2146

GregJ77

2004 GMC 2500HD LB7
Mar 18, 2023
27
0
1
Mountain Home Arkansas
Hello all, i am at a loss here. So finslly got my truck up and running new motor, transmission, tcase. I been driving it for about a week. I jumped in it today to run to town and get parts, it started for maybe 3 seconds got a fuel knock and shut down. NOW it cranks but will not start. The fuel gauge also quit working.

I'm getting injector codes P201, 204, 206, 207, and P2146. I found a blown fuse, replaced it i got my fuel gauge back but the truck will still not start. I been researching and some people are saying shafed wires behind the alternator and someone was saying behind the starter? After reading a bit further i found their trucks were lly, mine is a 05 lb7 vin 1. Do these have the same issues? I am at a loss here, i know it had to be a wiring issue, everyrhing is new and I've had no issues, no codes or anything. Has ANYONE had this issue before? I'll upload some pics of the codes. I know the B codes are probably because i unplugged some stuff looking around.
 

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TheBac

Why do I keep doing this?
Staff member
Apr 19, 2008
15,269
1,561
113
Mid Michigan
Sure your bale connectors are tight and locked down? Id also be checking the wiring around the FICM for chaffing and wear.
 

GregJ77

2004 GMC 2500HD LB7
Mar 18, 2023
27
0
1
Mountain Home Arkansas
Bale wires are good, i unplugged them and plugg3d them in about 20 times. Tomorrow i am gonna check behind the alt for shaffing. Have you heard of the erea behind the starter being an issue? I'm thinking about pulling the starter and checking there also. This shit just has me stumped man.
 

BrandonLLY

Member
Apr 23, 2014
116
8
18
05 with an LB7? How is that? I thought they stopped using in early 04 .


Sent from my iPhone using Tapatalk
 
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TheBac

Why do I keep doing this?
Staff member
Apr 19, 2008
15,269
1,561
113
Mid Michigan
Bale wires are good, i unplugged them and plugg3d them in about 20 times. Tomorrow i am gonna check behind the alt for shaffing. Have you heard of the erea behind the starter being an issue? I'm thinking about pulling the starter and checking there also. This shit just has me stumped man.
If youve had the connectors apart that many times, you should make sure the pins are all still seated properly. They can back out and not make good connection.
The only wires around the starter (or around the bottom of the engine for that matter) that I would be concerned about would be the multiple grounds found there.
 
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GregJ77

2004 GMC 2500HD LB7
Mar 18, 2023
27
0
1
Mountain Home Arkansas
Im gonna say my ficm is bad. I have checked every ground, I've checked all the pins, everything ohms tested to spec, it's a no crank and no start so im pretty sure the ficm fried. Only thing is why, everything is jew and good. This truck has been an on going build for 6 months and it's been a disaster. I am a cummins guy and im so cloae to cummins swapping this shit show. Lmao
 

GregJ77

2004 GMC 2500HD LB7
Mar 18, 2023
27
0
1
Mountain Home Arkansas
Man i am at a loss here. All my wires are perfect, still in the plastic cover being protected, every thing ohm test good. It must be the ficm is all i can think. Everyone elses rigs run with the P2146, P201, P204, P206 and P207 codes but mine dont. It blew the fuse and even the fuel gauge quit working replaced fuse, gauge works now cleared codes but it's still a no start. 😳😳😳
 

GregJ77

2004 GMC 2500HD LB7
Mar 18, 2023
27
0
1
Mountain Home Arkansas
It was one of the 25 amp injector fuse. The fuel gauge wasnt working when i put the new fuse it it started working, i cleared the codes but still a no start.
 

GregJ77

2004 GMC 2500HD LB7
Mar 18, 2023
27
0
1
Mountain Home Arkansas
I found the problem. I have a fried FICM. anyone on here have one for sale?
 

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GregJ77

2004 GMC 2500HD LB7
Mar 18, 2023
27
0
1
Mountain Home Arkansas
What do you guy's think could have xaused this? I know mostley in LB7'S FICM failure is rare. I've searched low and high for shaffed or bare wires. I did have a small diesel leak and it started hard starting could air and teying to crank dry cause this? I also found some rust in an injector tip when i pulled the lines off. This engine came out of a truck that sit for almost a year. It only has 117k miles and the ol man i bought it from got T boned. His son talked him into buying the truck back, then the guy got on drugs went to jail so he never planned on doing anything with the truck after that, so i bought tue motor for 2k.

I got all new lines now, but this truck ran flawless, the engine oil has about 300 miles and STILL looks brand new, i mean it's a GOOD motor. Today i will be looking at all the wires on the driver side to see if i find anything. While I'm in here im replacing all the return lines with pre molded ones. I put new fuel lines on it before i put it in the truck. But i think one of them might be kinking. It was just regular hose i used off my roll of fuel line i had. (And guys i am sorry, i know my Grammer sucks) lol
 

Bdsankey

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Vendor/Sponsor
Feb 1, 2018
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Kinda looks like just plain shitty luck. Anything can fail. Moisture is usually the cause of most failures I've seen but I'm not an electrical engineer to be much help beyond that.
 

2004LB7

Well-known member
Dec 15, 2010
6,274
1,683
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Norcal
It's hard to say. I believe that those capacitors are part of the internal regulator for the ficm and not supplying any power to outside the ficm. They are only 50 volt capacitors while the injectors run up to 96 volts
 

2004LB7

Well-known member
Dec 15, 2010
6,274
1,683
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Norcal
There's a bunch of them on ebay for under $500



 

1FastBrick

Well-known member
Dec 1, 2016
2,157
789
113
Junkyard
I wonder if the cap just started leaking at the base and the rest was history???

With these things being 20 years old, Might not be a bad idea to send the replacement in and have it serviced for piece of mind.
 
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