ArdWrknTrk Posted October 10, 2023 Share Posted October 10, 2023 yep..thank you for the diagram! I also think I may have a bad "new" switch from NAPA. Now the blue wire with tracer that was hot when the lights were turned on is dead and so is the fuse block. So Ill grab one tomorrow to be sure. Thank you so much for your help. Ill hit it again after work tomorrow. Before you go swapping out the light switch check fuse #4 (15A) because that would kill all your lights. It's the tan/white feed wire (circuit 195) that usually has a pigtail meltdown. You're hot on its heels. I'm sure you can figure it out tomorrow! Link to comment Share on other sites More sharing options...
pcsteve70 Posted October 12, 2023 Author Share Posted October 12, 2023 Before you go swapping out the light switch check fuse #4 (15A) because that would kill all your lights. It's the tan/white feed wire (circuit 195) that usually has a pigtail meltdown. You're hot on its heels. I'm sure you can figure it out tomorrow! Jim, Well the good news is I found it! It took opening up the harness and physically tracing the instrument circuit. I located a ground wire off of an aftermarket radio harness improperly tied to the same circuit. The wire was assumed to be "ignition on" but clearly not correct. I was able to use a volt/amp meter with resistance to ohm out and trace each load which is how I pinned it down to the radio. Making some repairs to the harness is the next step. Then I get to assemble my interior. I am super happy I have lights again Thank you very much for all of the info! Link to comment Share on other sites More sharing options...
Gary Lewis Posted October 12, 2023 Share Posted October 12, 2023 Jim, Well the good news is I found it! It took opening up the harness and physically tracing the instrument circuit. I located a ground wire off of an aftermarket radio harness improperly tied to the same circuit. The wire was assumed to be "ignition on" but clearly not correct. I was able to use a volt/amp meter with resistance to ohm out and trace each load which is how I pinned it down to the radio. Making some repairs to the harness is the next step. Then I get to assemble my interior. I am super happy I have lights again Thank you very much for all of the info! Congrat's! Well done! Link to comment Share on other sites More sharing options...
ArdWrknTrk Posted October 12, 2023 Share Posted October 12, 2023 Jim, Well the good news is I found it! It took opening up the harness and physically tracing the instrument circuit. I located a ground wire off of an aftermarket radio harness improperly tied to the same circuit. The wire was assumed to be "ignition on" but clearly not correct. I was able to use a volt/amp meter with resistance to ohm out and trace each load which is how I pinned it down to the radio. Making some repairs to the harness is the next step. Then I get to assemble my interior. I am super happy I have lights again Thank you very much for all of the info! Congrats Steve! I'm not sure why anyone would tie a ground to that wire. The main cab ground is right there next to the radio. Give me a minute and I'll post the diagram.... Link to comment Share on other sites More sharing options...
pcsteve70 Posted October 12, 2023 Author Share Posted October 12, 2023 Congrats Steve! I'm not sure why anyone would tie a ground to that wire. The main cab ground is right there next to the radio. Give me a minute and I'll post the diagram.... So.... Im the idiot that did it ! Here's the best part Jim I am an electrical contractor by trade and CLEARLY know better. I removed the old radio and installed a new unit about 3 months ago. It worked just fine. However I am working on the truck and not really driving it so I never turned on the headlamps. On the new radio harness the black and brown wire is the ignition "on" . The BLACK wire is grounded in the unit. My 52 year old eyes missed the fact I tied the ignition wire to the ground harness . I'm such an idiot. Link to comment Share on other sites More sharing options...
ArdWrknTrk Posted October 12, 2023 Share Posted October 12, 2023 So.... Im the idiot that did it ! Here's the best part Jim I am an electrical contractor by trade and CLEARLY know better. I removed the old radio and installed a new unit about 3 months ago. It worked just fine. However I am working on the truck and not really driving it so I never turned on the headlamps. On the new radio harness the black and brown wire is the ignition "on" . The BLACK wire is grounded in the unit. My 52 year old eyes missed the fact I tied the ignition wire to the ground harness . I'm such an idiot. Don't beat yourself up. Y/B is hot in run & accy for the radio. I assume you also need constant 'keep alive' power for settings and memory? Link to comment Share on other sites More sharing options...
pcsteve70 Posted October 12, 2023 Author Share Posted October 12, 2023 Don't beat yourself up. Y/B is hot in run & accy for the radio. I assume you also need constant 'keep alive' power for settings and memory? Correct..... the radio has both a constant hot and a trigger ignition connection. It was grounded through the frame and speakers so it worked just fine. But when the headlight switch was activated...well we all know what happened. In my world BLACK is a current carrying conductor. In DC circuitry, it is typically a ground but it can carry current as you stated when tracers are applied. I should have known better this was first year stuff. I just had brain fog. Luckily I didn't smoke anything. Link to comment Share on other sites More sharing options...
ArdWrknTrk Posted October 12, 2023 Share Posted October 12, 2023 Correct..... the radio has both a constant hot and a trigger ignition connection. It was grounded through the frame and speakers so it worked just fine. But when the headlight switch was activated...well we all know what happened. In my world BLACK is a current carrying conductor. In DC circuitry, it is typically a ground but it can carry current as you stated when tracers are applied. I should have known better this was first year stuff. I just had brain fog. Luckily I didn't smoke anything. If you're 52 you've probably been working with "black=hot" for 30 years. It's no wonder your brain went there automatically. 💡 Fortunately you didn't let the smoke out of the radio or the harness. I've been a contractor with a few cabinet shops over the years. I'm familiar with both single phase residential and three phase (208 & 480) in star and delta for the oddball assortment of machines I've owned. Some of those use black as neutral. Things can get 'spicey' when you've got 40A at 480! 🤯 Link to comment Share on other sites More sharing options...
pcsteve70 Posted October 12, 2023 Author Share Posted October 12, 2023 If you're 52 you've probably been working with "black=hot" for 30 years. It's no wonder your brain went there automatically. 💡 Fortunately you didn't let the smoke out of the radio or the harness. I've been a contractor with a few cabinet shops over the years. I'm familiar with both single phase residential and three phase (208 & 480) in star and delta for the oddball assortment of machines I've owned. Some of those use black as neutral. Things can get 'spicey' when you've got 40A at 480! 🤯 Ha... yes they do. 480v is not to be taken lightly! Link to comment Share on other sites More sharing options...
ArdWrknTrk Posted October 12, 2023 Share Posted October 12, 2023 Ha... yes they do. 480v is not to be taken lightly! It's a lesson you may not live to learn! The cigarette lighter (460 Y/LB) is hot at all times and close enough to the radio for constant power. Link to comment Share on other sites More sharing options...
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