Project V8 RX-7: Part 7 – Bringing the E-ROD LS3 to Life (Almost)!

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The relay/fusebox is pretty good size, but we found a good place to cram it just above the Wilwood clutch master cylinder we carried over from our old LS1 swap.

 

We found a nice piece of aluminum plate just about the right size to bend and make a nice mount to attach our relay/fusebox to existing bolt holes in the frame.

 

Our relay/fuse-box snug between the frame, strut tower and brake booster in the engine bay.  Note the bent brake lines that were in the way (with the pink stripe around it).. they’ll need to be shortened and relocated before we can put the hood back on.

Fuel pump wiring

Wiring for our new pump was straightforward.  Just connect the E-ROD harness’ gray wire labeled “fuel pump” to the positive side of the fuel pump and ground the other.

Cooling fan wiring

As we mentioned earlier, the stock Mazda fans have dual speed operation.  Unfortunately, the E-ROD computer doesn’t have provisions for dual speed fan control so we chose to just run our fans on the “High” speed.

The only problem we ran into using the Mazda fans was in our E-ROD fuse/relay box, which has a single 30 amp fuse and wiring suitable for powering a single fan—not two.  The fix was simple though, we pulled the trigger wire from the E-ROD cooling fan relay, spliced it and ran it to the trigger sides of the two Mazda relays used to control high-speed fan operation.  Now we have a spare relay with 30 amps of power available in our fuse/relay box—remember that, we’re gonna need it later!

Gauge Wiring

One of the things we’ve always been adamant about with our swap is retaining all the stock gauge functionality.  The easiest way to do that is to reuse the original Mazda sending units—or at least replicate the signal they want to see to function properly.  So we’ve got 5 gauges to make work: a tachometer, speedometer, oil pressure, water temp and fuel level gauge.  Our fuel gauge should work fine already since we only moved it from one fuel pump assembly to another–so we’re already 20% done!

Tachometer

Our most important gauge—the factory tach—requires a 2 pulse/revolution signal, similar to most 4 cylinder engines and happily also the LS3.  Hooking up our tach was as simple as locating the right wire in the dash harness, snipping it and connecting the gauge side of the wire to our tach signal pigtail from the bulkhead connector.

 

 

 

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