I just finished installing the factory cruise control in my '99 (NB) Miata and thought I would share some observations about installing the various components in an NB that differ somewhat from either what is written in
MASTER SWITCH - There are two variations of this switch in the '99. One is for cars that have fog lights, and it has two push button switches in a single module. The other is for cars without fog lights, and it is a single rocker switch in the same size module. I mistakenly ordered the dual switch, thinking I would eventually install fog lights, only to find that it has a different number of pins than the connector on my non-fog wiring harness. Unless you want to do some cutting and splicing, order the right switch!
Also, if you are replacing the factory blank with a master switch, I would NOT go to the trouble of trying to release the blank by squeezing the hook clips from behind. It's nearly impossible to get to without dismantling lots of things in the way. Instead, I would pry and 'worry' the thing out from the front, even if you have to break it a little. You will find the connector for the new switch living in the back of the blank. Simply unplug it from the blank, plug it into the new master switch, and push the switch back into the rectangular hole, making sure you install it right side up. Once it clicks into place, it's there for good!
VACUUM SERVO - Installation is very much as described, except that there are only two fasteners - one bolt that goes into a threaded hole in the fender and one nut that goes on a stud that's already there. The servo I bought (on ebay) had five rubber grommets on its mounting bracket, but only two were used for mounting purposes. The others simply serve as additional cushioning. My unit was off an '01 and came with both the actuating cable and the vacuum hose attached (nice). There is a square plug in the firewall that pops out, along with a square knockout in the fiber insulating mat inside that is easy to push out. The cable simply snaps into this hole and can live there indefinitely until you're ready to deal with the pedals. There is also a support stud on the cable housing that snaps into a diagonal square hole on the inboard side of the brake fluid reservoir. The vacuum hose goes across the upper firewall and plugs into the back of the intake manifold. Mine had a little rubber stopper covering the fitting on the manifold which I simply removed. What was a little confusing were a couple of support studs on an insulating sleeve that came on the vacuum hose. I couldn't find any holes that would accept these, so I went on ebay where you can find pretty good engine compartment shots of just about any car they might have for sale (good to remember). Anyway, I figured out that the '01 had the cable routed slightly different from the '99, and I simply used tie wraps to secure my hose in a manner that appears to be correct for my model.
CONTROL MODULE - The module installs exactly as described. If you have a Workshop Manual, it will lead you on a wild goose chase where you have to remove the key interlock mechanism. I have no idea what that's about, as this is nowhere near where the module mounts. I think it must be a misprint. The 'HOLD' indicator is actually a 'CRUISE' indicator on NB's (to the left of the fuel gauge), and it requires no special wiring for it to work!
STALK CONTROLS - This went pretty much as described with some minor variations. I chose to remove the air bag and the wheel. It's really not hard at all. The air bag comes off with just two 10mm bolts on the NB. I find that if you loosen the big nut on the wheel without completely removing it, you can then give the wheel a few good jerks to free it from the spline without shifting its position. After that you can center it carefully and gently remove the nut and the wheel. Next is the clockspring, and as long as you're careful not to turn it after it's removed , you won't have any problems. What was the biggest problem for me was removing the bottom panel under the steering column. It is secured by 2 Phillips screws near the bottom edge of the dash, and two 10mm nuts that are fairly difficult to get to. I found that the one on the left was easiest to access through the fuse access hole after I loosened the fuse block and pushed it out of the way. The nut on the right can be reached (with some difficulty) from behind the bottom edge of the dash. I used a small 10mm combination wrench on both. Once that cover is off, the connector is easily accessed, and the cluster switch is simple to swap out with the new one.
PEDAL ASSEMBLY - This proved to be the most challenging for me, as there were some differences in the assembly I bought on ebay and my existing unit. I decided it was going to be too much trouble to change out the bracket and both pedals (gas & brake), so I decided to make the newer fuel pedal work in the old bracket and simply replace the old stoplight switch with the newer stoplight/cruise switch. The problem was that the newer bracket had nylon bushings where the gas pedal pivoted and my bracket didn't. Newer NB owners shouldn't have this problem. The holes in my bracket were the correct diameter for the pivot rod, but no room for the bushings, and the old pedal didn't use a circlip to secure it. Instead it had a 'top hat' (for lack of a better term) press over the end of the pivot shaft. This had to be pried and 'worried' off with considerable foul language. After I got it off and tried to insert the new pedal shaft in the holes, I found that there was too much side play, as the bushings in the newer bracket were shouldered and gave some side support. So, I had to find two washers that fit reasonably well over the pivot shaft and were about a thick as the shoulders on the nylon bushings. That did the trick. The only challenge after that was putting the circlips on the pivot shafts of the pedal and the secondary 'cruise arm' without losing them. I found that needle-nosed pliers worked well for this. Don't forget to put the pedal spring on (as I did) before you install the circlip. Oh, and the nylon bushings for the secondary 'cruise arm' fit perfectly in the original bracket. The cables simply snap into the pedal arm and the cruise arm, and I did that last.
The stoplight switch is easy to replace, and the new one should be adjusted far enough into the bracket that the switch plunger is completely (or almost completely) compressed when the brake pedal is released. If you don't do this, the cruise will not engage. Oh, the little two wire cruise connector can be found tucked away about 10 inches back up the stoplight cable. It took me 20 minutes to find it. It plugs into the stoplight switch next to the stoplight cable.
Finally, it's worth mentioning that the clutch switch that prevents starting without depressing is also tied into the cruise circuit, i.e. nothing to do here. It's already done. If you depress the clutch pedal, the cruise disengages.
I would reckon that my total time for this installation was about 8 hours, but part of that was due to the fact that I was/am slow, and I was having to discover quite a few things on my own. I'm very please with the end results. The cruise control performs exactly as you would expect from factory unit. Anyone interested in doing this mod is welcome to email with questions.
--Geary Morton '99 Emerald Mica