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Discussion Starter · #21 ·
Latest update: Well i tryed changing the entire dash harness and still nothing. Next thing im gonna do is try to swap the bcm. If that doesnt fix it. Off to the dealership she goes
 

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Body relay block located just above the data link connector melted relay connection?. Instrument panel fuse block melted/corrosion? multifunction light switch on the column?
 

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Discussion Starter · #23 ·
Body relay block located just above the data link connector melted relay connection?. Instrument panel fuse block melted/corrosion? multifunction light switch on the column?
I checked the body relay block and instrument panel fuses, actually the dash harness i swapped in had another instrument panel fuse block attached to it so i tryed a whole other set of fuses and it didnt seem to fix anything, ive also swapped out the multifuntion switch as well and nothing changed, if its not the bcm then theyre has to be a ground i dont know about or something messed up
 

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auto headlight sensor detects that its daytime then in that case nothing will come on at all.
Focus on fixing this. It seems to be a common denominator. If you can get hold of the factory service manual electrical volume it will be easier. Those aftermarket books leave out a lot of the good stuff.
You always find the problem in the last place you look. The trick is to look there first.
 

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Discussion Starter · #25 ·
Focus on fixing this. It seems to be a common denominator. If you can get hold of the factory service manual electrical volume it will be easier. Those aftermarket books leave out a lot of the good stuff.
You always find the problem in the last place you look. The trick is to look there first.
I am no electrician man, those manuals and diagrams are spanish to me (i dont speak spanish) but it doesnt come down to the sensor its the headlights themselves, whether i turn them on with the switch or they turn on by themselves via the sensor everything in the cab starts working again. The sensor is working fine and turning the headlights on and off when its bright or dark, problem when it shuts the headlights off during the day it takes everything else with it or if i shut them off manually via the switch
 

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do your daytime running lights work? Could the previous owner/driver have messed with it? heres a clue: "I’ve got a 2003 Chevy s10 ZR2 and I cut the center yellow wire on the relay behind the brake pedal (there were two) and my DRL’s are still coming on, I’ve been trying to figure this out since I’ve had the truck and nothing is turning them off besides pushing the dome override button 4 times" 2003 ZR2 disable Daytime running lights - DRL
Watch this video the first part is about disabling daytime running lights.Toward the end he shows no dash lights unless the headlight switch is in Park lights position.
 

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Discussion Starter · #27 ·
do your daytime running lights work? Could the previous owner/driver have messed with it? heres a clue: "I’ve got a 2003 Chevy s10 ZR2 and I cut the center yellow wire on the relay behind the brake pedal (there were two) and my DRL’s are still coming on, I’ve been trying to figure this out since I’ve had the truck and nothing is turning them off besides pushing the dome override button 4 times" 2003 ZR2 disable Daytime running lights - DRL
Watch this video the first part is about disabling daytime running lights.Toward the end he shows no dash lights unless the headlight switch is in Park lights position.
i went and double checked the headlight sensor and wiring and even changed the sensor itself out to no luck, also tried a new body control module and nothing. I did realize that I'm not getting power to the obd2 port on the truck when the headlights are off as well, so I can eliminate basically every component in side the cab, its got to be a problem with the wiring coming into the cab from the firewall. once the dash comes out this Saturday ill start attempting to ring out wires and see what I can come up with
 

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IIRC, the power for the OBD port is on the (15A) cigarette lighter circuit (per my '03 sonoma 4x4) - have you checked that fuse? This may or may not be relevant or related to your issue, but just something else to check out.
 

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Discussion Starter · #29 ·
IIRC, the power for the OBD port is on the (15A) cigarette lighter circuit (per my '03 sonoma 4x4) - have you checked that fuse? This may or may not be relevant or related to your issue, but just something else to check out.
yes the fuse is fine, whenever I turn the headlight switch to "on" power comes back and I can read codes, it only doesn't work along with everything else I mentioned before when the headlight switch is in the off position
 

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That circuit is an orange wire which means it's B+ voltage. Not ignition. There aren't a lot of orange wires on the truck. Only the things that have to work even if the key is off. Like interior, exterior and brake lights. Any where you see one test it for voltage with a test light. Might help narrow down the source of the problem. If you have access to any wiring diagrams look over the power distribution diagrams.
One of those orange wires goes from the parking lamp fuse under the hood to the parking lamp relay in the body relay block, behind the headlight switch. Then to the headlamp fuse. Check both the Parking lamp fuse and relay. That Parking lamp relay is also connected to the headlight grounding relay. Seems to be a location where the headlight and other lighting interact. Which would hint it might be involved. Test both those relays.
 

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Discussion Starter · #31 ·
That circuit is an orange wire which means it's B+ voltage. Not ignition. There aren't a lot of orange wires on the truck. Only the things that have to work even if the key is off. Like interior, exterior and brake lights. Any where you see one test it for voltage with a test light. Might help narrow down the source of the problem. If you have access to any wiring diagrams look over the power distribution diagrams.
One of those orange wires goes from the parking lamp fuse under the hood to the parking lamp relay in the body relay block, behind the headlight switch. Then to the headlamp fuse. Check both the Parking lamp fuse and relay. That Parking lamp relay is also connected to the headlight grounding relay. Seems to be a location where the headlight and other lighting interact. Which would hint it might be involved. Test both those relays.
Awesome, will definitely look into these things more closely next
 

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Might want to pull each and every fuse including the big ones in the underhood box and test them with an ohm meter. Sometines they can look OK and be fried.
 

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Discussion Starter · #33 ·
Might want to pull each and every fuse including the big ones in the underhood box and test them with an ohm meter. Sometines they can look OK and be fried.
I tested every fuse with a power probe and swapped around every relay including the ones on the body relay block too see if anything would change at all and got nothing, including changing out the dash relay block entirely, its definitely not a bad fuse at this point
 

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All of your symptoms are exactly what the guy at the end of his video is so proud show. No DRL, dash illumintion only when the healights or parking lights are on.where the Daytime Running Lights have been hacked to disable. Check the DRL relay for a bent pin, or the yellow wire cut or the DRL relay removed or the DRL fuse removed.
The radio, headlights, cluster gauges (except for voltage and oil psi) dome lights, and footwell lights will not come on unless the headlight switch is turned to the on position,
If I press the dome light button override button repeatedly it can cause everything to shut off
whenever I turn the headlight switch to "on" power comes back
 
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