1988 Mustang LX Hatchback - Fox 500 Project - It's Alive!
Paul's High Perfomrance And Littelfuse Wire And Fire The Fox 500
From the August, 2009 issue of 5.0 Mustang & Super Fords
By Dale Amy
Photography by Dale Amy
Wiring a major project like...
Wiring a major project like our Fox 500 may not be glamorous, but not even a GT500-powered T-top hatchback can run without electrons. Here Mike Weber and Jay Harris from Littelfuse begin the process of fitting the company's ISIS Intelligent Multiplex System--a long name for a product that can really shorten a wiring gig.
OK, OK. We know a lot of sand has dribbled through the hourglass since we last checked in on the Fox 500, Editor Turner's seemingly decade-spanning project of conjoining a tired but solid T-top Fox with a hulking GT500-based powerplant from Ford Racing Performance Parts. Trust us, there were good reasons for our time lapse. Part of it was just life getting in the way, but also we were waiting on a couple of product introductions that seemed ideal for this step in our project.
We're thrilled to report that our Ford Frankenstein is indeed alive. The Fox 500 runs--and has even rumbled around the Jackson, Michigan, shop of Paul's High Performance under its own power. It was fun to watch, actually, with PHP's ever-philosophical Karl Roekle driving while sitting on a milk crate in our gutted interior.
At the risk of gross oversimplification--and not counting the suspension, rollcage, and brake upgrades that have made for the Fox 500's solid, safe foundation--our project posed two distinct sets of challenges for the savvy, hands-on PHP crew (as well as our other project partners) to overcome in getting this thing both running and fully functional. The first, and most obvious, encompassed the mechanical or physical issues of trying to bring together a powertrain and platform that are quite literally from two different centuries. We showed you a lot of how that was accomplished in our last installment (5.0&SF, Oct. '08, p. 102.)
The Fox 500 now actually runs,...
The Fox 500 now actually runs, a huge step that would have taken much longer were it not for the introduction of Ford Racing's M-6017-54SC Control Pack 5.4-liter Supercharged, which is engineered to allow quick, plug-and-play installation of FRPP's Condor-based crate engines into nearly any application. The PCM is calibrated specifically for the supplied cold-air kit; the kit's thermostat housing has an integral intercooler pump relay; and a power distribution box, mass-air sensor, oxygen sensors, and even an ETC-style accelerator pedal are all included. It was already installed by the time we arrived, and the process was apparently quite simple, as only seven wires needed connection. We see the control pack as a huge boon to anyone looking to harness one of FRPP's 5.4-liter crate monsters in his or her project. It sure did the job on ours.
The second hurdle was no less daunting, that being how to wire everything to communicate nicely in an electronic sense, 'cause we all know how dependent modern powertrains like the GT500's are on the absolute rule of electrons. Without a processor in command, this baby simply couldn't run. Besides, the editor will probably think it's kind of nice to have, oh, say, functioning headlights and wipers. Put simply, failure on the electrical aspects of our project would have left us with nothing more than an interesting full-scale static model.
As we mentioned, a couple recent products proved to be really timely and efficient. The first of these comes from Ford Racing in the form of its Control Pack, 5.4L 4-V Supercharged (PN M-6017-54SC.) As its name suggests, this is a PCM-centric kit specifically engineered and calibrated to get one of FRPP's 5.4-liter supercharged crate engines (PN M-6007-C54, like ours, or M-6007-TVS, with the TVS blower upgrade) quickly up and running in such diverse platforms as street rods, kit cars, old muscle cars--or maybe even a crazy editor's Fox Mustang. To do so, FRPP modifies a GT500 PCM's electrical harness to the point where it needs no more than just seven wire connections to fully integrate with the intended vehicle (six connections if you don't want to control an electric fan).
Also, the kit's GT500-based Silver Oak PCM calibration is simplified by removal of the anti-theft provisions that normally make it codependent on a Shelby's instrument cluster for engine operation. To prevent evildoers from potentially using such a PCM to circumvent security on a factory Shelby, the programming also specifically requires use of a return-style fuel system for the engine to operate. In other words, attempting to plug this FRPP PCM into a returnless-fuel GT500 would result in a no-start condition. But more than just a PCM and harness, the kit includes everything necessary to make a crate motor run with OEM driveability, right down to an electronic throttle-control accelerator pedal.
OK, so FRPP's kit quickly took care of all aspects of powertrain control, including driving the fuel pumps, but what about the rest of our car's wiring needs? You know. Those little things like lights, wipers, horn, power accessories, instrument cluster, and so on.
When it came to wiring the...
When it came to wiring the rest of the Fox 500, the introduction of the ISIS Intelligent Multiplex System eased a task that no one had been looking forward to, especially because of the terrible condition of our T-top's original harnesses. We used the ISIS three-cell starter kit and added the remote control option. The key to the system is its black boxes: the Mastercell--essentially the controller/brain that takes all switch inputs--and the two Powercells that distribute power to the car's various electrical loads or accessories and are linked to the Mastercell by multiplexing datalink cables.
The two Powercells (top and...
The two Powercells (top and left) handle all the power distribution functions and completely take away any high-amp loads from the car's switches. They basically take battery power and distribute it directly to whatever loads (lights, horn, turn signals, radio, ignition, and so on) are connected to their plug-in output harnesses. Instructions on how, where, and when that power is to be distributed comes to each Powercell through a single datalink cable connected to the Mastercell. The Mastercell (lower right) accepts up to 32 channels of individual switch inputs. Its onboard processor is pre-programmed for one of a number of responses to each input, i.e., it knows that, say, Channel 3 is the reverse-light input, so it's a simple On/Off function, whereas Channel 8 might be the left turn-signal input, so it must apply a flasher function. The Mastercell is also user-programmable. The processor and its software therefore eliminate any need for separate flasher modules in the car. On the Powercells, each channel is protected by its own fuse, therefore eliminating any need for a separate fuse box.
The concept of the ISIS three-cell...
The concept of the ISIS three-cell kit is that you use one Powercell somewhere in the nose to tie into the nearby harnesses powering front accessories (lights, horn, ignition, and so on). The second Powercell goes out back within easy reach of the rear accessory wiring, while the Mastercell goes in the cabin where the harnesses for all the switchgear are close by. That way, about the only wiring that needs to run the length of the vehicle is the single datalink cable from the Mastercell to each Powercell. By the way, having the car's detailed, color-deciphering wiring manual is essential in quickly determining the right circuits to tap.
Electrical loads are wired...
Electrical loads are wired to the blue harness visible here (there's another on the bottom of the Powercell). Each of 10 output circuits is fuse-protected (up to 25 amps) and has an LED to indicate the status of each circuit. The two 8-gauge, red wires are feeding the Powercell through a separate heavy-duty fuse block, which is itself powered directly from the battery (or the starter in the case of this front powercell) via a 4-gauge wire. The yellow terminal, just visible on the Powercell's left side, is on the datalink cable leading to the Mastercell in the cockpit.
This shot of our partially...
This shot of our partially installed rear Powercell--for now, stuck on the side of the Fox 500's hatch-mounted battery box--perhaps gives a better illustration of this ISIS wiring schematic. The 14-gauge wires from the blue harnesses are feeding the electrical loads (all the rear lamps, and so on), the cell is being powered by the two red wires connected to the fuse blocks left of the battery box (which have yet to be connected to the battery lead), and the black-wrapped datalink is meandering to the Mastercell near the passenger footwell kick-panel.
The Mastercell, meanwhile,...
The Mastercell, meanwhile, was methodically being connected (using its 22-gauge input wires) to the switch inputs of all the accessories that the Powercells were now powering. The Mastercell is almost hidden in this shot, resting on the tranny hump forward of the shifter. It will eventually reside in the passenger kick-panel. Given the use of thin, 22-gauge wire, you should be getting the idea that not much current is flowing through them. In fact, with the ISIS system, which is completely ground-switched, heavy current loads no longer pass through the car's various switches. Amperage now flows directly from the Powercells to the accessories, completely bypassing the switches.
This is the driver-side rear...
This is the driver-side rear wheel arch, where the output wires from the Powercell have been connected to all the relevant leads in the existing rear wiring harness. Notice that some of those old harness wires are now redundant, and the harness has been completely severed. The front portion of that harness is no longer needed and will be removed from the chassis; all of its former functions now feed through the single datalink cable from the Mastercell. There are also quite a few output wires still available and unused, in case our tech-savvy editor decides to add a window-rattling entertainment system, for instance.
Think this thing's seen some...
Think this thing's seen some heat? Our Fox had a couple such examples of damage typical of harnesses and switches that regularly see high current loads, such as in ignition or headlight circuits. With ISIS, such loads will no longer pass through the switchgear. We also discovered that some of our switchgear, like the turn-signal/high-beam stalk and the HVAC controls, were simply worn out and will have to be replaced as we go along. New gear is already on order from our friends at Latemodel Restoration Supply.
This electrical spaghetti...
This electrical spaghetti of wire, fuse box, harness connectors, and flasher modules is just a small sample of the stuff no longer needed in the Fox 500 after installation of the ISIS Intelligent Multiplex System. The guys from Littelfuse say that a typical Fox wiring harness runs about 70 pounds, whereas the ISIS three-cell kit is less than 15. If you're contemplating a similar project, or building a hot rod, kit car, or race car, you really need to check out this ISIS gear.