Cruise control will not hold proper speed
 

Just installed cruise controll on my GTU. Got the the actuator, switch and the unit under the dash. My problem is that the switch lights up, and the cruise light comes when u press the button on the end, but it wont stay at the desired speed when u let off the gas pedal. You let off the gas pedal and the speed drops untill eventually the cruse light goes off. I have a FSM, but it looks like u have a to have an "ACC checker" to properly check it. Is there another method of checking all the components? or better yet, has anybody had this problem before? Thanks in advance...

Sounds like that vac source for the actuator is not correct.

Why are you using cruise control?

That comment is next to useless and should not be posted.

If you are not going to post accurate information, please do not post

The vacuum source is a good place to start. This is a vacuum actuator....not an electric one, right?

Then make sure the cable is actually doing its job i.e. connected at BOTH ends of the actuator.

So it the above is right, go to the actuator.and pull the plug off. See if you have 12v on the Green/Yellow wire when the key is on and the cruise is in Main,.

IF that's good, pull the plug off the cruise control unit near your left foot. Put the meter on ohms, one lead on a good ground. Put the other lead on the blue/red wire. The meter should show a ground when you put the cruise lever to Coast.

Now put your meter on the blue/white wire and put the cruise lever to Resume. You should get a ground when the lever is held to Resume.

Now put your meter to the green/orange wire. Push the Set button to set. Does the meter momentarily show a ground???? This is where I found the fault in my 86 car. The Set switch had falled apart and the guts of the switch fell on the floor of the car.

It would help if you let us know if you even *feel* the cruise pulling in at all. I'm not too clear whether you are even engaging the cruise. Are you pushing the buttons and basically nothing is happening except lights??? Or is it like IceMark suggests......it engages but gradually loses the speed, even though you felt it engage initially.

This is a

Because i'm trying to keep from getting so many tickets :(

Thanks guys, i'll check it out tomorrow and let ya'll know what i find.

thats what a speedometer is for, but i hope you get the cc fixed, for trips and stuff that is:)

Could that be a split diaphram in the actuator leaking vacuum?
This is a what? ;)

Today I checked everything out as described above. Everything checked out good. I checked the vacuum hose and it does have vacuum. I have it hooked up the the one in the rear of the intake manifold, the one that points upward.

And the cruise never enguages at all. When u press the button to set it and let off the gas, the speed just drops untill the cruise light goes off, but the main light stays on. Anymore ideas???

my cruise control is acting wierd too. But it's the total opposite from yours. Instead of just slowing down, mine will actually floor it and accelerate... my boost gauge goes up and all. It wont stop.

Have either of you checked your throttle linkages? There's one for the gas pedal and a second for the cc. I found when mine were out of adjustment the cc engaged sluggishly... I realize that's not quite what you're describing, but I think it's worth a look.

Got me. Here's a jpg of the system. I'd ring the wires out and make sure they are going where they are supposed to go.

Take note that the SET, COAST, RESUME all just put a momentary ground on the Cruise Unit. Make sure that the ground signal goes away once you let the switch go back to its normal position. That especially applies to VITETFC. In his case I'd check and make sure the SET switch is applying a momentary ground when he pushes the SET button, and that when he releases the SET switch that the ground is removed from the Green/Orange wire at the cruise unit. If the SET switch is sticking.....that would expalin his problem. Same with the Resume switch. Make sure the ground signal is removed once the switch is let go.

Also see that Y wire from the Stop Light Sw?? Make sure that that 12v is not there when the brake pedal or clutch pedal are NOT engaged. If it were....then the cruise would not engage.

https://www.rx7club.com/forum/attach...postid=1022159
https://www.rx7club.com/forum/attach...postid=1022159

Also see the Green/Red wire on the left side of the Cruise Unit???? Goes to the Speed Sensor in the Insturment Cluster. You might ring that wire out from end to end if the other wires pan out.

I was betting heavily on the SET switch not putting a momentary ground on the Green/Orange wire at the Cruise Unit. Oh well.

Are you REAL sure you have 12v on the BY(black/yellow) wire at the Cruise Unit when the switch is put to MAIN?????? That should be there all the time after you engage the MAIN switch. It's not momentary. The lights surrounding the cruise unit are from a different source, so don't assume that the 12v is there at the BY wire just because you see some edge lighting on the Cruise Switch.

Just thought i would let ya'll know that i found out what was wrong with my cruise control just incase somebody else out there is having the same problem. It was the cruise control actuator that was bad the whole time. Replaced it with a different unit and it works perfectly. Thanks for all the help...