[NickD]

Ha, that post dates back to 03-17-2012 that caused me concerned. With engine running to get 14.5 volts, check the voltage drop between both the positive and negative battery terminals to their respective terminals directly at the headlamp sockets.

Was only seeing about 0.2 volts maximum, wasn't worth fooling with, unless you got a harness made by some Chinese factory that was cheating.

Incandescent are strictly pure DC, capacitors won't do anything, nothing to filter. Could be a major problem with HID's with some steep current peaks.

If I was seeing a larger voltage drop, like a total of greater than 0.5 volts, GM would have heard from me. Head lamps are only 65 watts, at 14.5 volts only draw 4.5 amps. The one on the right hand side is worst case, has the longer run. Voltage drops can also be in the BCM or the fuse relay box, voltage originates from the battery terminals, so have to pinpoint where these drops are. Also have to check the voltage drops on the dims and the brights, two different circuits.

 

[NickD]

View attachment 183697

For years, GM an other Domestics were using a super fast acting circuit breaker for head lamps, the Japanese started using fast blowing fuses, and for whatever reason, GM copied this. Each head lamp filament has its own fast blowing fuse, and once blown, have to be replaced. They are all in that under hood fuse/relay box along with the DRL point contacts.

GM was using a self cleaning sliding type switch for head lamps. One spec of carbon on these point contacts, won't get that lamp on. The fuses themselves add two more non-molecular touching type contacts, augmented by corrosion due to road salt.

Daytime running lights, complicated the heck out of these circuits, because people are too stupid to switch on their lights when conditions call for it, and if that BCM crashes, its a computer, can loose all of your headlamps. Some guys go nuts trying to troubleshoot these circuits.

But the bottom line, already have fuses, why even add more? Just more problems.