2006 2500HD Lightning Strike

Justjoshiny · January 4, 2020

2006 GMC Sierra 2500HD, 6.0/4l80e push button 4x4 CCLB.

This might be a stretch but maybe someone can help. I have this truck, bought it cheap with some issues. Fixed most of the issues and then it got struck by lightning. I would not have deemed it road worthy yet so I had liability on it. I know, dumb mistake. Anyways, the truck now only has the headlights on and the blower motor running full blast no matter the key position. If you put the key in the ignition, nothing happens. Turn the key forward and the check engine light and transfer case neutral light come on, and thats it. Its pretty fast to drain the battery so whatever it is, is a pretty large draw. I can also control the turn signals, flashers, and power mirrors but those are the only things I've found that work.

What Ive done so far trying to remedy this. I know, its probably easier to write off as a loss and junk or pull the drivetrain, but Im somewhat determined.

Pulled the PCM, checked for any signs of burnt connectors or any corrosion. None. With the PCM out, the check engine light doesnt come on.

Pulled the BCM, no change in how anything works or happens.

Pulled the underhood fuse block, checked all fuses, relays and connections. All appear to be fine. Obviously with the fuse block removed, nothing works. Can get blower motor to stop by pulling its fuse.

Checked everything in the drivers side underdash fuse block, again everything appears fine.

Pulled the little electrical panel below the brake pedal, all connections appear to be fine.

Pulled the connections on the passenger side fuse cover thing and pulling the large brown connector shuts the blower motor off.

Checked most of the grounds that i could find, all seem to be fine.

If theres anything that I couldve missed such as another controller or something, let me know. To my knowledge, with the PCM out, the Interior should all work. It doesnt. With the BCM out, it should still run, but it doesnt.

riverbanks · January 4, 2020

Are you visually checking fuses and relays?or using a test lite?the latter will tell you what feed is shot

davester · January 5, 2020

First, I wouldn't count on a visual check of the circuit indicating it is ok. A lightning strike could easily fry chips internally and may or may not show visible damage.

Second, I would suggest using a more advanced code reader, such as a knock-off techii or autogenuity w gm enhancement, and use it to see if you can read codes from all the computers, and then start working through things one by one to get stuff working (for example, commanding fuel pump to run and verifying that it does, etc...).

And you might wish to get something like an Autel PowerScan PS100 to help you. It works great for testing if a given point has power or ground, and can even tell you if it's pulsed (slow pulses at least, don't know how well this works for injector pulses), and can provide power or ground to test a circuit as well. I find it very useful for doing electrical testing.

But, it wouldn't surprise me if you wind up having to replace most of the computers, and also track down wiring problems as well.

Edited January 5, 2020 by davester

Formulabruce · January 5, 2020

Lightning doesn't "strike" from the sky all the way to the ground. When it gets close to the ground, a ground arc comes up from the ground to meet it.

The truck sits on Rubber.

This would make me think it did NOT get a direct strike, but a partial high voltage in the air nearby type "hit".

When I have heard of this in the past, Things that caused the most issues with odd problems were the Alternator, and starter, where both have lots of coils of wire.

Aside from a BCM, and the BCM ground, under the DS door frame extension ( facing rearward) , I would try a different Alternator and or starter, or both.

I doubt youll be seeing the destruction caused by a direct Lightning strike actually through the truck, like you see in a wet tree, with excellent grounds ( roots).

Good luck, You can beat this...