cardmarc

OK, I tried to search on this subject but came up nada
.My 94 has had a recurring issue where the cruise control will not engage/hold. I have had the instrument cluster rebuilt and it is all good, so it's not the circuitry in the cluster (per the wiring diagrams-I have all the books!). I recently installed an Alpine double DIN unit so I had to rewire some of the OEM stuff, but I doubt that had anything to do with the cruise issue. I did suffer a blown 15a tail fuse (which also routes thru the cruise control wiring/cluster per diagrams!) that took down the side marker and tail lights and a few accy lights as well as the cluster lights, but all that is up and running again fine with a replaced fuse. The cruise buttons and indicator lights all work, it's just that it doesn't engage and hold...........
Any ideas what might be causing my cruise to not hold or engage?

DaveW

When I had my dash out to linearize the temperature gauge, I forgot to reconnect the CC on-off button wire when I reinstalled it. Maybe you forgot to hook yours up when you reinstalled the dash. It's a separate wire and easy to miss.

j9fd3s

iTrader: (3)

clutch switch is the likely culprit. there are two, one for the starter and one for the ECU/Cruise control. the ECU/Cruise switch is on top, silver box.

cardmarc

Two clutch switches on the FD MT? I know about one, the starter interlock, as those plastic cushions went bad. I went thru all the tests called out in the 94 body electrical manual, section Q, and all the diagnostics came up fine with the digits. (however none test the clutch switch) I assume you are referring to the switch on page Q-16 and 17?

cardmarc

I think I got those wires all reattached when I put the dash speedo panel in after it being rebuilt........as the lights on the cruise switch all work properly, and the speedometer cruise legend shows up ok when I hit 'set'. It is that the cruise never engages AT ALL when I hit the set button. Did all the tests as well-all ok.......see above about clutch switch maybe?

DaveW

You're correct - for your symptoms it's probably the clutch switch. For me it was connecting the wire I forgot when I put it back together.

cardmarc

I took that silver box clutch switch out and it tested 'good', so I guess it's not that component-and the flash tests also indicated it was ok. I do have a question on the 'pad' that hits it, however. See pic. Is this missing a protrusion that is supposed to hit the white shaft coming from the clutch switch? I also see there is a second brake switch in the cruise circuit, that just cuts the cruise off, which I see happen when the dash indicator goes out, so that switch must be ok. Clutch does the same thing, right? Both are also flash tested and showed 'ok'.
So now after all the testing, still no suspect. I'm going to have to start replacing components........I tried to test the cable actuator motor per -15, but could not obtain the ohm readings the book said it should have, so maybe that is it? I didn't see a test digit flash readout for that component.......(except that the cruise flashes were not there at all per page Q-10?).
The search goes on. Can't imagine what is left.....

tomsn16

iTrader: (283)

I have these cruise components if you need:
Cruise actuator
Cruise control module
Both tested on my '94 and work fine.
All my parts may be returned if not satisfied.....if not needed you are out only the return shipping.
Jim T

DaleClark

iTrader: (55)

https://www.rx7club.com/3rd-generati...ntrol-1031871/

^Hit that up, most common failure I've seen is brake switch.

Dale

cardmarc

Dale,
I read over your write up on the cruise issues.......so even though the cruise light flash tests are 'good' for the brake switch tests (the 07 test ["two switches in the stoplight switch/brake switch are on simultaneously"-????]. and the 31 test (press brake pedal-"defective stoplight switch/defective brake switch"). I got the correct flashes for both indicating they were 'good'. I already removed and tested the clutch switch, now I will again examine the brake switch, but I have my doubts.......

DaleClark

iTrader: (55)

You can bypass the brake switch with a jumper wire to rule that out BTW. Just for testing purposes, NOT for a long term fix.

I finally had to replace my switch. Brake lights would go off and on but the part that registered the pedal position for cruise was not happening. New one solved that.

Dale

cardmarc

It's still quirky. Sometimes cruise works, sometimes not. Mostly not. I took out and tested/lubricated the brake switch, but it does seem to require a lot of inward push to get the cruise contacts to 'react'. I'm going to try replacing it. The pad that contacts this switch-is it supposed to have a 'nub' that pushes in harder on the switch shaft? I have replaced my pad with the Nissan substitutes spoken about elsewhere (for the clutch, etc).

DaleClark

iTrader: (55)

Yeah that switch as it goes in first activates the brake lights then the switch for cruise. Sometimes you can adjust it out a bit so the plunger is pushed in farther, it needs to be damn near all the way in to register the cruise switch.

There was a guy in the classifieds that had a pile of new OEM brake switches for a good price a while back, I got one and it helped out big time.

Again, you can use a simple jumper wire as a test around the block to see if that does it. That will tell you pretty quickly if that's the issue.

Dale

cardmarc

Replaced the brake/cruise switch with a new one. Here’s what is happening; the cruise works the first time I use it (usually) but not after. Sometimes it starts working again for no reason I can deduce. It’s not ‘consistent’ in operation. All the lights work correctly (speedo cruise light) in reaction to pedal pushes (clutch/brake), so I don’t think it’s intermittent wiring issues. What could cause this? I’m now going to replace both the cruise ECU and the cable pull unit (not at once) and see if that changes anything.

DaleClark

iTrader: (55)

Don't throw parts at it, find out the root cause first. I've NEVER seen the cruise ECU or cruise motor go bad.

Next time it happens, try using the top of your foot to pull up on the brake pedal and see if that will hit the sweet spot in the switch to engage cruise. My RX-8 did that for a while.

Again, third time saying this - bypass the brake light switch for troubleshooting purposes. You can just use a jumper wire on the plug for the cruise system so the brake lights will still work. Problem fixed? There you go, brake light switch. Not fixed? Go deeper. But hands down that is the most common culprit and even if you just replaced it it may not be adjusted properly so the switch is fully depressed. Or the brake switch rubber stopper isn't pushing on it fully.

Dale

cardmarc

Jumped out the new brake switch cruise portion. It's not that. Both brake and clutch switch are 'good'. The brake pedal is adjusted so the shaft is fully pushed in when the pedal is up, so the (newish) cushion is flat against the switch housing protrusion-can't push the shaft in any more.
Again, it's an intermittent 'not engaging' thing, EVEN THOUGH the cruise light is 'on' in the speedo. Pushing either the clutch or the brake makes the cruise light go out. It's something else. Don't think it is the 3 buttons on the steering wheel because they work (when the cruise is engaged, and for all the other functions when the cruise is working), It's so strange cruise engages sometimes but not ALL the time upon command of the steering wheel switch (even tho the cruise light comes on!).

DaveW

I have a maybe dumb question: what does the FD cruise module use to sense speed? Is it possible that whatever that is has gotten weak and is not registering that the car is moving fast enough to engage the cruise control?

I know I've had that issue on aftermarket CC systems where the sensor was just a hair too far away from the magnet on the driveshaft and caused similar issues to yours. So maybe the wheel or driveshaft speed sensor has an intermittent issue picking up the speed signal.

tomsn16

iTrader: (283)

As you run out of options remember I have working Actuator/control for $125 + ship. If not your problem you can return.

cardmarc

The cruise uses a tranny mounted speed sensor that sends pulses to the cruise ECU (and speedometer). Accord to section Q light blink tests, my speed sensor is ‘ok’ (gives no error code). But is it? Who knows. The cruise control will not activate below 25 mph, btw. The speed sensor is a basic part of the system.
in searching for related links, one poster stated that his issue was one of the switches INSIDE the cable pull motor assembly. Not sure how it got that thing apart, it’s sealed. I have a spare unit for that part, I will swap it out today and see if that makes a difference.

Pete_89T2

iTrader: (4)

I'm pretty sure it's by design that cruise doesn't activate below 25MPH or so. That was the case with my FC and pretty much all OEM cruise control systems have a minimum speed lockout.

cardmarc

ok, all, I found the problem. It was the under the hood cruise actuator cable unit. Replacing that unit has made the unit work correctly every time. It was NOT the clutch or the brake switch, nor any other issue. And NONE of the section Q cruise light tests led to this issue at all....even tho there is a test for the actuator! So don't trust those tests. In any case, as another owner advised, the actuator has a couple switches in it that may go bad intermittently. The actuator unit is a plastic case plastic welded to a face plate and is difficult to disassemble without destroying it, methinks. So thanks all for the advice and troubleshooting pointers. Grateful for this group!
Now on to the NEXT issue. The long suffering balky oil pressure gauge! Has anybody found a permanent fix for that damn gauge?

DaveW

Clean or replace the sender - it's notoriously easy to plug the small hole that oil enters through. I've cleaned mine with carb-cleaner and air pressure several times.

DaleClark

iTrader: (55)

^Yep, there's a thread going on that topic right now. If the sender is most likely original just get a new one from Mazda, they aren't too pricey.

Dale