Help: Lb7 no start

aaronlev03

New member
Dec 16, 2008
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Hey guys I'm looking for a little help. I've got an LB7 I just pulled the motor out of to do a head gasket and now its back in and for some reason the starter isn't getting the signal to engage. When I first had the motor back together it fired fine and I started it about 3 times found I had a fuel leak looked into that and now the starter isn't gettin signal. This is what I've tried so far the starter will work fine if hot wired and if I take the top of the relay off and bypass. I tried another starter, I replaced the relay, checked every fuse having anything to do with the ignition, I replaced the the ignition switch, tried grounding the TCM having heard that that can cause this, I checked the voltage on the batteries jumped the batteries and tried different batteries. Checking the relay connection while trying to start the only prong of the 4 that is hot is the power source the one going to the starter is cold the one going to the ecm is cold and the one going to the tranny is cold. I have heard that a bad neutral safety switch can cause this and am wondering if anyone knows how to test that? Any help or suggestions would be much appreciated.
 

AubleAK

New member
Aug 5, 2011
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Glennallen, AK
is the gear indicator showing that your in park or neutral? Fill out your signature, then the guys will know what all is done to your truck, and may help trouble shoot your problem.
 

AubleAK

New member
Aug 5, 2011
781
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Glennallen, AK
has it thrown any codes? from my experience if the NSBU goes out it will throw a code. but if its showing which gear your in it seems like it would be fine. atleast to start.
 

ctrump90

ctrump90
Jan 11, 2012
471
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Clare, IL
Does the truck have remote start or aftermarket radio?? try pulling radio fuse ive seen my buddies truck do some weird stuff because his radio fights with the alarm...
 

aaronlev03

New member
Dec 16, 2008
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The check engine light isnt on but i'm bringing EFI live to the shop tonight to scan it to see if there are any codes getting throne.
 

aaronlev03

New member
Dec 16, 2008
11
0
0
new development with the truck. I scanned it with EFI live and it is throwing a bunch of codes p0090, p0380, p0381, p0540, u1800, p0727, u1152, u1026, u1041. I cleared them and p0380 and p0381 came back.
 

JoshH

Daggum farm truck
Staff member
Vendor/Sponsor
Feb 14, 2007
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Texas!!!
I merged your threads to get everything in one place.

I think there are a couple of fuses that can cause no power to get to the starter solenoid. I'll have to do some checking though. What year is your truck?
 

JoshH

Daggum farm truck
Staff member
Vendor/Sponsor
Feb 14, 2007
13,712
773
113
Texas!!!
In the underhood fuse block check the IGN A fuse (40A), CRNK fuse (10A), and the IGN E fuse (10A). Those can all cause your problem.