Headlight Voltage

[Guest]

The headlight on my 81 1100e is way too dim. It's an H4 60Watt bulb in a square headlight. There's a 3 wire connector, with the black/white being ground and then a white wire and a yellow wire coming from the Check Panel. With the battery charged and reading 12.6V, and with the ignition on and the headlight disconnected, at the connector, the white wire reads 10.8V and the yellow 0V on low beam. If I switch to high beam, the white drops to 6V and yellow goes up to 10.4V. If I plug in the light half way and measure on the blades of the bulb, the white reads only 8.3V with the yellow at 0V. Switch to high beam, and I read only 0.7V on the white and 7.6V on the yellow. Is a headlight voltage of 10.8 adequate, or should I looking for another relay mod (already did the coil relay)? What's going on with the connector? How could it be dropping that much voltage? It opens up and comes apart, so I've cleaned and tightened everything well. Or is the voltage dropping in the check panel, which has LEDs to indicate when a bulb is out?

 

[Brendan W]

Sounds like you have a high resistance in the headlight circuit and possibly a dirty lo/hi switch. The current draw when the bulb is in makes it worse. I would open the plug for the right hand bar switch and see what voltage you have there on the headlight wires.

 

[posplayr]

sounds like multiple problems, dirty conenctions galore and dead battery

I think there might be some posts about what to do.

 

[robertbarr]

Do yourself a favor and just order an Eastern Beaver headlight relay kit, unless you're really, really good at open-barrel crimps & fabrication.

It is, pardon the pun, the path of least resistance, and the results are terrific and permanent. It'll also help other areas of your electrical system, since the headlight current will be re-routed and won't be dropping voltage across numerous impediments.

http://www.easternbeaver.com/Main/Wiring_Kits/H4_Kits/h4_kits.html