Our Fox Mustang is a worn-out 30-year-old magazine project car. It needs obvious upgrades like paint and body, plus less tangible items like a total upgrade of all lighting; both interior and exterior.
One of the leaders in LED lighting technology is Diode Dynamics. They not only design and manufacture custom LED lighting solutions for the current generation Mustang (and several other popular performance car lines) but offer direct replacement LED bulbs in virtually every popular incandescent bulb size used in common automotive bulb fitments. To that end, we researched all the original incandescent bulb numbers and locations on our 1990 Fox Mustang and were able to easily order direct replacement LED bulbs from Diode Dynamics for everything from the dome light to the taillights. For our headlights we did opt for a plug-and-play HID solution, but everything else we ordered was LED. While available, we did not order LED replacement bulbs for our dash or map light, as our new Dakota Digital gauge cluster and Daniel Carpenter reproduction map light already arrived with LED illumination built in.
Starting at the back of the car we removed the hatch trim panels to access the taillight area. We ordered LED bulbs to replace the tail/brake (red), turn signal (amber), backup (white), and side marker (red).
Earlier Fox Mustangs used a standard 1157-style bulb (push and twist) for the tail/brake location, but the later years updated to the 3157-style bulb, which has a plastic base and snaps in with a retainer. To remove the bulb, release the retainer wire with a small pocket screwdriver or pick tool.
We’re installing Diode Dynamics’ HP11 3157 tail/brake bulbs, which are rated at 310 lumens of light. Note this does not directly correlate to the lumens of a 3157 incandescent bulb, but it is brighter. Plus, as we mentioned earlier when it comes to braking the LED bulb lights up quicker, so you get that much more notification time for the person behind you when you hit the brake pedal.
While at the rear of the car we installed new 1156 turn signal bulbs with HP11 amber LED equivalents
as well as new 3157 backup light bulbs with HP11 white LEDs.
Often missed at the rear of the Fox Mustang are the side-marker bulbs. These little guys illuminate the side of each taillight since the actual taillight does not do so. Original incandescent bulbs are the popular 194 bulb number, which Diode Dynamics has in multiple options. We chose the HP3 LED bulb in red (note you always want your LED bulb to emit the same color as the lens it passes through).
As we reinstall our hatch trim it was a simple job of popping in our replacement LED unit in place of our incandescent cargo lamp. The SML8 44mm long loop-style LED bulb is the perfect replacement. Not shown here we also dropped a HP5 Cool White LED bulb in place of the stock 194 dome lamp as well for the interior.
Our third brake light and license plate lights got the LED touch as well. The third brake light on the Fox Mustang uses a pair of 194 HP5 LED red bulbs, while the license plate lights take a pair of 194 HP3 LED bulbs in pure white.
Moving up front the turn signal bulbs were replaced with 3157 HP11 LED amber bulbs…
…While the side markers were retrofitted with 194 HP5 LED amber bulbs. All direct plug-in replacements.
Our final upgrade would be for our headlights themselves. Newer vehicle applications can benefit from Diode Dynamics’ all-new SL1 LED headlight modules, however, for the Fox Mustang’s 9004 headlight bulb Diode Dynamics offers its BiXenon HID headlight conversion kit. The kit features the HID bulbs, direct plug-in wiring harnesses, and high-quality ballast units.
The BiXenon HID bulbs are direct replacements for the stock 9004 bulb and are secured with the stock headlight bulb retaining rings. Twist and pull to separate the HID bulb from the adapter, then mount the adapter to the back of the headlight with the factory lock ring. Finally, install the bulb by pushing in and twisting to seat it. Do not touch the bulb with your fingers!
The new BiXenon HID bulb has three wiring connectors exiting it. Two connect to the ballast unit as shown here. The plugs are male/female and cannot be mixed up.
The remaining connector on the bulb connects to the BiXenon adapter harness. It might not look directional, but the connector is, so do not force it.
The final connection on the ballast connects to the BiXenon adapter harness like so. This plug can be connected either way, so if your headlights do not work at first this connector should be flipped and your HIDs should then work. The single ground wire shown here is optional and is generally only connected if you experience radio interference.
Lastly, the BiXenon adapter harness plugs into the stock 9004 headlight connector coming from the vehicle’s wiring harness.
Testing everything out and our Mustang’s exterior lighting looks great and will certainly help us be safer on the road! The LED interior lighting gives the interior a much more modern feel as well.