SOLVED! 2005 Silverado complete electrical power loss

Drec

Well-Known Member
This is a 1500 work truck with 4.3l with 250k miles and a 5-speed. It only has power steering and a stereo nothing else.

Yesterday while driving down the freeway everything shut off, no lights of any kind or anything else power wise. I called AAA roadside service and got a tow to our old house. So this morning I went out with a multi meter and did a few continuity tests.

The battery tests at 12.8 volts

Then I cleaned the negative cable and when hooking it back up, there was a little sparking on the negative side, then I saw the interior light was on. Tried to start the truck and it started right up, then everything shut off, just like before.

I did a few tests downstream on the cables from the battery for continuity; which passed. But still no electrical power.

BTW, I’m working on our old house in the SEATTLE area and 130 miles from home without any tools. Going back home tomorrow and will start browsing my service manuals. Will be coming back to this side of the mountains and will probably trailer it back home next week.

If anyone has any ideas on what to look for, that would be great. I suppose it could be the PCM or BCM.
 
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TollKeeper

Gold Supporter
So what happens if you turn the key on, engine off. Do you get any lights pertaining to the Security System?
 
OP
Drec

Drec

Well-Known Member
Key on or off, no lights or power of any kind (dash lights, head lights, nothing) but the battery is hot.
 

MRRSM

Lifetime VIP Supporter
This was the closest thing I could find with symptoms like your own. The most immediate cause is surmised in THIS Thread by the OP himself highlighted below concerning a 2004 Silverado and seems like it would not be specfic to the type of Engine in the Vehicle.

The absolute loss of power so suddenly points to a Bad Ignition Switch... or possibly involve a Bad Key Tumbler-Lock Work issue causing the PASS-KEY or other GM PCM Security to invoke to prevent the theft of the Vehicle. Also, having a "Heavy Key Chain" swinging constantly below the Ignition Switch on the Key Rings can also become a factor in damaging the Tumbler over time:


"Yesterday my son drove his 2004 Silverado from Chicago to Green Bay. About half way he stopped and waited for someone. Put the key in Acc position and listened to the radio. After a while turned the key off and the radio played for the usual time and automatically shut off. After it went off, he turned the key back to acc to get it back on. I then arrived to meet him so he attempted to start the truck. The electrical system was DEAD...no lights, windows, anything, except a rather loud clicking from what he thought was behind the dash. It sounded to me like the clicking of a starter solenoid. He said this happened once before about two years ago after he had turned the key to and from the acc position a few times. He had then called for a tow but when he returned the truck started normally and has ran ok for the past 2 years. We waited a while and no change...after about 1/2 hour a friend put jumper cables on and the truck started normally...we traveled the rest of the way to Green Bay making several stops with no problems what so ever. Today we tested the battery and it load tested just fine. It appears that some combination of the acc position on the ignition key somehow locked out the power. Why it started with a jump I do not know. He said last time letting it sit cleared the problem. Any thoughts? No Check engine light, nothing but a complete loss of power...the radio presets were even gone. Is there a master relay in the system that could disable all power?"
 
OP
Drec

Drec

Well-Known Member
I saw that thread, but with a bad ignition switch wouldn’t you still have interior and head lights?
 

TollKeeper

Gold Supporter
I would suggest resetting thru the battery again, key on, engine off, and see if you can pull any codes. But it sounds as if you might not have enough time before it shuts off again.
 
OP
Drec

Drec

Well-Known Member
We tried jumping it and nothing.

In the previous post there was a question that didn’t seem to get answered.

Is there a master relay in the system that could disable all power?
 
OP
Drec

Drec

Well-Known Member
I would suggest resetting thru the battery again, key on, engine off, and see if you can pull any codes. But it sounds as if you might not have enough time before it shuts off again.
I’m not sure what I did to get that to happen. But I did go through all of the steps that I did previously and didn’t get any indication of anything power related. I might have a few minutes to play with it tomorrow. If I get any kind of power I’ll put a scan tool on it; which seems to be one of those tool I pack.
 

MRRSM

Lifetime VIP Supporter
A while back @TJBaker57 did an "Ignition Switch Autopsy" and he found out that the internals can (and occasionally DO) Dead Short under certain conditions. It won't hurt to Swap In another ACDelco OEM Switch. If the Truck Starts... Problem Solved... If not... you will have eliminated the ONE THING that is always the First Thing that must be done to start the ball rolling...By Turning the Key.
 
OP
Drec

Drec

Well-Known Member
The positive battery cable has a secondary cable that feeds the power distribution box (fuse box). About five years ago I replaced the positive cable and there was short pigtail coming out of the primary cable that I spliced into. It appears that this pigtail had a smaller gauge wire that burned up. Anyway there was burnt section of this wire/splice that wasn’t hooked into the positive cable anymore. So I touched this wire to the positive post and the interior lights came on and I was able to start it. In going to look for a heavier OEM cable with a better pigtail.
 
OP
Drec

Drec

Well-Known Member
I looked at the pigtail wire a little closer after stripping back the burnt sheathing and saw that wire burnt between my splice and the positive terminal. There is still a short piece of the wire coming out from the positive terminal that is burnt too.
 
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OP
Drec

Drec

Well-Known Member
Now I’ll have to figure out why it is drawing so much current though that wire and caused it to burn out.
 
OP
Drec

Drec

Well-Known Member
I did a current test through the secondary cable (pigtail) coming out of the positive cable end and into the rest of the burnt out section going to the fuse box. It is pulling .43 amps through the cable. Maybe this is normal. I suppose that the cable failed because of cheap materials. It did last about five years.
 
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OP
Drec

Drec

Well-Known Member
This was an interesting problem. The original positive cable had a secondary 10 gage wire to feed the fuse block; which burned and melted. I ordered a new positive cable from RockAuto, it arrived today and the secondary cable is a lot heavier that 10 gage.
 

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