How do I wire a headlight relay

[Ole Petter]

Hi I wish to add a headlight relay to reduce the volgate going through the column mounted light-switch. But I can't find any info on how to wire it...
Thanks for help!

[kodioneill]

Headlight Relay Kit
This easy-to-install kit uses factory connections and mounting points. With the relay kit, the electrical current travels straight from the battery to the headlight circuit at the fuse box, greatly reducing the load on the headlight switch and the failure prone column switch. In addition, more power is supplied to the headlights for maximum light output.

Fits 911 (1974-89). Maximum 100 watt bulbs recommended.

JWST-911-HLPR

Headlight Relay Kit, 911 (1974-89) [Photo] [Photo]

this is a great deal, instructions included. sold by our host.

[Paul K]

It's an easy install, kit comes with instructions. You might also want to do a search here, as there have been several threads on this subject.

[HarryD]

Originally Posted by Ole Petter

Hi I wish to add a headlight relay to reduce the volgate going through the column mounted light-switch. But I can't find any info on how to wire it...
Thanks for help!

Ole Petter,

What is the year of your car. The kit they are referring to is good but the design is for post 1973 cars. If you have any early guy (like mine) some addtioninal thinking is needed since the wiring is slightly different. If you can read a wiring schematic, you can find an old post of mine where i show what I did. Depending on your year, you may need to make some adjustments.

The basic method is to use the signal from your stalk to energize the coil (pin 86) in the relay. The other side of the coil (pin 85) is grounded to complete the circuit. You add a fused circuit (from the battery) to your common contact on the relay (pin 30) and the wire to the headlamp is connected to the normally open contact (pin 87) of the relay.

[dshepp806]

Easy,..easy!


..

Doyle

[RSBob]

Relay numbers:

85 = to ground
30 = to battery (with a fuse between the battery and the relay)
87&87 = to lights/accessory you are powering
86 = power from headlight switch or other switched source

besides the fuse between that battery and the relay, be sure to also add fuses immediately after the relay to your 87s, to insure you are well covered. Your battery fuse should be able to carry twice the power than your individual 87 individual fuses.

I just upgraded my H4s with 85/100 watt bulbs. As a result I had to run new high, low beam, and ground wires/fuses/relays. I used (edit: 12 gauge wire, NOT 20) to handle the increased current. Used a 20 amp fuse between the battery and the relay and two 10s (for high beam) 15/7 low beam. I also added ceramic high-temp connectors from the new wires to the bulbs. Be sure to upgrade your ground wires as well as your hot wires, or you have only done only half the job.

I built my own wire assemblies and they are as refined as I could make them but they are still a bit clunky. Bet I spent about $90 on wire, relays, fuse holders, fuses, connectors, etc, (but I wanted high quality stuff) so a preassembled units may be a good option.

[HarryD]

Originally Posted by RSBob

Relay numbers:

85 = to ground
30 = to battery (with a fuse between the battery and the relay)
87&87 = to lights/accessory you are powering
86 = power from headlight switch or other switched source

besides the fuse between that battery and the relay, be sure to also add fuses immediately after the relay to your 87s, to insure you are well covered. Your battery fuse should be able to carry twice the power than your individual 87 individual fuses.

I just upgraded my H4s with 85/100 watt bulbs. As a result I had to run new high, low beam, and ground wires/fuses/relays. I used 20 gauge wire to handle the increased current. Used a 20 amp fuse between the battery and the relay and two 10s (for high beam) 15/7 low beam. I also added ceramic high-temp connectors from the new wires to the bulbs. Be sure to upgrade your ground wires as well as your hot wires, or you have only done only half the job.

I built my own wire assemblies and they are as refined as I could make them but they are still a bit clunky. Bet I spent about $90 on wire, relays, fuse holders, fuses, connectors, etc, (but I wanted high quality stuff) so a preassembled units may be a good option.

Rick,

I hope you made a typo and meant 12 gauge not 20 gauge wire!

Per my sources:

10 gauge - 480 watt capacity
12 gauge - 360 watt capacity
14 gauge - 300 watt capacity
16 gauge - 216 watt capacity

[Ole Petter]

Many thanks for your knowledge!
I have an old Hella relay, and I would prefer to use that to buying a new set with wires and all.
So many thanks for the info. I guess it is pretty staight forward, but there was no info printed with the relay, so it was great to get it here from you!

I have opened the column stalk once and bent the internal switch, but it didn't last long and now the full beam is no longer working. So I will try and install the relay and then try to fix the column stalk one more time.

[kodioneill]

you should use at least two relays

[Ole Petter]

Use two relays? One for dipped beam and one for full beam?
Does the Pelican kit offer two relays?

[scottb]

The kits come with relays, wires, instructions. They're almost foolproof. For the money, it's just not worthing messing around with a "home brew" kit.

[RSBob]

Harry great catch - before I burned some one to the ground! 12 gauge is correct. Edit to original post as well. Harry, thanks again for the initial help.

[HarryD]

Originally Posted by Ole Petter

Use two relays? One for dipped beam and one for full beam?
Does the Pelican kit offer two relays?

They do. The wiring will end up somewhat like this (ignore the circuits for fog and driving lights):



The fuse numbers will change depending on what year your car is.

[Ole Petter]

Many thanks!
I do see the wisdom of getting the kit from our host....!
Probably not worth trying to do this on my own.