What do the relay terminal numbers 30, 85, 86, 87, and 87a mean?

Per the diagram's legend: 30 is the High Power Feed (must be fused), 85 is the Relay Coil Ground, 86 is the Relay Coil Feed (trigger wire), 87 is the High Power Output - Normally Open Contact, and 87a is the High Power Output - Normally Closed Contact.

How many relays does this headlight wiring setup use?

Two relays: a Low Beam Relay and a High Beam Relay.

Where do the relay trigger wires connect?

The trigger wiring is labeled '(To Existing Wiring Harness)', meaning the factory headlight wiring triggers the relays while the battery supplies high-current power.

Does the power feed from the battery need a fuse?

Yes. The legend states terminal 30, the High Power Feed, 'Must be Fused!', and the diagram shows a fuse point (highlighted by a red arrow) near the battery positive lead.

How are the four headlights arranged in this diagram?

Left side: a Low/High Beam lamp and a High Beam lamp. Right side: a High Beam lamp and a Low/High Beam lamp — a typical four-lamp arrangement.

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Headlight Relay Wiring Diagram - Low/High Beam Relays, Terminals 30 85 86 87 87a

Headlight relay wiring diagram with low and high beam relays and terminal guide

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Headlight relay wiring diagram showing low/high beam relays, color-coded wires and a relay terminal number guide.

AI caption June 2013 · Photo 714 of 1042

This document is a wiring diagram showing how to add relays to a vehicle's headlight circuit. It depicts four headlamps — a Low/High Beam lamp and a High Beam lamp on the left side, and a High Beam lamp and a Low/High Beam lamp on the right side — wired through two relays labeled 'Low Beam Relay' and 'High Beam Relay'. The relay trigger wires connect '(To Existing Wiring Harness)', while high-current power is fed from a DC battery (a red arrow in the image highlights an inline fuse/connection point near the battery positive feed). A central chassis ground symbol serves the headlamp grounds. The diagram includes a 'Relay Wiring Guide and Terminal Numbers' legend explaining standard relay terminals: 30 is the high power feed (which must be fused), 85 is the relay coil ground, 86 is the relay coil feed (trigger wire), 87 is the normally open high-power output contact, and 87a is the normally closed high-power output contact. Wire colors shown include red (power feed), green, black, and tan/orange traces for the relay and lamp circuits. A reader can learn the general layout for converting factory headlight wiring to a relay-powered setup with direct battery feed.

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Frequently asked questions

What do the relay terminal numbers 30, 85, 86, 87, and 87a mean?: Per the diagram's legend: 30 is the High Power Feed (must be fused), 85 is the Relay Coil Ground, 86 is the Relay Coil Feed (trigger wire), 87 is the High Power Output - Normally Open Contact, and 87a is the High Power Output - Normally Closed Contact.
How many relays does this headlight wiring setup use?: Two relays: a Low Beam Relay and a High Beam Relay.
Where do the relay trigger wires connect?: The trigger wiring is labeled '(To Existing Wiring Harness)', meaning the factory headlight wiring triggers the relays while the battery supplies high-current power.
Does the power feed from the battery need a fuse?: Yes. The legend states terminal 30, the High Power Feed, 'Must be Fused!', and the diagram shows a fuse point (highlighted by a red arrow) near the battery positive lead.
How are the four headlights arranged in this diagram?: Left side: a Low/High Beam lamp and a High Beam lamp. Right side: a High Beam lamp and a Low/High Beam lamp — a typical four-lamp arrangement.