I See the Light, or I'd Like to Anyway....

[leadrsa729]

Hi All -

I have a 72' 911 with a slight electrical problem. Headlights were working fine, both low and high beam. My rear brake light switch in the pedal cluster went bad, and I replaced it. Now the right hand (Passenger's) headlights on low beam shine slightly brighter than the left hand side (Driver's) side, and even worse - the left hand side completely shuts off when I turn the high beams on. Right side shines great on high beam. I also have the upgraded H4 units on my car, but those are just plug and play, and have been installed for a few years now so I'm not sure what's happening.

Any ideas? Thanks in advance for all your help!

[RWebb]

clean the connections incl. the grounds & fuse connections

you definitely need a relay kit also

[leadrsa729]

Thanks for the info RWebb. Can you or anyone else give me a little more info on the relay kit? Is it available from our host, or does this require wiring something in on my own? If you can't tell I am absolutely worthless with electrics. What is the benefit for implementing such a kit?

[RWebb]

it removes the need for lots of amps to flow via circuitous routes to run the bulbs - you need it bad as you are running high power bulbs

search on relay + headlight for multiple threads

be sure to search up the fix for the unfused wires on the dash switch also - you don't want a fire

[porwolf]

Originally Posted by leadrsa729

Hi All -

I have a 72' 911 with a slight electrical problem. Headlights were working fine, both low and high beam. My rear brake light switch in the pedal cluster went bad, and I replaced it. Now the right hand (Passenger's) headlights on low beam shine slightly brighter than the left hand side (Driver's) side, and even worse - the left hand side completely shuts off when I turn the high beams on. Right side shines great on high beam. I also have the upgraded H4 units on my car, but those are just plug and play, and have been installed for a few years now so I'm not sure what's happening.

Any ideas? Thanks in advance for all your help!

To make your lights shine the brightest you have to make sure that only the smallest voltage drop occurs between the battery and the light bulbs. Use a voltmeter and measure the voltage between the +pole of the battery and each connection along the way to the bulbs. Even small voltage drops, caused by dirty or imperfect connections, can dim the lights substantially. I recently upgraded to H4's and installed relays. The only connections between my battery and the +side of the light bulbs are in-line fuses, the relay contacts, and the bulb connector. I soldered all the connections between the battery and the light bulb socket to ensure good contacts. I like to not use solder connections (instead of quick connects) they are mostly bomb proof. I had bad experience with quick connects under high current flow. Of course all the ground contacts have to be checked also.

[E Sully]

I would start by looking for the Brown ground for the headlight in the left fenderwell. The left and right sides use separate ground wires. I had a poor connection in mine, and it caused the same issue. It may be a coincidence that it started acting up when you worked on the brake switch. It also would not hurt to check and clean the fuses and fuse holders. You can use a pencil eraser to polish them a bit.

[dentist90]

Check your left side bulb... I'll bet the high beam filament is blown. The H4 bulb has two filaments, as I'm sure you're aware. What I learned is that on low beam both filaments are active, but not super bright. On high beam only the high beam filament is active. I'm thinking your left bulb is dimmer on low beam as only the one filament is on, and off on high beam for the obvious reason. Might be a real simple fix.