Last Updated
15 September, 2004
 


Installing an Auxiliary Fuse Panel

In planning upgrades to my MR2, I realized that many of them would include tapping into the electrical system for power. The SPAL fans, for example, are high-current items, and I was interested in a clean installation. With that in mind, I went looking for an auxiliary fuse panel to power any accessories I would be installing.

I found what I wanted in the Cirkit Boss (Part No. 70207) from Painless Wiring (www.painlesswiring.com). It's small, weatherproof, and has both switched and unswitched circuits. All fuses and a circuit breaker are included.

Space is at a premium in the engine bay, but I found plenty of extra nooks and crannies after replacing the stock air filter and airbox with an APEXi Power Intake.

Finally, remember that this is only a guide -- not gospel. What you do to YOUR vehicle is YOUR responsibility. I do not endorse, approve, authorize, or otherwise encourage you to make alterations to your vehicle. Be careful, and recognize the dangers associated with modifications to your vehicle's critical systems, like electrical, engine, brakes, etc.

Please contact me if you have comments or suggestions about the article or the project, or if you find errors on these pages.

  
Tools Needed

  • 10mm, 12mm, 13mm sockets and wrenches

  • Philips screwdriver

  • Drill, 1/8" drill bit, 

  • Four (4) #10 x 1" Philips-head sheet metal screws with washers

  • Pliers (regular and/or needle nose)

  • Soldering iron & solder

  • Electrical tape

  • Polyethylene cable sleeving (optional)

  • Double-faced tape

  • Sharp knife (an X-acto would be fine)

 
Doing It

Here's a photo of the kit I received from Painless Wiring:
FusePanel-01.JPG (77169 bytes)
I liked this kit. They even print the circuit number on the wire (and whether it's switched or unswitched), so you don't need to keep consulting the (admittedly simple) instructions.

It wasn't cheap (about $70 from Summit Racing), but I think I'll appreciate it in the long run. It's designed to protect your stock electrical components from ill-behaved accessories, and that's what I was looking for.
 

I removed my APEXi Power Intake, which is relatively simple. Loosen the retaining spring on the AFM electrical connector, loosen the hose clamps on the intake hose, remove the bolts on the mounting supports, and pull the entire unit out. Here's the space you'll have to work with:
FusePanel-02.JPG (204938 bytes)
As you can see, I've already identified the area where I'm going to mount the fuse panel. This will be somewhat accessible, yet still leave room for some other devices nearby.
 
I drilled the first hole and attached the fuse block with one screw. I then proceeded to drill the holes for the remaining mounting screws. It's a little tight, but I was able to fit my cordless drill in there, so it was fairly straightforward.

Instead of using the self-tapping screws included in the kit, I used four #10 x 1" Philips-head sheet metal screws with washers under the head.  The thickness of the sound absorbing material on the bulkhead needs to be accounted for, and I preferred having a Philips head vs. a hex head.

Here's a photo of the fuse block after mounting:
FusePanelInPlace.JPG (200987 bytes)
The black connector on the left side of the panel is a relay and socket for the SPAL fans, when I get around to replacing the intercooler.

The kit includes a waterproof cap that fits over the fuses for protection from the elements.
 

Once the panel is mounted, you'll need to run two wires to the main fuse panel (near the left strut tower). Since I wanted a neat install, I removed the ribbed cable sleeving on the main bundle of wires that runs from the bulkhead to the fuse box. I taped the heavy red primary wire and the 18 gauge pink wire to the wire bundle, all the way to the fuse box. 

Afterward, I replace the sleeving with new sleeving. Here's the result:
CableSleeve-01.JPG (159204 bytes)
 

I installed some 1/4" ribbed sleeving from the new fuse panel to the main wire bundle, about 8" in length. I used some scrap sleeving to wrap the leads for the new circuits to avoid any potential shorts, although I guess removing the fuses would be better.
FusePanelFinished.JPG (232881 bytes)
You can see the rubber cap that fits over the fuses, and the short length of 1/4" sleeving on the leads to the main fuse panel.
 
I ran the pink and the red wires all the way into the main fuse panel, taping them down to the main wire bundle along the way:
WireLeadsTaped.JPG (144280 bytes)
 
I ran the two leads up into the main fuse box from the bottom:
WireLeadsinBox.JPG (145335 bytes)
 
The fuse panel kit includes a circuit breaker for use on the primary wire. It has a bracket spot welded to the housing, but I wouldn't be needing it, so I broke it off to save space. Here's a photo of the circuit breaker with the bracket removed:
CircuitBreaker.JPG (39599 bytes)
 
The circuit breaker fits snugly inside the main fuse panel, right where the wires enter the box:
CircuitBreakerPosition.JPG (143541 bytes)
I used a piece of double-faced tape to keep the circuit breaker in place, although it will not be moving around once the wires are in place.
 
I cut the primary lead from the new panel, and crimped a ring terminal onto the end. I did the same with the short length from the breaker's copper-colored terminal stud to the hot terminal in the fuse box. Here are the leads installed on the breaker:
CircuitBreakerFinish.JPG (140702 bytes)
I crimped on a larger ring terminal to the other end connect to the main hot terminal:
hotwire.jpg (125988 bytes)
The red rubber boot fits nicely over the terminals.
 
With the hot lead finished, the only remaining task is locating a lead that is switched with the ignition. The kit includes a "cheater" connecter to attach to a fuse terminal, but I decided to splice into one of the many switched leads. 

Looking down at the connector nearest the edge of the fuse box (at the top of the photo), the black & red striped wires all are switched on with the ignition. Since there is little load on this wire, you can choose any of these:
Connector.JPG (131071 bytes)
 

I chose the wire in the lower left corner. I stripped away about " of insulation, and soldered the pink wire in:
SolderedJoint.JPG (154701 bytes)
I carefully wrapped the splice with electrical tape, and reassembled the connector and closed up the main fuse panel.
 
The fuse panel is now ready for use. I re-attached the parts I had loosened or removed to gain access to the wiring harness, then reinstalled the APEXi intake. Here's a view of the panel with the intake back in place, showing the degre of access I have:
FinishedView.JPG (153662 bytes)
The fuses are easily accessible with the Intake in place, although I will probably remove the intake when adding electrical connections to the panel.
 
 
Dave Martin
1993 MR2 Turbo