Headlamp's Enhancement Relay Wiring

aba4430 · May 22, 2020

The headlamps on my 87 Brat are not the brightest at this time. In 2016 I upgraded to Hella kits for the high and low beams, but did not add relays etc. I have been looking at adding an under hood relay kit (see attachment) and had a couple of questions:

Would it be better to also upgrade the under dash headlamp relays at the same time (reference Loyale 2.7 Turbo's article from several years ago)? Or would it be overkill?
Any input into wiring of the 4-lamp system depicted on page 1 of the attachment? Do the high and low beam grounds etc. look OK? I like how terminal 87a from relay 1 feeds the battery to terminal 30 of the second relay for the high beams.

The lamps on the Brat are the ones linked below. Thanks in advance.

High Beam

Low Beam

Headlamp Relay Instructions.pdf

Numbchux · May 22, 2020

Adding relays like that takes the load off the factory system. The existing relays will only be triggering the new relays, so no need to upgrade them.

The diagram looks largely correct. Subarus typically use a switched ground system (I'm not sure about EA81s, but everything newer certainly does). Meaning the existing wires listed there will be grounded, not powered. Which means you'll need to reverse the polarity of the relay (pin 86 will need a power source, instead of ground).

I'm doing essentially the same thing with my 4Runner right now (as part of a larger project). Mounting underhood relays, running shorter runs of larger gauge power wires to the relays. The voltage drop through ~35 year old factory connectors and relays is pretty severe under load.

aba4430 · May 22, 2020

This is good information. Appreciate it.

Marc556 · May 23, 2020

it is exactly what I need...

I received my Brat from Australia, but before I register the car, I must change the headlights and the fog light.

But here in Europe, it seems very difficult to find?

When I check the links given by aba4030, only the high beam kit can be sent in EUROPE..... and the price for the shippment is $86.

Where can I find a low beam kit ?

aba4430 · May 23, 2020

It is the same kit. You can use it in a two lamp or 4 lamp system. Some wires are not used. Separately, you can make this kit with a couple of Bosch relays, some 12 gauge (or no less than 14 gauge) and 16 gauge wires (relay trigger) and suitable connectors. The kit should be nice, but if the shipping is that high, not worth it. Here is a document with relay wiring diagram for several applications.

12v-relay-common-uses-with-wiring-diagrams-installation-guide.pdf

aba4430 · June 2, 2020

I received my relays, blocks and wiring over the past few days and am now waiting for the block terminals to arrive. The relays and blocks are Bosch, wiring is Ancor and terminals are Hella. I will be adding relays to my headlamps and have added some trivial relay sourcing information here:

1. You can get these relays at a decent price from FCP Euro. The two types I obtained are:

2. The blocks are:

Bosch relay block

Will be making my own wired blocks. The relay with dual 87 terminals will be used for the headlamps and possibly replacement horns (?). The multipurpose relays will be used for other general upgrades and or replacements. I have already replaced my under dash single and three under hood original gold toned AC relay's with the multipurpose ones. Have also received an 11" Spal fan as replacement for my aux fan that has been making terrible noises occasionally. Will need to figure out how to wire this with a relay. I believe the auxiliary fan may already take power from the battery via the under hood relay(s).

Spal 30100411

Will update suitably.