Cruise control, anyone ever put one in?

[Tim]

Awesome, now I know what the next project on my car is going to be. Should make my trip to Baltimore later this year more bearable with cruise-control.

Time to keep an eye out for a Tracer CC system.

I would hedge a bet that many Mazdas use the same essential cruise control parts, namely the brain box and control unit. The switches, wiring and control stalk can be found on virtually any late 80s/early 90s Mazda.

Might be worth your while to poke around a few Mazdas next time you're at the junkyard, Tracers are not the most common car. The brain box, if I remember right, is a gold colored box about size of a Coke can (although a lot skinnier) and is likely mounted under the dash somewhere near the driver's side.


-Tim


EDIT:


Another update!

The more I research things, the more doable plugging the tach wire into the cruise control box seems. 4th gear ratio in a manual is .88 and the speedometer gear is .91...very close to each other. So when you're cruising at 70 in 5th, the cruise control thinks you're doing 55, well within its comfort zone. If you have a 4 speed manual, the tach and speedo will be extremely close to each other in terms of signal output.

Only thing to do now is verify that the reed switch signal is 12v to ground, install the cruise control, and cross your fingers...


-Tim

[Tim]

UPDATE!

Found the wiring diagram for the circuit here: http://www.xsadclan.com/files/323%20...ol-circuit.gif

It's from a 323GTX, but looks exactly as I remember seeing it in the Tracer shop manual.

One side of the reed switch does indeed go to the ground, confirming my suspicions and making FestYboy's suggestion seem even more viable.

The schematic does indicate one wire going to the PCM. If I remember right it was just a 12v "on" signal, which I obtained from the power wire. Probably should double-check that against the schematic though so nothing gets fried...


-Tim

[Tim]

What about this:

http://dx.com/p/hall-magnetic-sensor-switch-module-for-smart-car-141363

Mounted near a magnet on the inner end of the CV shaft? Epoxy the magnet on and fab a bracket to hold the sensor.

If I remember right, a speedometer works off of a rotating magnet generating a force field that moves the needle more or less depending on the speed of the rotation. The reed switch would be mounted close to the magnet. As a result the reed switch closes each time the magnet passes it, at the same speed as the speedometer cable.

So if you're cruising at 70 mph, the tach would be somewhere around 3,000 RPMs. If the speedometer cable at some point between stop and full throttle turns at 3000 RPMs, then 3,000 pulses per minute should be plenty for the cruise control box (even if the car normally goes 30 mph when the speedo cable is going 3000 RPM). The same logic applies to a Hall effect sensor near an axle if the final drive ratio and the speedometer gear ratio are close/overlap enough.


Regards,

-Tim

[crazyrog17]

What about this:

http://dx.com/p/hall-magnetic-sensor-switch-module-for-smart-car-141363

Mounted near a magnet on the inner end of the CV shaft? Epoxy the magnet on and fab a bracket to hold the sensor.

[TorqueEffect]

That definitely did not occur to me at the time! Probably would have made things much easier, lol.

I would have to check my shop manuals and see if the reed switch is grounded on one end (my gut says it was, but I can't remember for sure), or if two wires run to the brain box.

Assuming it is grounded, it's highly probable that it's 12 volts. Even if it was less, a resistor could drop it to the correct voltage. From there it would literally be as easy as running a wire from the tach feed to the brain box.

However, the flip side of the coin is that both sides of the reed switch are connected directly to a microprocessor or something, making things a little more difficult. Tapping directly into the tach wire wouldn't be an option, but a workaround could easily be found. By using an independently-powered 12v relay (so as to not overload the ignition coil), connecting the tach wire to one side and the wires to the brain box to the other, this method could theoretically imitate the reed switch. Probably would be best to use a solid state relay for this purpose as I doubt a mechanical one would last long.

One thing that bugs me, though, is why they didn't just skip the reed switch altogether and tap into the tach signal? No doubt it would have been simpler and cheaper, especially on a mass-production scale.

My guess as to why hinges on this: every position on the speedometer provides unique feedback; ie the reeds open/close at a different rate dependent on speed. Whereas with the tach feed, the signal varies with RPMs, which in turn vary depending on the gear you're in. Also, one must assume the frequency of the pulses from both the reed switch and the tach signal are close enough to make the system work. Assuming they are, though, tapping into the tach signal gives rise to the following scenarios:

The difference between the tach wire/reed switch seems trivial if you're driving a stick shift; in overdrive you're going to be cruising in the same gear unless you come to a hill and downshift, at which point the cruise control is disengaged either through the pedal switches or the control stalk. After you're back in overdrive, hit resume and all is good.

But in an automatic, I can envision problems if the cruise control was tied to the tach signal. All would be fine until you get to a hill and the transmission downshifts. The cruise control would be confused by the sudden spike in RPMs and probably wig out. The same thing could occur if you were accelerating, but not in overdrive, and set the cruise control. Once the car upshifts to overdrive, the cruise control will read the drop in RPMs as a decrease in speed and accelerate the car to compromise.

I'm guessing the designers foresaw this, and since the Tracer did come in automatic variants, they chose to use the reed switch setup. It would not surprise me if, in typical Mazda fashion, the same basic setup was used in a variety of different vehicles and applications.

So I guess, after digesting all this and assuming the signals are compatible, tapping into the tach wire is the way to go. The vast majority of us drive manual transmissions, and those with autos could easily adapt to the quirks of using the tach feed, as they're pretty minor. Definitely not worth going through what I went through with the reed switch to achieve the same basic effect.

Wish I still had my Festiva so I could experiment and report my findings....



Regards,

Tim

Awesome, now I know what the next project on my car is going to be. Should make my trip to Baltimore later this year more bearable with cruise-control.

Time to keep an eye out for a Tracer CC system.

[Tim]

Tim, why didn't you use the tach feed for the speedo reed switch? essentially the same signal (though the voltage may be different).

That definitely did not occur to me at the time! Probably would have made things much easier, lol.

I would have to check my shop manuals and see if the reed switch is grounded on one end (my gut says it was, but I can't remember for sure), or if two wires run to the brain box.

Assuming it is grounded, it's highly probable that it's 12 volts. Even if it was less, a resistor could drop it to the correct voltage. From there it would literally be as easy as running a wire from the tach feed to the brain box.

However, the flip side of the coin is that both sides of the reed switch are connected directly to a microprocessor or something, making things a little more difficult. Tapping directly into the tach wire wouldn't be an option, but a workaround could easily be found. By using an independently-powered 12v relay (so as to not overload the ignition coil), connecting the tach wire to one side and the wires to the brain box to the other, this method could theoretically imitate the reed switch. Probably would be best to use a solid state relay for this purpose as I doubt a mechanical one would last long.

One thing that bugs me, though, is why they didn't just skip the reed switch altogether and tap into the tach signal? No doubt it would have been simpler and cheaper, especially on a mass-production scale.

My guess as to why hinges on this: every position on the speedometer provides unique feedback; ie the reeds open/close at a different rate dependent on speed. Whereas with the tach feed, the signal varies with RPMs, which in turn vary depending on the gear you're in. Also, one must assume the frequency of the pulses from both the reed switch and the tach signal are close enough to make the system work. Assuming they are, though, tapping into the tach signal gives rise to the following scenarios:

The difference between the tach wire/reed switch seems trivial if you're driving a stick shift; in overdrive you're going to be cruising in the same gear unless you come to a hill and downshift, at which point the cruise control is disengaged either through the pedal switches or the control stalk. After you're back in overdrive, hit resume and all is good.

But in an automatic, I can envision problems if the cruise control was tied to the tach signal. All would be fine until you get to a hill and the transmission downshifts. The cruise control would be confused by the sudden spike in RPMs and probably wig out. The same thing could occur if you were accelerating, but not in overdrive, and set the cruise control. Once the car upshifts to overdrive, the cruise control will read the drop in RPMs as a decrease in speed and accelerate the car to compromise.

I'm guessing the designers foresaw this, and since the Tracer did come in automatic variants, they chose to use the reed switch setup. It would not surprise me if, in typical Mazda fashion, the same basic setup was used in a variety of different vehicles and applications.

So I guess, after digesting all this and assuming the signals are compatible, tapping into the tach wire is the way to go. The vast majority of us drive manual transmissions, and those with autos could easily adapt to the quirks of using the tach feed, as they're pretty minor. Definitely not worth going through what I went through with the reed switch to achieve the same basic effect.

Wish I still had my Festiva so I could experiment and report my findings....



Regards,

Tim

[Chobobulous]

Lol, you had THAT much trouble pulling a harness and wiper stalk?! Me and Karl pulled an entire dealer installed cruise control from an aspire in Columbus PnP in about 20 minutes, including the bracket for the brake petal switch, ecu and vacuum resovoir things. I wish I would have had the cash or it would be hooked up to my 5th gen 626 steering wheel buttons.

It didn't appear to be a complex system at all, the ecu was zip tied to the stock ecu, 3 wires, power ground, rpm, throttle linkage and vacuum.

Anybody with a socket set and a pocketknife can (should be able to) remove a wiper stalk in about 3 minutes.

An aspire cruise control works on a festiva?! That sucks. Ive already seen two of them.

[bravekozak]

Doctor, I am impressed. The only part of the Tracer system I am using is the combination switch. I have already finished the electrical wiring. My only problem is the speedometer cable. I phoned Mustangs, etc. today about the Ford part number for the lower cruise cable and got the wrong part per the diagram in the Ford installation guide. Which makes me want to just shorten the stock cable by three inches. Can you say "surgery". Too bad I can't use stem cells to grow the part I need.

[FestYboy]

Tim, why didn't you use the tach feed for the speedo reed switch? essentially the same signal (though the voltage may be different).

[Tim]

I feel like Dr. Frankenstein today, reviving long dead threads and making horrible monsters out of them...

Anyway, almost 10 years ago(!) I successfully retrofitted the cruise control from a 1987-89 Mercury Tracer to my Festiva. This is about as close to a factory (not dealer) cruise control you will get. It was a fairly easy swap; most stuff bolted straight on with little difficulty.

Making the parts physically fit was the easy part, however. The wiring required a fair amount of creativity and research. Fortunately, the cruise control is its own entity and is not controlled by the ECU. With the help of a factory shop manual, I was able to make my own wiring harness and use the Mazda control stalk and switch, for a factory look.

While hooking this all up, I hit a major snag: The Tracer's instrument cluster has a small reed switch near the speedometer assembly that sends a pulse to the cruise control brain box. The Festiva's cluster does not have this, nor does it have a provision for installing the switch. Initially I thought I could bypass the switch by simply shorting the wires out, but I realized it was not just a simple on/off switch. Rather, the switch opens and closes constantly and a rate determined by the speedometer, which it is magnetically coupled to. This open/closing action sends a pulse to the brain box, allowing it to maintain a constant speed.

After I realized this, I was discouraged. Using the Tracer speedometer in the Festiva cluster was out of the question, it would not fit. My only option was to modify a Festiva speedometer to accept the reed switch, which I did. Regretfully I did not document this part, nor take any photos. Kind of like the KFC secret formula I guess, it's that one ingredient that tied the whole thing together.

I don't recall exactly what I did to get the reed switch to work with the Festiva speedometer, it was largely trial and error. I used a Dremel to carve out bits of the plastic enclosure and circuit board to make room for the reed switch, which thankfully is a very small part. To aid in positioning the reed switch, I wired an analog electronic tally counter (not sure what the technical name is) in series with reed switch. I connected a drill to the speedometer to rotate it while I moved the reed switch around the back of the speedometer assembly. Using the Tracer speedometer as a guide, I positioned the reed switch similarly on the Festiva speed and experimented with it until the tally counter started counting in step with the speedometer while varying the drill's RPMs. Eventually I found a spot that enabled me to get the reed switch to work, as well as provide room for mounting and wiring.

Positioning and mounting the reed switch was the hardest part of the installation. I used a Dremel to grind away bits of the plastic speedometer housing and the circuit board to make the reed switch fit, then Superglued it in place. I don't recall having to cut through and/or jump any traces on the circuit board, but at any rate I got it all back together in my Festiva, and was floored when it actually worked!!!!

So there you have it, cruise control expert level. I was considering unravelling the Festiva's wiring harness, taking the cruise control wiring from the Tracer and adding to the bundle and rewrapping it, but at that point I had working cruise control and I was happy.

If someone replicates this, please document it better for all of us to enjoy!


Regards,

Tim

[Bert]

Anybody with a socket set and a pocketknife can (should be able to) remove a wiper stalk in about 3 minutes.

I was not entirely sure how and what to remove so was careful. But if you can remove a steering wheel and the attendent plastic covers and get the staulk in 3 minutes you are a better man than me. I had the covers and the wheel off in fairly short order. For me the wire looms that connect to the wiper and light stalk on this car were an SOB to get at and to release. I don't even know if a 92 323 system can be made to work in a Festy; the hazard switch is not on the column. Or do I have to disassemble the wiper mechanism from the light switch and then graft it on to a Festy setup?

[zoom zoom]

Lol, you had THAT much trouble pulling a harness and wiper stalk?! Me and Karl pulled an entire dealer installed cruise control from an aspire in Columbus PnP in about 20 minutes, including the bracket for the brake petal switch, ecu and vacuum resovoir things. I wish I would have had the cash or it would be hooked up to my 5th gen 626 steering wheel buttons.

It didn't appear to be a complex system at all, the ecu was zip tied to the stock ecu, 3 wires, power ground, rpm, throttle linkage and vacuum.

Anybody with a socket set and a pocketknife can (should be able to) remove a wiper stalk in about 3 minutes.

[Bert]

The RX-7 cruise switch is a perfect fit for the Festiva dash. Also the Mazda steering column controls with cruise fit right on. The wiring is very simple to provide power through the switch to the steering column controls. I just had to follow the instruction sheet that came with the Ford cruise computer for the other wiring. The hardest part is to find space for the vacuum reservoir and servo valve in the engine compartment if you also have power steering and A/C.
Here is the Festiva cruise install manual that I got from 25horseplay.

Just from trying to remove the intermittent wiper body and staulk plus the integral wiring harness from a 92 323 was already a big undertaking for me a few weeks ago. OEM Cruise control was built-in to the steering wheel that had to be removed. I hate using a hammer and pry bar to wreck otherwise pefectly good pieces of trim but did in this case after 10 minutes of going no-where fiddling while the sun was setting. Mazda doesn't f-around with making sure there are no unsecured wires in and along the steering column. Cruise may be nice but not at all practical if it takes a month of Sundays to scavenge from one car and then re-install on another, IMO.

[bravekozak]

The RX-7 cruise switch is a perfect fit for the Festiva dash. Also the Mazda steering column controls with cruise fit right on. The wiring is very simple to provide power through the switch to the steering column controls. I just had to follow the instruction sheet that came with the Ford cruise computer for the other wiring. The hardest part is to find space for the vacuum reservoir and servo valve in the engine compartment if you also have power steering and A/C.
Here is the Festiva cruise install manual that I got from 25horseplay.

[Bert]

I found a 92 323 LX 5 speed at the JY a few weeks ago that has factory cruise. There is an on/off switch on the dash and then push buttons on the column. Seems like a whole lot of work to put something like that in.