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My First Project and GMC has me stumped

whenindoubtuseahammer
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whenindoubtuseahammer New Member

whenindoubtuseahammer

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Good evening. I was lucky enough to get passed down to me a 2007 GMC LBZ that was my great uncle's. While the underside and rockers are more or less gone I feel like with time I can restore it to working order since it only has 110,000 miles and he put nearly every option he could get without getting the new body style since he did not trust DEF. So far I have done everything I can think of but when I put the key into the ignition nothing happens. I put 2 brand new batteries in it. Cleaned the terminals. Check all the fuses and relays and they all pass with my multimeter. I know I'm missing something that I just cant think of. The only odd thing is the OBD2 port works which makes me think its not the mega fuse. Any advice would be greatly appreciated. 

davester Senior Enthusiast

davester

Posted
Posted

are there any codes?

with lots of rust, perhaps disconnect/clean both sides of the connection/examine cable ends (the wires) for corrosion going into the sheath & replace if necessary/reconnect ALL the power AND ground cables between the battery, engine, frame, cab, fuse box and starter

charm.li (website) has a no-start diagnostic procedure you can work through to get it working.

newdude Senior Enthusiast

newdude

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11 hours ago, whenindoubtuseahammer said:

 So far I have done everything I can think of but when I put the key into the ignition nothing happens. I put 2 brand new batteries in it. Cleaned the terminals. Check all the fuses and relays and they all pass with my multimeter. I know I'm missing something that I just cant think of. The only odd thing is the OBD2 port works which makes me think its not the mega fuse. Any advice would be greatly appreciated. 

 

 

So when you put the key in and turn it on, do you have anything at all?  Radio?  Lights?  Or when you key it on its dead?  Or is everything working and it won't crank?    

whenindoubtuseahammer New Member

whenindoubtuseahammer

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16 hours ago, davester said:

are there any codes?

with lots of rust, perhaps disconnect/clean both sides of the connection/examine cable ends (the wires) for corrosion going into the sheath & replace if necessary/reconnect ALL the power AND ground cables between the battery, engine, frame, cab, fuse box and starter

charm.li (website) has a no-start diagnostic procedure you can work through to get it working.

Nothing comes up when I run my scanner on it. It’s hasp power but it’s not wanting to pull any data. I’ll check the ground connections they very well could have some rust I need to clean up to make the connection.

whenindoubtuseahammer New Member

whenindoubtuseahammer

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Posted
9 hours ago, newdude said:

 

 

So when you put the key in and turn it on, do you have anything at all?  Radio?  Lights?  Or when you key it on its dead?  Or is everything working and it won't crank?    

It get absolutely nothing. No chimes, no dash lights, it won’t crank. It’s completely dead outside of the obd2 port which is throwing no codes. I’m wondering outside of a rusty ground somewhere if it could be a connection on one of the fuse blocks? I would not be surprised if water could get under the main panel under the hood on the drivers side. 

davester Senior Enthusiast

davester

Posted
Posted

can you tell if the reader is actually trying to get codes, and the pcm is reporting none, or is your reader just silently failing because it's not communicating with the pcm?

newdude Senior Enthusiast

newdude

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Posted
14 hours ago, whenindoubtuseahammer said:

It get absolutely nothing. No chimes, no dash lights, it won’t crank. It’s completely dead outside of the obd2 port which is throwing no codes. I’m wondering outside of a rusty ground somewhere if it could be a connection on one of the fuse blocks? I would not be surprised if water could get under the main panel under the hood on the drivers side. 

 

 

No key on power = no DTCs.  

 

I'd pull the underhood fuse box as these are known to get nasty with corrosion.  See how things look there.  I'd suspect internal damage as well to it.  

asilverblazer Senior Enthusiast

asilverblazer

Posted
Posted (edited)

Some simple grounds from battery to engine, battery to frame, etc. using jumper cables might yield some clues.

 

Battery condition?

 

Alternator may have internally shorted - pull the power cable off the back if you suspect it.

Edited by asilverblazer
newdude Senior Enthusiast

newdude

Posted
Posted
46 minutes ago, asilverblazer said:

Some simple grounds from battery to engine, battery to frame, etc. using jumper cables might yield some clues.

 

Battery condition?

 

Alternator may have internally shorted - pull the power cable off the back if you suspect it.

 

 

OP put new ones in:

 

Quote

So far I have done everything I can think of but when I put the key into the ignition nothing happens. I put 2 brand new batteries in it. Cleaned the terminals.

 

 

Alternator shorting wouldn't cause a lack of power when keying the ignition to accessory or run.  You can straight up unplug the alternator and the car would still power up and even start.  

asilverblazer Senior Enthusiast

asilverblazer

Posted
Posted
6 hours ago, newdude said:

Alternator shorting wouldn't cause a lack of power when keying the ignition to accessory or run.  You can straight up unplug the alternator and the car would still power up and even start.  

I had an alternator fail that was shorted internally in such a direct fashion in addition to the larger gauge cables that it appeared like a VERY dead battery. Granted I think the car did power up, it definitely wouldn't start.

 

Rodent damage to wiring?

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