Dual 630 Relay Power Harness HD
Quick Overview
- Two independent 40A circuits — separately fused, relayed and triggered
- Sealed 630-series relays and fuse holders, rated for under-hood use
- 10 AWG copper throughout with 12 ft output legs to reach any load
- Isolated relay coils — switch the positive or ground side, your choice
- PCM safe with internal coil suppression; no external resistor or diode
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$99.99
per EACH (USD)Dual Circuit Universal Power Harness
Two Independently Switched 40 Amp Circuits — Heavy Duty 630 Series
Item #: DRPH-001HD
Product Overview
The DRPH-001HD delivers two completely independent 40-amp power circuits from a single battery connection. Each circuit has its own fuse, its own relay and its own trigger wire, so the two can be switched separately, run from different control sources, or paired as redundant feeds to a single critical load.
Anything drawing upwards of 30 amps — an external fuel pump, a pair of cooling fans, an electric water pump, driving lamps — puts a load on factory wiring that it was never engineered to carry. This harness moves that load onto 10-gauge copper fed straight from the battery through 3/8" terminals, with every connection, fuse and relay clearly labeled.
Sealed 630-series relays and high-temperature loom make it suitable for permanent under-hood installation on a daily-driven car, not just a race application.
Wire Identification
Every wire in the harness is labeled. Circuit 1 and Circuit 2 are functionally identical and interchangeable — assign them to whichever loads suit your installation.
| Wire | Gauge | Function |
|---|---|---|
| Red | 10 AWG | Circuit 1 switched positive output to load |
| Blue | 10 AWG | Circuit 2 switched positive output to load |
| Black ×2 | 10 AWG | Ground — two 48" wires joined at a single ring terminal |
| Red | 20 AWG | Circuit 1 relay coil positive |
| Black / pink stripe | 20 AWG | Circuit 1 relay coil negative |
| Blue | 20 AWG | Circuit 2 relay coil positive |
| Black / light blue stripe | 20 AWG | Circuit 2 relay coil negative |
Wire colours follow the circuit. The relay carrying the 10 AWG red power wires is controlled by the red and black/pink coil pair; the relay carrying the 10 AWG blue power wires is controlled by the blue and black/light-blue pair.
Nothing is commoned internally. Each relay coil has its own positive and its own negative wire, so you can switch either side: feed the coil positive and ground the coil negative through a switch, or hold the coil positive at +12V and let a PCM pull the negative to ground. The two circuits can even be driven from different control sources.
Harness Layout & Lengths
| Battery to fuse holders | 36" — 10 AWG red and blue, terminated in 3/8" ring terminals |
| Fuse holders to relays | 12" — 10 AWG red and blue |
| Relay output to load | 144" (12 ft) — 10 AWG red and blue, pre-stripped and may be trimmed to length |
| Ground | 48" — two 10 AWG black wires joined at a single ring terminal |
| Trigger wires | 96" (8 ft) — 20 AWG, long enough to reach a cabin switch or engine bay controller |
The 12 ft output legs mean the relays can be mounted at the battery while the load sits anywhere in the engine bay or at the rear of the vehicle, without splicing into the high-current path.
Engineering Specifications
- Two 40 Amp Circuits: Independently fused and independently relayed, for a combined 80-amp capacity.
- 10 Gauge Throughout: Heavy copper on both power circuits and the ground for minimal voltage drop under sustained load.
- Sealed 630-Series Relays: Shrouded, sealed 40-amp relays rated for continuous automotive duty in exposed under-hood environments.
- Sealed 630-Series Fuse Holders: Weather-sealed inline holders on each circuit, shipped fused at 30 amps.
- PCM / ECM Safe: Internal suppression resistors protect solid-state drivers, so the relays can be triggered directly from engine management outputs.
- Fully Isolated Relay Coils: Both coil leads are brought out on each circuit, so either side can be switched — positive-switched, ground-switched, or one circuit each way.
- High-Temperature Nylon Loom: GM specification GMP.PA6.003, rated -40°F to 300°F, covering the entire harness.
- Fully Labeled: Every connection, fuse and relay is marked, so circuits stay traceable years after installation.
- 3/8" Battery Terminals: Direct battery connection at both power input and coil ground.
- Fuse Selection Set Included: Installation kit supplies spare 20-, 30- and 40-amp ATC pairs with matching fuse holder cap labels.
- Installation Hardware Included: Mounting and termination hardware supplied.
Typical Applications
- External fuel pumps requiring redundant or fail-safe power feeds
- Electric cooling fans — a single dual-speed fan, or twin fans on separate circuits
- Electric water, oil and coolant pumps
- Auxiliary lighting — fog, spot or driving lamps
- Any device needing a clean high-current source above 30 amps
Suited to race cars and casually driven street cars alike.
Before You Install
The circuit is rated to 40 amps and ships fused at 30 amps. The installation kit supplies spare ATC pairs in 20-, 30- and 40-amp ratings along with matching fuse holder labels, so you can fuse to the measured draw of your device rather than to the harness ceiling.
Once you have settled on a rating, cut the matching label from the strip and apply it to each fuse holder cap. The caps are opaque, so without a label there is no way to tell what is fitted without opening them — and if you ever change the fuse rating, change the label with it.
Frequently Asked Questions
Q: Can I trigger this harness from my PCM or ECM?
A: Yes. The 630-series relays have internal suppression resistors, so no external resistor or diode across the coil is required. Hold the coil positive at +12V and let the PCM pull the coil negative to ground — the coils are fully isolated, so a ground-switched output drives them directly without risk to the solid-state drivers.
Q: Can I run both circuits to the same device for redundancy?
A: Yes. That is one of the intended uses. Two independently fused and relayed feeds to a critical load such as an external fuel pump means a single fuse or relay failure does not shut the device down.
Q: Do the two circuits have to be switched together?
A: No. Each circuit has its own trigger wire and operates completely independently. You can run them from separate switches, separate controllers, or trigger one and leave the other unused.
Q: The circuit is rated to 40 amps but ships with 30-amp fuses. Why?
A: A fuse protects the wiring downstream of it, so it should match your load rather than the harness ceiling. Most devices powered by this harness draw well under 40 amps, and a 15-amp load behind a 40-amp fuse is effectively unprotected. The installation kit includes 20-, 30- and 40-amp spare pairs so you can fit whichever rating suits your device, along with labels for the fuse holder caps.
Q: Can I shorten the output wires?
A: Yes. The 12 ft relay output wires are supplied pre-stripped and can be trimmed to suit your routing. Keep runs as short as practical to minimise voltage drop.
Q: How do I trigger the relays?
A: Each circuit has its own pair of 8 ft coil wires. Circuit 1 uses red (coil positive) and black with a pink stripe (coil negative); Circuit 2 uses blue (coil positive) and black with a light blue stripe (coil negative). Because both leads are brought out, you can switch whichever side suits your control source — a dash switch on the positive, or a PCM pulling the negative to ground.
Warranty & Support
Racetronix harnesses are considered the standard by which others are judged. Every harness is assembled using our computerized crimp-quality monitoring system and then circuit checked before it ships.
This harness is backed by our Limited Lifetime Warranty to the original purchaser while installed in the original vehicle. Warranty claims are subject to proper electrical diagnosis — part-swapping is not a substitute for troubleshooting.
How to get technical support
Racetronix provides technical support to verified customers through our support forum rather than by phone or email. Request access as soon as you place your order. Approval is handled while your parts are in transit, so the documentation and the people are already there on the day you start the install.
We concentrate support in one place for good reasons:
- Open around the clock. Answers do not wait for business hours or for someone to be free at a desk.
- Knowledge going back to 1999. Installation threads, schematics and diagnoses accumulated since we started, all searchable.
- Moderated and approval-only. No spam and no noise — just customers and our technical staff.
- No attachment limits. Post full-resolution photos of your own wiring and get an answer against what you are actually looking at, instead of a description of it.
- Answers stay available. A solution posted once helps the next person with the same vehicle.
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