maxima_dumby

Does the cruise applies the brake or does it downshift or what?

noleafclover

why would it need to slow the car down? it keeps it at the same speed. but if you go down a hill, or i guess if you get slammed into the read end real hard, and accelerate naturally, it will just let off on the gas until you go back down to the set speed. if you keep your foot lightly on the gas pedal, you'll feel it moving as the CC is controling it. does anyone know how it actually works?

maxima_dumby

i just want to know how the system works, i mean i didn't noticed the brakes being used when i press the coast button. So i was wondering how the car actually gets slowed down.

eric93SE

iTrader: (1)

The CC pulls the throttle cable, its a seperate cable from the one that attaches to the gas pedle. There is a unit that pulls the cable, I'm not sure how exactly it pulls the cable but I'm guessing its a small stepper motor (It's probably not a very complicated design). The circuit consists of a comparator, it reads in a voltage (that corresponds to the speed that you are traveling at), then it adjusts up or down (in voltage) in order to keep the original set voltage (which is what ever speed you have selected). Typically the simpler the circuit the more reliable it is, so for the car which is in a rather rough environment, the circuit needs to hold up to all the action.

«§»Craig B«§»

iTrader: (5)

hence the name "coast", it coasts and doesn't actually apply any brakes

it's pulls teh throttle cable like eric said, when you hit coast, it just releases some of the tension like if you'd taken your foot of the gas

actuator is just a simple vacuum motor I think

Matt93SE

iTrader: (44)

what craig said.

he's had that thing apart enough, he could probably design another one by now!

but yeah.. when it "slows the car down" all it does it let off the gas and the car naturally coasts back down due to wind resistance and friction on the road.

«§»Craig B«§»

iTrader: (5)

it's working finally!!

For those of you that didn't know what was going on, my cruise died a while back. After changing lots of parts and diagnosing them via the FSM, I finally figured out that it was a combination of bad actuator and the clutch sensor switch needed to be adjusted.
It always thought the clutch was being pushed in so it wouldn't even try to set the speed. Then I fixed that and the green cruise light would come on but not hold speed. The actuator fixed that.
I also replaced the main control unit but I think my old one may have been ok. I may replace it just to test the old one but not right now

Thanks again for all the parts Matt

Taegost

Hrmmm, the little voice in my head prompted me to speak up.
Living in New England, I use cruise alot on the highway, and there are a LOT of hills in the area, and I've also driven thru the Apps a few times in various vehicles.
Now, I realize that most of the time, it does just coast down to speed, but going down a steep hill, I've only seen about 5-15MPH difference, depending on the incline, with cruise, and I've played around with going down the same hills in neutral and drive, and both times, I had to apply the brakes myself to keep from going over that (W/out cruise)
I've also noticed on my mothers' truck, that it does apply the brakes to slow down, and I'm pretty sure it does on the Max too...
But if it doesn't, how then does it keep it within a 10-15MPH tolerance?
Also, is it just me, or does it seem like the Max doesn't like being set at a certain speed? If I don't pay attention to it, the cruise'll creep up on its own... Hehe
Anyhoo, that's my $0.17

supa

where would did u pick up the actuanator???

i think my own is gone...

jason

«§»Craig B«§»

iTrader: (5)

if your actuator is dead, then your cruise light will probably come on for a few seconds when you push the set button and stay green but then turn off after a couple seconds and it wont do anything to hold the speed

I got mine from Matt. The most likely part of the actuator to break is the motor (it's a motor with a cable on the end). If you can find a working one from a junkyard, a VE or VG would work because you can change the cable from one to the other and it'll work (if your cable was ok in the first place). If you cant find one at a junkyard, you can get it from the dealer but it's really expensive.

David

less sophisticated than later ones. Mine does slow down / speed up on hills, but only + - a few mph. I hired a 1998 when I was on holiday in your neck of the woods and the cruise was ROCK solid. Set it at 42mph, and it was like the speedo needle was glued there, even if you were drove up the side of an office block.


r

Matt93SE

iTrader: (44)

only time mine ever wanders more than 2mph from the setpoint is when I'm going up or down hills... when you go down a hill or whatever, it DOES NOT apply the brakes. the only thing the cruise is attached to are the brake light sensor, clutch sensor, and the throttle. the brake and clutch connections are only there to turn the cruise control off when you press either of the two pedals. (i.e. shift your 5-spd into neutral with cruise on, and the RPM will steadily rise as the computer tries to make the car speed up to the setpoint).

as far as accuracy though, mine has always been great- on both my 3rd gens.

94Max

I'm not sure about Maximas specifically, but in general, cruise control systems tend to be more accurate on manual trans. cars than on autos. With the manual, there's a more rigid coupling between the engine & transmission & drive wheels.

Some CCs use engine RPM (sensed from the ignition system) as the input and vary the throttle to maintain that engine RPM. Other systems use vehicle road speed (sensed from driveshaft RPM) and vary the throttle to maintain that RPM.

I've never heard of any cruise control system that applies the brakes (therefore, there can't be any ) Like Matt sez, most systems use a switch on the brake/clutch pedals to turn the system off.

ThurzNite

iTrader: (13)

on my trip between LA and Las Vegas, I set the cruise on my 93 Altima to 75...it varied +/- 5. It was really frustrating catching the car in front of me or losing him (and tailgated from behind). I ended up not using cruise cuz it was too dangerous.
I'll ask my bro to see how his 2k did. Currently, the cruise on the 93 Max 5sp isn't working. No warning lights or anything...just doesn't work. But the cruise light comes on.
Jae

medic

volvo had some cruise system they were working on a while back. not sure if they ever went to production with it, but it allowed you to set a maximum speed and also a following distance (.5 sec, 1 sec, 2 sec, etc)

Bascially, if there was nothing in front of you, the car woud drive to max speed. If someone comes in front of you, the car would slow down to maintin whatever following distance you specify, but still not exceed the speed limit. On this system, I'd figure they'd have to put a brake control on the CC so it could slow down the car fast enough. coasting down a hill or behind someone who cut you off isn't going to be enough in many cases.

again, maybe this was just theoretical since I've never seen it outside of a research article. for our max though, the car does not brake for you; it will downshift for more power up hills and rev/idle the engine when going up/down steep hills. have a friend follow you down a hill with your cruise set. let him tell you if he ever sees your brake light go on by itself.

Badaxxima

I've pulled mine into neutral (w/o using the clutch pedal obviously), but the cruise only kicked the RPM up to 4000, then it stayed there.

Uncle Pete

iTrader: (1)

The 4k limit could be a safety feature. The third gen cruise control is only active between 30 and 99mph, so maybe it doesn't need more than 4k.