H4 low beam issue

[911S Targa]

Been a while……..

I did the full Bosch Euro H4 upgrade years ago. Did the proper upgraded install with new wires, with in line fuses, 4 relays, etc…

Having an issue with my low beam driver side H4. It stopped working a month ago, so I bought replacement 55w\100w bulbs, thinking since it’s been over 10 years of me doing the H4 upgrade on my 76 911S, low beam part burnt out, since my high beams still work.

Replaced the bulbs today, but still have the same issue. I checked the fuse panel, the inline fuse on the upgraded wire, checked the connection to the fuse panel, and the headlight. All looks good. As does the area I have them grounded to.

Could the relay have crapped out ? I’m not sure where else to look for the issue.

Thanks
Bill

[timmy2]

Yes, check the relay coils haven’t burnt up, or the contacts have failed.

[911S Targa]

Not being an expert on that, how would I go on checking that ?

[pete3799]

See if you have power and ground on the control side of the relay with headlight switch on.
Then check for power on the load side.

[911obgyn]

Test light is the easiest way to check for power, meters measure voltage and continuity.

[911S Targa]

Thank you for the info.