rowden

Hi, cruise control won't work on my car. The cruise motor under the hood is fine, the solenoids all fire with 12V input.
The inputs to the cruise computer all seem to perform as they should except for one. The speedometer output does not vary while driving. It's a constant low voltage of about 1 volt.
What should the ouput from the speedometer be? A change in voltage as the car goes faster? A change in resistance?
Thanks.

slvrghst

iTrader: (1)

TTT... No one????

rotor motor 85

iTrader: (1)

Did you check the vacuum line because in a gsl-se it it vacuum operated there will be a small rubber line coming of of the cruise control on the passenger side under the hood it then goes to a plastic t make sure that there arent any leaks because mine was working fine then it just stopped and thats all that it was good luck

slvrghst

iTrader: (1)

Yes, vacuum is fine, actuator is working, tested brake, clutch, on/off, and the stalk switches all are good. Put in 4 different cruise computers (not knowing if any are good) and still nothing. I haven't tested the speed sensor though nor do I know where it is. Any ideas? Anyone know a way to test a cruise control computer?

Thanks!

74RX4

iTrader: (10)

Factory Service Manual, chapter 15, page 47 has some cruise control troubleshooting info. Mazda has a special checker, but they show resistance and continuity info in this chapter.

If you haven't already, you can download the FSM from one of these sites.
http://foxed.ca/index.php?page=rx7manual
http://wright-here.net/cars/rx7/manuals.html

xXGslseSleeperXx

there is a tsb on that cruise control. mazda actually recalled 1st gens because of that. believe it or not you cant still take it back to the dealership and theyll give you a new one granted that your dealership isnt filled with a bunch of ******** like mine! good luck

rowden

I finally fixed my cruise problem with grounding. The cruise computer behind the drivers seat under the rear deck compartment shares ground with the rear windshield wiper and the rear defrost. I thought my computer was bad, replaced it with two others, then found the ground problem.

xXGslseSleeperXx

Nice!

slvrghst

iTrader: (1)

Tested ground, it's good, computer is also good (tested on a friends car).

Anyone know a test for the speed sensor? My best effort in researching this tells me its on the back of the speedometer. Furthermore, my assumption is that it is basically run with magnets and centrifugal force. Does anyone know if at a certain speed what voltage should be sent to the computer once switch is open? Would a true test be to drive down the road and test for voltage once proper speed is achieved?

FYI: Every other component in the cruise system passed, brake switch, clutch switch, on/off switch, actuator (actuates and holds vacuum), control switch (resume,set, etc), computer.

slvrghst

iTrader: (1)

Anyone!?

slvrghst

iTrader: (1)

Oh Cmon! Someone on here has gotta know something.

xXGslseSleeperXx

i really dont understand wat you mean rite now but the speed sensor is a sensor not a switch, so in asking that, wat switch are you talking about. if a switch is open then obviously it wont see any voltage. the sonsor to keep the speed constant you mean? that runs off vacuum.

slvrghst

iTrader: (1)

You are talking about the actuator. The speed sensor is on the back of the speedo. It regulates the cruise control as well as the speed sensitive power steering. Yesterday I did find a test in the FSM for testing it off the power steering module. I will do that. In the meantime I tested the speed sensor wire at the cruise computer (black with red stripe) and got a continuous 6 volts with ignition on and all the way up to 30mph with no fluctuation. I don't have anything to compare this to though.

xXGslseSleeperXx

i have not pulled up a wiring diagram so im in the wind here but if you have access to a shop computer try all data( even though it sucks) you might find the values, or mitchell. but if not test a working car. my SE is at my other house so i wouldn't be able to give you a value. but bieng that it is a sensor it should give you a varrying voltage and not 6v all the time.( could be shorted sensor is what im sayin) if you can isolate the sensor and test resistance eaisly than i would check that.

xXGslseSleeperXx

once agaian i dont have my diagrams with me so take this with a grain of salt.

jeremyferguson4444

iTrader: (6)

Just spit-balling here, but try checking voltage again over 30mph....Most cruise controls don't work at lower speeds (on my cars anyways).

rowden

I found a fair amount of corrosion on the back of my gauge cluster when I pulled it apart searching for my cruise problem. Cleaning the backplane helped out with my dash lights being inconsistent.

Since you are having to dig so deep to find your problem, I thought to mention it.