NC2Fair5ltrghia 1 Posted September 12, 2021 Hello, I’m hoping someone can look at my voltage drop test readings on the brake light circuit? I am a bit worried by the readings on the positive wire. I have not done voltage drop tests before but YouTube helped & also did them on my headlights & tail lights to see what’s what. So I got the gist of what’s going on & it seems you should have under the battery voltage once all tests are done when added up & readings should be around 0.5v or less on a positive+ to positive+ or earth- to earth- wire. From what I have learned I have resistance I think in my positive wire but as I have never done this maybe it’s normal on the brake light circuit? I can only think something maybe feeding off that positive for power? I have attached the wiring diagram for EA - ED. Any help would be really appreciated. Thanks I ran 2 tests. Car off was done after other tests & is why voltage is a bit low. For the test when car was running, was done after a drive about 15mins later. Car off Battery voltage: 12.29v Drivers side + batt to + brake light wire: 1.90v - batt to - brake light wire: 0.10v + brake light wire to – brake light wire: 9.90v Total: 11.90v Total of 0.39v under battery voltage Passenger side + batt to + brake light wire: 2.00v - batt to - brake light wire: 0.16v + brake light wire to – brake light wire: 9.66v Total: 11.82v Total of 0.47v under battery voltage Car running Battery voltage: 14.25v Drivers side + batt to + brake light wire: 1.96v - batt to - brake light wire: 0.23v + brake light wire to – brake light wire: 12.20v Total: 14.39v Total of 0.14v OVER battery voltage Passenger side + batt to + brake light wire: 1.93v - batt to - brake light wire: 0.14v + brake light wire to – brake light wire: 12.06v Total: 14.13v Total of 0.12v under battery voltage Light on rear parcel shelf in rear window + batt to + brake light wire: 2.00v - batt to - brake light wire: 0.40v + brake light wire to – brake light wire: 11.90v Total: 14.30v Total of 0.05 v OVER battery voltage Voltage at brake light switch with ignition on/car off 11.11volts Share this post Link to post Share on other sites
