Help with wiring please!

[Isaiah92260]

So I have a brand new 120 volt alternator that works great and charges at 14.7, no problems.... But my question is, why does my instrument lights at night dim when I press on the brakes when I'm driving at night? Is that because I have the original wire harness present and I have weak connections? All my alternator wiring I did replace under the hood, I do also have a some what weak batter that gives me 12.3 when the truck is off. I do plan I on eventually replacing my batter and wiring new, just wondering if there is anything I should worry about?

[jtrichard]

probably bad connection most likely in fuse block

[PGSigns]

Also check the wiring you replaced to make sure you have it all where it needs to go. If you show us what you have we may be able to give you more suggestions.
Jimmy

[gmachinz]

GM really didn't allow for much in terms of current capacity with the OEM style bulkhead. What, I believe a single 12ga twin lock terminal all provides all the interior power-only to get rerouted back out for things such as lights....? Yep, not efficient. Have you successfully converted to (I assume here....) an internally regulated alternator? That'd be step 1 in my book.

[chevy_mike]

Clean all connections on all the plugs. Make sure you have good grounds to the body, chassis and engine. These two things solve 95% of most electrical problems in old vehicles.