94 FD White issue with cruise control not engaging
#1
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94 FD White issue with cruise control not engaging
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?
.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?
#2
Racecar - Formula 2000
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.
Last edited by DaveW; 11-13-22 at 08:28 AM.
#3
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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.
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DaveW (11-13-22)
#4
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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?
#5
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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?
#6
Racecar - Formula 2000
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?
#7
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cruise clutch switch?
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.....
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j9fd3s (11-15-22)
#9
RX-7 Bad Ass
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https://www.rx7club.com/3rd-generati...ntrol-1031871/
^Hit that up, most common failure I've seen is brake switch.
Dale
^Hit that up, most common failure I've seen is brake switch.
Dale
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DaveW (11-23-22)
#10
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https://www.rx7club.com/3rd-generati...ntrol-1031871/
^Hit that up, most common failure I've seen is brake switch.
Dale
^Hit that up, most common failure I've seen is brake switch.
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.......
#11
RX-7 Bad Ass
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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
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
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cardmarc (11-22-22)
#12
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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
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
#13
RX-7 Bad Ass
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
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
#14
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Cruise still wonky
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
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
#15
RX-7 Bad Ass
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
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
#16
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Thread Starter
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
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
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!).
#17
Racecar - Formula 2000
Speed sensor issue?
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.
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.
#19
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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.
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.
Last edited by cardmarc; 11-26-22 at 12:25 PM.
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cardmarc (11-28-22)
#21
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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?
Now on to the NEXT issue. The long suffering balky oil pressure gauge! Has anybody found a permanent fix for that damn gauge?
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DaleClark (11-30-22)
#22
Racecar - Formula 2000
Oil pressure gauge/sender issue
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.
Last edited by DaveW; 11-28-22 at 04:48 PM.
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gracer7-rx7 (11-29-22)
#23
RX-7 Bad Ass
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^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
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