Installing an original cruise control system on a Miata should be very simple—and sometimes it is, but not always. That’s because Mazda cut corners on the wiring in some models.
If you’re lucky, your Miata will come equipped with all the wiring needed for cruise control. In that case, it’s simply a matter of installing all the parts that come with the system.
We’re talking about:
- a main switch that turns the system on or off;
- the cruise control module, the system’s electronic brain;
- the actuator, a vacuum-operated actuator that controls the accelerator pedal via a cable;
- an accelerator pedal with a lever mechanism, to which the actuator’s cable is attached;
- a replacement lever on the steering wheel, used to adjust the set speed;
- a replacement brake switch, which can pause the system after braking.
If all the parts are in good condition and connected to a complete wiring harness, the system should work. In the photo, you can see the main switch on the far left of the dashboard, and the right-hand lever with cruise control functions behind the steering wheel.
However, there are also Miata models in which part of the wiring in the dashboard is missing. I’ve already worked on a few of those. In those cases, the section of wiring where the connector for the main switch is supposed to be is missing, among other things. The wiring for the cruise control module, however, is complete. The wires that branch off from there, however, lead to a dead end, which terminates at the connector that connects the dashboard to the car’s wiring harness. A connection is also missing in a connector on the instrument cluster, preventing the car’s speed signal from being transmitted.
In this video, I’ll give you all the information you need to solve that problem.
The weakest link in the system is the cruise control module, but there are other weak links as well. The cruise control modules are at least 23 years old, and the capacitors inside them can fail. That’s not unusual in itself, and fortunately, capacitors aren’t expensive. The module’s housing is fairly easy to open, and you can immediately see whether one or more capacitors have reached the end of their service life. The top of the capacitors is normally silver-colored (aluminum, I think), unless it has leaked. In that case, the top is partially black, and you’ll see a spot or a small bump on it. That capacitor needs to be replaced. There’s no guarantee that this will solve the problem, but a replacement cruise control module is a lot more expensive than replacing a single capacitor.
If you want to check whether your Miata has all the necessary wiring, or if you want to know how to install cruise control on a Miata, I recommend watching this video.
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