tach and sensor

Hello , I am getting ready to install a ccs100 cruise control , and was wondering what is the advantage to using both tach and magnet with speed sensor signals versus just the tach?

A vehicle speed signal (VSS) is preferable to tach. The main difference is what type of transmission the vehicle has. If you have a manual transmission, a specific gear and RPM will equal a specific speed. Changing gears will affect the speed at the same RPM. Using VSS is what should be used for either transmission. Tach is used to monitor engine speed for safety. If the clutch is depressed the engine will rev up and the cruise will see this and deactivate the cruise control. Tach isn't needed for an automatic transmission. Ideally, I only use VSS for either type of vehicle and install a clutch switch to disengage the cruise if the clutch pedal is depressed.

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sparky

Thanks For the info , it is a manual transmission , so maybe I should have both hooked up.

I'd use only the VSS since gear x RPM is not always equal to speed (eg, clutch in or freewheeling overdrives etc, or slipping clutches (LOL)).
That's unless the gears & RPM are used as a redundancy - ie, fall back if the VSS fails, but then IMO the cruise control should alert you.

as stated above tach is more of a safety device. If you have the cruise set and press the clutch in it will disengage the cruise.

I'd assume that is the point of it rather - to ensure its not trying to maintain speed in a low gear or whilst upsidedown.
(Not that I know of purely tach driver cruise controls that require gearbox ratios..)

One other thing, I am using a pickup coil and magnets, so one wire goes to the ccs-100 speed input and the other to ground?

That is correct for wiring the speed sensor.

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sparky

Thanks Sparky, hopefully I 'll get back at this project on the weekend ,and I will let you know how I made out.

Rick

How much voltage should I be measuring through the pick up coil, and it will be AC voltage , will it not?

If it's a coil, its AC voltage will be proportional to rotational speed tho it may peak at some value.

Ok I am not having much success with this. I have already installed a
Zemco model 14 on this thing and all it would do was engage and start to over rev and then kick out.So I figured that kit was probably made in the mid 80's and from sitting around was maybe defective.
So I ordered up just the servo for the ccs-100, because I already had
all the wiring , pick-up coil , and switch in place.It acts the same way!
I'm just concerned about the switch. It has a slide button for on -off.
Three other momentary push buttons. set-increase,resume-decrease, and coast. I can get 12 volts on the set and coast buttons but nothing on the resume. Also there are two little lamps inside the casing ,between the switches ,that barley light up until another green wire is grounded.I did use the coast button , in place for the resume.
Does it sound like I need a new switch?

Ok still not having any success. Using the coil only and still the unit only wants to engage and then rev up and disengage.I might add the red power led is not on all the time, just comes on momentary when I push the set button. Should it be on all the time?
Also pin 10 is for the tach and I would assume I should be getting a negative voltage from the coil. Does that sound right. Can anybody tell me what wire off the ECM I could tap into in order to try that route. It is a 1996 geo metro , with the 1.0 engine
I did swap out the push button switch for the set and resume , and now I have the proper voltage on those inputs.

Thanks Rick

Something I may have overlooked, the on/off switch I have is not a momentary one,so when on it is always 12 volt. Looking at the switch online that comes when you buy the whole kit, looks like it is a momentary. So when you press on , it would give a 12 volt signal ,and
off maybe should be a ground to shut it off?

Rick