The Stupid Electronics Questions Thread

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df2x4

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New member here - first cry for help.

The green headlight indicator on my dash is on when the headlights are off. It goes off when I turn them on. EXCEPT - it also goes off if I set the parking brake, which turns on the brake indicator light on the dash. Seems kind of weird to me. But I've never had a GM truck before. Perhaps this is normal?

Completely normal. The green "headlight indicator" is actually a DRL (Daytime Running Light) indicator. These trucks use a module under the dash to illuminate the low beam headlight bulbs at a lower brightness level than normal using pulse width modulation for DRL function. When you turn the headlights on using the switch they go to full brightness, therefore DRLs are off and the dash light turns off. Same deal with the parking brake, engaging that disables DRLs.
 

cpapeter

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Completely normal. The green "headlight indicator" is actually a DRL (Daytime Running Light) indicator. These trucks use a module under the dash to illuminate the low beam headlight bulbs at a lower brightness level than normal using pulse width modulation for DRL function. When you turn the headlights on using the switch they go to full brightness, therefore DRLs are off and the dash light turns off. Same deal with the parking brake, engaging that disables DRLs.
Interesting. And good to know, thank you. Unfortunately, I guess that means I have some other problem. I started my truck up, released the parking brake, and saw the green indicator come on. Walking around to the front of the truck, I have no DRLs lit up. Probably not worth the effort to diagnose and fix. I'm not making a concours d'elegance car here. Just an every day driver.
 

HotWheelsBurban

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Interesting. And good to know, thank you. Unfortunately, I guess that means I have some other problem. I started my truck up, released the parking brake, and saw the green indicator come on. Walking around to the front of the truck, I have no DRLs lit up. Probably not worth the effort to diagnose and fix. I'm not making a concours d'elegance car here. Just an every day driver.
The DRLs are run by a relay under the middle of the dashboard. I replaced it on my previous 99 Burb, when the DRLs quit working on it. On my current Burb, they work for a while, and then will quit working for a while. This last time, they were on for about a month. I'm not interested in crawling under the dash and digging the relay out and replacing it, though I'm sure it's probably bad. As long as it doesn't affect anything else on the truck.... this relay is pretty hard to get to. Was not a fun project before, and I was 10 years younger and more flexible then. Whenever I get to do all the dashboard repair this truck needs, maybe I'll mess with it then.
 

df2x4

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Interesting. And good to know, thank you. Unfortunately, I guess that means I have some other problem. I started my truck up, released the parking brake, and saw the green indicator come on. Walking around to the front of the truck, I have no DRLs lit up. Probably not worth the effort to diagnose and fix. I'm not making a concours d'elegance car here. Just an every day driver.

Do you have factory fog lights? If not you may want to check your fuse box. IIRC the DRLs and fog lights share a fuse, so in trucks without factory fog lights you can just pull that fuse to disable the DRLs. Re-enabling your DRLs might be as simple as replacing a missing fuse.
 

cpapeter

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The DRLs are run by a relay under the middle of the dashboard. I replaced it on my previous 99 Burb, when the DRLs quit working on it. On my current Burb, they work for a while, and then will quit working for a while. This last time, they were on for about a month. I'm not interested in crawling under the dash and digging the relay out and replacing it, though I'm sure it's probably bad. As long as it doesn't affect anything else on the truck.... this relay is pretty hard to get to. Was not a fun project before, and I was 10 years younger and more flexible then. Whenever I get to do all the dashboard repair this truck needs, maybe I'll mess with it then.
I've got the same opinion of working under the dash. Especially for something like DRLs, which aren't critical to the operation of the truck. If I take the front seat out to replace the seat bottom (which is torn - a real shocker, I know!) I might take the opportunity to poke around under there while the access is ever so slightly easier.
 

cpapeter

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Do you have factory fog lights? If not you may want to check your fuse box. IIRC the DRLs and fog lights share a fuse, so in trucks without factory fog lights you can just pull that fuse to disable the DRLs. Re-enabling your DRLs might be as simple as replacing a missing fuse.
I don't think I have fog lights. There's no control for fog lights on the dash. But checking the fuse box makes sense. Thanks for the suggestion of basic things I really should have thought about. Its amazing how quickly we tend to jump to the complex problems when the basics haven't been checked first.

Speaking of which, a quick check of the battery connections wouldn't hurt, either. All of the electronics start there.
 

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Need to tap the hive mind for a weird problem. 98 c1500 ext cab, 5.0l battery is 6 months old and tested good with an electronic tester today. Get in the truck, key to On, dash lights up normally. Headlights work even. Turn the key to start .. all power vanishes. Key to off ... still no headlights, no power in any key position. Come back a couple of days later ... power's back, headlights work ... key to start ... power takes a holiday again.

Ideas?
 

MrPink

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Need to tap the hive mind for a weird problem. 98 c1500 ext cab, 5.0l battery is 6 months old and tested good with an electronic tester today. Get in the truck, key to On, dash lights up normally. Headlights work even. Turn the key to start .. all power vanishes. Key to off ... still no headlights, no power in any key position. Come back a couple of days later ... power's back, headlights work ... key to start ... power takes a holiday again.

Ideas?
Could be the Ign switch
 

TCBRacer77

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New member here - first cry for help.

The green headlight indicator on my dash is on when the headlights are off. It goes off when I turn them on. EXCEPT - it also goes off if I set the parking brake, which turns on the brake indicator light on the dash. Seems kind of weird to me. But I've never had a GM truck before. Perhaps this is normal?
Your lights turn on automatically when you release your emergency brake, therefor turning off the “turn your headlights on” indicator. This green light just tells you that you should turn on your lights. Kind of dumb in my opinion the lights are always on even in the day. My truck is a CA truck maybe it has to do something with state law for daytime running lights.
 
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