I just installed a cruise control system on my 1987 RX-7. The switch does not light up at all (it looks like when the system is turned on it should light up "main" and then light up "cruise").

Also, when I turn the system on , it will not hold at the speed it is set at. Instead, it starts to accelerate and continues to accelerate until I shut it off.

Any ideas what is going on? How can I fix it? Thanks!!

 

Could you tell us if this unit came out of a turbo car???? Or a n/a. Is the unit under the hood vacuum operated or is it one that is electric?

 

The actuator unit under the hood came from a 1990 non turbo. It does have a vacuum hose. The switch and the computer unit came from a 1988 TII. My car is an '87 non turbo. I also have the turbo actuator (without the vacuum hose. Thanks!!

 

ttt

 

Why the ttt?????? This post is over a year old. I trust he put the turbo actuator in and all is well.

 

Sorry for that. I am having the exact same problem and was hoping someone might know the solution. My car is an 88 SE. All my parts are from NA cars. I have checked just about everything and can't find anything wrong. Any ideas?

 

yeah, the wrong switch is plugged in.

 

Sooooo......can he repin the switch to make it work???

Wait a minute. Are you saying you have the same exact problem??? But then you say all your parts are from NA cars. Confused me a touch.

 

Sorry, I was refering to this problem.

The car came with the switch installed but no module or actuator. I figured the car orginally came with cruise and someone swiped the the rest. Any ideas?

 

Sorry, I was refering to this problem.

The car came with the switch installed but no module or actuator. I figured the car orginally came with cruise and someone swiped the the rest. Any ideas? Thanks in advance.

 

Let's just say all the parts are normal for your car. I'd say that if you press the button on the end of the switch to SET the speed and the speed keeps on keepin on going faster.......that maybe the switch is staying engaged after you let go. Maybe next time you try it on a deserted road, and it keeps advancing, try to tap the button/switch and see if it stops speeding up. Maybe even try to pull it outward with your finger nails???

Looking at the diagram in the fsm, it appears that when you push the SET button in, that the switch makes a ground to the Cruise Control Unit. Maybe when you let go of the button, the switch stays pushed in and is making or keeping that ground to the Control Unit even though you let go. I'll mull it over. I believe the fsm online has a trouble shooting guide.

 

That is what it sounds like, either that or a bad switch or bad cruise computer.

 

Just as an FYI, it doesnt matter if cruise parts come from a turbo or nonturbo car. The switch and cruise ECU are the same within series. Series 4 stuff works on series 4 cars, and series 5 on 5 cars.

Actuators, those can be swapped between series. The NA version will work on any NA 86-91, and the turbo version will work on any NA OR TURBO 86-91.

The difficulty some run into is clutch and brake switches for cruise. I have seen non-cruise cars that already had the required double switches already installed on the pedals, and I have seen them that didnt, with no real rhyme or reason. You have to have a cruise switch on both the brake pedal (instead of a single plug sensor on the pedal, you have a dual-plug sensor for cruise) and a seperate cruise switch on the clutch. The wiring is always present for all the connections on all cars.

 

See this jpg??? https://www.rx7club.com/attachment.php?postid=900920

Try this. Disconnect the plug from the Cruise Control Unit. Put a meter on the GO (GREEN/ORANGE) wires socket in the plug. Now push the button on the cruise switch and see if you get a ground on the meter when you do that. You should. Now let the button go. Did the ground showing on the meter go away??? It should. IF not, then the switch is sticking.

 

Trivia......you really don't have to have either switch on the brake and clutch pedal. The cruise will work/engage. The problem is you won't be able to disengage the cruise without turning the cruise off with your fingers or turning the key to off. If you have ever blown or taken out the 7.5 amp fuse in the diagram you'll see what I mean. Use deserted street if yu pull it. My two retrofitted cars with cruise both do not have the clutch switch in the circuit. One should never dump the clutch on either of my cars while the cruise is engaged, or wheeeeee.....eight grand in a nanno second.

 

I have tried transplanting cruise on 89-91 cars and it would NEVER engage until I finally ran the diagnostics on the cruise system and it gave me a brake pedal sensor fault. Then I checked and found out I didnt have the sensor. I got the right sensor and it worked perfectly from then on.

Perhaps the 86-8 cars are not so sophisticated, and will operate without them. I know for a fact the 89-91 will not.

 

NA actuator works on turbo car as well, even under boost. Figure that one out. Freaked me out the first time too...

 

Yeah, but there has to be some long term disadvantage to using a vacuum actuator on a turbo car, or else mazda wouldnt have spent the $$$ to develop an electric version.

 

Yeah. I do the same as CAKE. I put a turbo in a 87na and followed his lead and left the normal na actuator in. No problems to report. I've driven on trips to Corpus and back to Ft Worth numerous times with no problems.

The thing is .......when I'm really out to put my pedal to the metal, I'm never in the Cruise mode. The two just don't go together. But during normal cruise on I35...no problem. I've gotta get out there and give it a try though. Cruise along at seventy and boost up to???? 100 or so and let off and see if it'll return to seventy under cruise by itself.

Don't know nuttin about those series five.