2005 Silverado weird electrical problem

finn5033 · August 9, 2015

I am at a loss. I've had my 2005 Silverado 5.3 for only a couple months. Today the wife and I went to breakfast and when we went to leave I turned the key and everything went haywire. The radio reset itself, the check engine light came on faintly and was flickering and of course the truck wouldn't start. There was nothing when I try to start it, no clicking or anything. So of course I first assumed it was the battery or battery connection so I checked that. Connection is good and had battery tested at Napa and it was good. So I started checking other things. The headlights don't work, the power door locks work, the dome lights come on and sometimes look dim and sometimes brighter. Another odd thing is with the ignition off I was able to put it in gear without my foot on the brake. I've done a lot research and find things that seem similar to my problem but the main difference is mine will not start. Any help would be greatly appreciated. Thanks

finn5033 · August 10, 2015

wow 60 views and not one comment? My worry is either the computer fried or the fuse block under the hood.

Badass69 · August 10, 2015

How did you check the cables? Namely the ground? I still would go after a bad ground or power lead and or battery. A lot of Napa's use that handheld cheapie load tester and I find that thing pretty inaccurate. It's going to be one large issue that is common to everything in the truck... hence battery or cables. The truck doesn't even need a pcm for the radio to work so it's a power issue somewhere.

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rjgti · August 10, 2015

what he said ^^^^^^^

finn5033 · August 10, 2015

I spoke with the mechanic at my work that is familiar with these trucks. He said the same thing as you guys. Go back and trace the power and ground cables very closely. He said if it is anything other than a bad cable the issue may be a bad ignition module but to check the cables thoroughly first.

finn5033 · August 10, 2015

Well turns out it was just the battery. I was under the hood inspecting wires and just happened to bump my hand on the negative connection of the battery and it was so hot I couldn't hold my finger on it. Checked a little ways down the negative cable and it wasn't hot. So I decided well before I really start digging deep into this I'm going to try a different battery. Grabbed the battery out of my father in law's truck and put it in mine. Truck started right up. Went and bought a new battery and everything is good except one thing. My truck has the digital dual climate control and now it blows cold a/c from the passenger vents and only hot air from the driver side and rear vents. So that's the next thing I need to figure out.

Badass69 · August 11, 2015

Pull your hvac fuses. One in the drivers door side panel in thr cab and one under the hood. Leave them out for a bit and then reinstall them and start the truck. It will force a relearn on the hvac blend door motors. Just leave the climate controls alone for a few minutes and it will relearn. You might have to do it a couple times but it should take. My old 05 does that constantly when the battery gets disconnected but once it works it's good. Guys will tell you to change a blend door motor but on my 05 in 10 years and 160000 miles I haven't yet or on any other truck I had with it so try that first. I have had 3 with digital climate as gmt800s so I got used to doing this.

If it doesn't work the first time just do it again. I figured the 05 was done for once because it honestly took 5 relearns one time but that was 3 years ago and it's been fine since.

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finn5033 · August 11, 2015

Pull your hvac fuses. One in the drivers door side panel in thr cab and one under the hood. Leave them out for a bit and then reinstall them and start the truck. It will force a relearn on the hvac blend door motors. Just leave the climate controls alone for a few minutes and it will relearn. You might have to do it a couple times but it should take. My old 05 does that constantly when the battery gets disconnected but once it works it's good. Guys will tell you to change a blend door motor but on my 05 in 10 years and 160000 miles I haven't yet or on any other truck I had with it so try that first. I have had 3 with digital climate as gmt800s so I got used to doing this.

If it doesn't work the first time just do it again. I figured the 05 was done for once because it honestly took 5 relearns one time but that was 3 years ago and it's been fine since.

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I went out to try it again and it fixed itself. Must have just needed to cycle through. Thanks