Headlight upgrade - Relay installation
Posted: 14 Jun 2015, 20:42
There has been a lot written about the upgrading of headlights so I thought I would give it a go. I have an 1989 van so H4 headlights already installed but they are not the brightest. The first job was to follow Co Kids wiki on upgrading the power feed to the fuse box. I used 16mm² cable connected to a 300amp splitter box by the battery, new cable run underneath the van to another splitter box behind the fuse box. Fuse box connected to it using the existing cable and supply ready for the relays.
I decided to go for the four relay option, 1 each for the low and high beam for each side. I bought the four separate rely mounts that lock together and also have the option for fuses.
Splitter box in position to the side of the fuse box

Plug removed from the board and the headlight wires separated. These were located in the loom by the headlights and cut off and pulled through

Four brown wires shown are new live feeds from the splitter box for the relays, blue ones are earth feeds.

Live links added to the relay boxes with switch feeds installed

The wiring to the headlights was replaced and new connectors installed

The final wiring of the relays and the relays installed. 2 x 30 amp for low beam and 2 x 40 amp for the high beam

The relays installed in position. It is a bit of a fiddle to get them in this location but keeps them out of the way and dry.

The difference that this makes to the headlights is incredible and all for one days work and around £50.
I decided to go for the four relay option, 1 each for the low and high beam for each side. I bought the four separate rely mounts that lock together and also have the option for fuses.
Splitter box in position to the side of the fuse box

Plug removed from the board and the headlight wires separated. These were located in the loom by the headlights and cut off and pulled through

Four brown wires shown are new live feeds from the splitter box for the relays, blue ones are earth feeds.

Live links added to the relay boxes with switch feeds installed

The wiring to the headlights was replaced and new connectors installed

The final wiring of the relays and the relays installed. 2 x 30 amp for low beam and 2 x 40 amp for the high beam

The relays installed in position. It is a bit of a fiddle to get them in this location but keeps them out of the way and dry.


The difference that this makes to the headlights is incredible and all for one days work and around £50.