LB7: Sputters an dies..Cranks back up...U1000 DTC???

[MMLMM]

LB7, EFI tuned, fass150.. truck sputters and dies while driving. Now it cranks over starts and dies again.

Lift pump is pumping
stock tune, modded tune, and hot tune = no change
DTC U1000 often when happens

The gauges sometimes dont work, but that has been like that for a long time....Usually they take a few minutes to "fire up". The stalling condition wasnt there until yesterday, the gauge issue has been there for around a year.

Truck seems to be getting fuel.
ECM should be good, and hasnt been removed in like a year.

 

[Smokin LB7]

Something weird happening with the VATS?

Bad FICM...dont know if that would set more codes or not though

 

[bluessmax]

had this problem and same code of a truck awhile back, the fix (after chasing our tails) was simply...a bad ground/connection. It is electrical sounds like and the u1000 is a communication problem iirc.

 

[Chevy1925]

Security light stayin on?

 

[MMLMM]

VATS disabled, no sec light. Im thinking ground, just have to find it.

Truck wont start at all now.

Lots of codes all of a sudden...

 

[bluessmax]

more than likely it is a ground, i just searched it a little and seen where many others have reported with that code it was connection related..now the fun starts trackin her down

 

[Akdiesel]

My truck runs, drives and starts fine. My u1000 is because I had RSE and now have an aftermarket head unit fwiw.

 

[schulte]

Check the MAF. Can cause some of that cranks then dies right away, sputters at idle then dies, etc.

 

[Chevy1925]

VATS disabled, no sec light. Im thinking ground, just have to find it.

Truck wont start at all now.

Lots of codes all of a sudden...

yeah im puttin my money on a ground

 

[RENODMAX]

yeah im puttin my money on a ground

X2. Where is the truck located? Does it see salt etc. and has it been in a wreck?

 

[schulte]

Do you have stock batteries or are they aftermarket "dual terminal" style?

I had an issue once on mine where my aftermarket batteries (with both top and side terms) would short against the hood on the pass side batt, making the truck stumble for a second or sometimes die if the bump was severe enough.

 

[Chevmeister]

I had the same issue on my lb7 and it blew a fuse for the ficm. A terminal in the bale conector was loose and i guess the resistance was enought to wack it out, eventually it blew a fuse. My truck only restarted once before it died completely. I got all kinds of codes: comm error, cranck pos sensor, miss on clyinder*, i dont remember them all, but it sucked. It was raining, and my wife was out in it with all 3 kids.
I got a few *1000 codes today because I didnt plug my bale connector in completely on my lly. No crank no start.
I would ASSuME you have checked the bale connector, but if not its worth a few seconds of time.

 

[MMLMM]

X2. Where is the truck located? Does it see salt etc. and has it been in a wreck?

truck is in New Mexico, Never wrecked, Motor has been out and rebuilt long ago, but has been running fine for quite some time now.

Do you have stock batteries or are they aftermarket "dual terminal" style?

I had an issue once on mine where my aftermarket batteries (with both top and side terms) would short against the hood on the pass side batt, making the truck stumble for a second or sometimes die if the bump was severe enough.

Dual interstate batteries. Checked all there connections, load tested, and looked for corrosion in cables. Everything seems good there.

I had the same issue on my lb7 and it blew a fuse for the ficm. A terminal in the bale conector was loose and i guess the resistance was enought to wack it out, eventually it blew a fuse. My truck only restarted once before it died completely. I got all kinds of codes: comm error, cranck pos sensor, miss on clyinder*, i dont remember them all, but it sucked. It was raining, and my wife was out in it with all 3 kids.
I got a few *1000 codes today because I didnt plug my bale connector in completely on my lly. No crank no start.
I would ASSuME you have checked the bale connector, but if not its worth a few seconds of time.

Checked the bale connectors.

Truck is all apart right now cleaning all the connections on every plugs (ecm/tcm/bales/senders/etc.), double checking everything. Looking at all the ground straps, jumping them and trying.

New codes are C0550, P1550, C0201, U1800 and still seeing the U1000 also.

Well see how checking all the connections and cleaning them up goes, if it dosent fix it, off to the dealer tomorrow on a trailer.

Thanks guys!

 

[RENODMAX]

Id go through the grounds. That type of code pops up a lot when a truck has been wrecked hard (broken grounds) or when there have been any sort of tampering with grounds (pulling motor out). Check make sure they are all in place and also check upstream from where they terminate to see if they are pinched, worn etc.

 

[MMLMM]

Thanks.

Well everything was checked, every single connector lol. Unplugged, cleaned, re plugged in, All the grounds that could be found were un bolted checked for continuity and re installed, and the rest that cant be unbolted were checked for continuity as close as possible, everything was inspected.

At a loss.

Owner is taking it to dealer and let them look.

Upside is all the connectors are all cleaned and pretty

Ill report what the dealer finds.

 

[GMC_2002_Dmax]

Reluctor wheel on the crank ??

 

[bluessmax]

got me stumped then, ready to know the fix

 

[RPM Motorsports]

Two orange wires (paired together) on the C2 have a bad connection @ the fuse box? I just finished an LB7/LBZ swap. Before moving the two wires to match LB7 fuse box to LBZ connector, it would crank die crank die. after about 7-10 tries it would finally start and run. Once the two wires were pinned together it would fire up the first time. one goes to the tcm.

 

[MMLMM]

Some fuses had loose connections in the fuse box.

Take a look at your guy's trucks just in case.

Trucks running good now.

 

[bluessmax]

Glad to see ya got it worked out:thumb: