Cruise Control Troubleshooting: Slowly Increases Speed, Abruptly Decelerates, Repeats

[Bob K.]

My '93 Royale developed an odd cruise control behavior. Up to 59 mph, it operates normally and holds speed well. At 60 mph or above, it will slowly increase speed over the course of 20 seconds until it reaches about 7 mph above the set speed. Then, it'll abruptly decelerate to about 5 mph under the set speed. It repeats this constantly. This is exacerbated by hills but also occurs on flat roads.

 

So far, I have:

• Disconnected and inspected the connector to the cruise control module
  
• Replaced the cruise control module
  
• Applied battery power to the pump to check for fine and gross vacuum function
  
• Replaced the vacuum air filter
  
• Checked the cruise vacuum actuator for leaks
  
• Checked the cruise vacuum actuator throttle cable freeplay
  
• Removed, cleaned, inspected and re-greased the speedometer mechanism in the front wheel and the speedometer cable.
  

 

I've been through the service manual troubleshooting procedure but haven't yet discovered the problem. Any suggestions on how I might track down this gremlin?

[Chaharly]

I wonder if the little speed sensor in your speedo is going out? Do you maybe have another cluster from a royale to try? Also when was the last time you lubed and adjusted the freeplay on your cables? That, to me, made the biggest difference

[Bob K.]

Cables have been lubed and checked and double checked. Speedo unit in front wheel was removed, cleaned, and regreased. Speedo cable was regreased at both ends and along its length.

 

The service manual says #61 is the speed sensor. Is that a little black relay up behind the headlight somewhere or is that something inside of the dash cluster?

[Bob K.]

I've answered my own question with some responsible searching. The "speed sensor" is a reed switch inside the instrument cluster.

https://www.venturerider.org/forum/showthread.php?128643-Cruise-control-not-working

 

I've been through the entire service manual cruise control troubleshooting procedure...twice now. No smoking guns. I disassembled and cleaned the cruise control switch at the right handgrip. We'll see if that does something.

[Patch]

My '93 Royale developed an odd cruise control behavior.

1) Up to 59 mph, it operates normally and holds speed well.

2) At 60 mph or above, it will slowly increase speed over the course of 20 seconds

3) until it reaches about 7 mph above the set speed. Then, it'll abruptly decelerate to about 5 mph under the set speed. It repeats this constantly.

This is exacerbated by hills but also occurs on flat roads.

 

Page: 7-157

 

So far, I have:

• A) Disconnected and inspected the connector to the cruise control module
  
• B) Replaced the cruise control module (item 10)
  
• C) Applied battery power to the pump to check for fine and gross vacuum function ( " " 12)
  
• D) Replaced the vacuum air filter ( on 12)
  
• E) Checked the cruise vacuum actuator for leaks (item 13)
  
• F) Checked the cruise vacuum actuator throttle cable freeplay (item 14) (pages 7-157, 3-83, 2-13,14 & 15)
  
• G) Removed, cleaned, inspected and re-greased the speedometer mechanism in the front wheel and the speedometer cable.
  

 

I've been through the service manual troubleshooting procedure but haven't yet discovered the problem. Any suggestions on how I might track down this gremlin?

 

Good post problem well explained.

In troubleshooting we would refer to the above as a "hunting problem" I suspect 3 things.

Item 3 above seems to me to be a discount reading or mechanical moment where calibration is lost or over shot.

 

1st you must follow the cables run making sure there are no twists binding or incorrect adjustments or the system will struggle at first then over shoot the target which then kicks the control logic into to wild cycling.

There could be a load issue attributed to force and or counter forces which may be cabling or actuator under load! What that means is consider the throttle position and loading applied to the actuator which is suitable for well tuned cabling but, could overload the actuator as both the position and drag increase!

 

The only way I know for certain to check vacuum actuated parts is by applying vacuum. For this you need a pump or fab one using a spray cleaning bottle head! (that is a pump) When you actuate the actuator it must hold position for a length of time; if you suspect it or the setup the immerse in a dish of water then check to listen for water in the diaphragm or actuate to squeeze it out - either way you must try to apply some counter force to the business end of the actuator, if it moves under vacuum then it must return to the last position or it is week/defective!

 

You mention new pump, but what about the tubing between? You can again check with vacuum but, visual inspection proves only that you don't see the obvious or just replace the tubing.

The speedo must run smoothly if it jumps at higher reading the system will crash. You need follow the test procedures for the speed sensor pages 7-166 & 167, however I would take it a step further

I would 1st follow the book if it checked out I would then disconnected the cable at the wheel and spin it using a chuck at first slow (make sure the need lifts not backs down) then work my way up past 60 MPH keep it there (ignition on all switch to run bike on center stand) engage cruise! Follow the readings to see if there is any interruption!

{I don't think I missed anything in trick the cruise control but if my logic isn't sound please post a correction}

 

All this is of course assuming you haven't already solved the problem;)

 

Patch

[Bob K.]

Great ideas, Patch. The vacuum hose and vacuum actuator work well and are in fine shape. I can pull a manual vacuum on them and it'll hold indefinitely. The actuator cables are adjusted well and the slightest vacuum will actuate the throttle linkage and begin turning the throttle grip. Excellent idea to spin the speedometer cable with a drill. I'm going to go try that right now.

 

What speed sensor test are you referring to? I'm aware of this one but it's in the Venture cruise troubleshooting procedure, not on pages 7-166 & 167 in my book.

 

I don't see speed sensor tests or speedometer cable tests anywhere else in the book.

 

My speedometer needle was slightly wobbly before I performed maintenance. Last year I disassembled, cleaned, and greased the front wheel speedometer mechanism & the speedometer cable. The speedometer needle on the gauge now runs very smoothly and linearly.

 

Has anyone else ever driven the speedometer cable with a drill? I was surprised...it makes a noticeable noise in the cluster. Not the common 'moan' or squeal from a lack of lubrication but rather just a rotational vibrating sound.

Edited June 17, 2019 by Bob K.

[Patch]

The pages are correct as to my service manual, a paper back one.

 

Yes as to your screen shot but there is one above in mine as well as more on the next page 7-167.

 

The reason for the drill is to simulate the sensor at high speeds. Yes I have done this, and may have as well on an 86 I can't say for certain but I can tell you it takes 4 hands to accomplish. The trick really is to keep the cable from moving down and out of the speed; some a e-clip that holds the cable some down't.

 

Now I do remember that I have parts of a 86 cluster and I did need to scavenge some parts off the second unit to rebuild the tach and speedo, pain in the... job. I did find that the speedo was load but at the end of the effort all said and done the clicking noise was no longer notable.

 

Because you mentioned it works fine at 59 mph, suggests that the overall unit meets functional expectation but it fails at 60 plus,,, so in my mind that is where you should concentrate your efforts.

When I am tracking down such problems I step back and consider the complete unit in operation, break it down into components, then check each one checking it off the list, very much like you did in the OP.

 

This is what would be running thru my mind in your position, it is a resistance problem, what is causing it, magnetic field or mechanical?!

 

Again the bike at 59 will experience the same bumps as it will at 60 mph.

 

I'm around today if you need more feed back

[Bob K.]

No luck today. I performed all maintenance manual troubleshooting steps for the vacuum pump again. Everything worked nicely...activated the vacuum actuator fully, turned the throttle, held the vacuum, released the vacuum. I also disassembled, cleaned and lubricated all the switches in the right handgrip cluster. The problem persists.

 

I spun up the speedometer cable with a drill but couldn't modulate the RPMs on the drill finely enough to watch and operate the cruise system in a useful manner.

 

The system seems to modulate the throttle quickly and nicely, even going up and downhill, up to about 59 mph. Even on steep hills, it'll roll on the throttle pretty hard to maintain 55 mph. As soon as I set the cruise between 62 mph and 75 mph, the system seems sluggish to recover when going up hill (i.e. hesitant to roll on the throttle), and it lazily rolls off the throttle going downhill (which causes the bike to speed up too much and then abruptly decelerate). It's just sluggish all around about 62 mph and above.

 

My next option is to disassemble and check the vacuum pump. Again. Or replace it. Or, find a rotary tool that spins counterclockwise and can be very finely controlled so that I can bench test the system accurately. Or, find a 3rd cruise control unit. Or, inspect the speed sensor.

[Patch]

No luck today. I performed all maintenance manual troubleshooting steps for the vacuum pump again. Everything worked nicely...activated the vacuum actuator fully, turned the throttle, held the vacuum, released the vacuum. I also disassembled, cleaned and lubricated all the switches in the right handgrip cluster. The problem persists.

 

I spun up the speedometer cable with a drill but couldn't modulate the RPMs on the drill finely enough to watch and operate the cruise system in a useful manner.

 

The system seems to modulate the throttle quickly and nicely, even going up and downhill, up to about 59 mph. Even on steep hills, it'll roll on the throttle pretty hard to maintain 55 mph. As soon as I set the cruise between 62 mph and 75 mph, the system seems sluggish to recover when going up hill (i.e. hesitant to roll on the throttle), and it lazily rolls off the throttle going downhill (which causes the bike to speed up too much and then abruptly decelerate). It's just sluggish all around about 62 mph and above.

 

My next option is to disassemble and check the vacuum pump. Again. Or replace it. Or, find a rotary tool that spins counterclockwise and can be very finely controlled so that I can bench test the system accurately. Or, find a 3rd cruise control unit. Or, inspect the speed sensor.

 

 

Not adding up eh... The old drill that had the trigger lock and speed dial?

 

When you are spinning the cable at speed, are you reading the ohms off the sensor?

[Patch]

No luck today. I performed all maintenance manual troubleshooting steps for the vacuum pump again. Everything worked nicely...activated the vacuum actuator fully, turned the throttle, held the vacuum, released the vacuum. I also disassembled, cleaned and lubricated all the switches in the right handgrip cluster. The problem persists.

 

I spun up the speedometer cable with a drill but couldn't modulate the RPMs on the drill finely enough to watch and operate the cruise system in a useful manner.

 

The system seems to modulate the throttle quickly and nicely, even going up and downhill, up to about 59 mph. Even on steep hills, it'll roll on the throttle pretty hard to maintain 55 mph. As soon as I set the cruise between 62 mph and 75 mph, the system seems sluggish to recover when going up hill (i.e. hesitant to roll on the throttle), and it lazily rolls off the throttle going downhill (which causes the bike to speed up too much and then abruptly decelerate). It's just sluggish all around about 62 mph and above.

 

My next option is to disassemble and check the vacuum pump. Again. Or replace it. Or, find a rotary tool that spins counterclockwise and can be very finely controlled so that I can bench test the system accurately. Or, find a 3rd cruise control unit. Or, inspect the speed sensor.

 

 

 

OK this problem is now under my skin!

I went into my shop and dug up what I could find of the 86 dash parts. There wasn't mush left I guess I tossed most of it but I had a close look at the reed switch... After a swipe with alcohol and a tight camera shot of it I found it to be in good condition still in a perfectly closed position.

I pulled out an old phone that has some pics of the speedo I ended up using, there was some noticeable wear on the gears which I lube with synthetic grease and 401 for bushing where the shafts pass thru or end.. the speedo read 61,500 miles

The cup looked like new, I assume the eddy field is also new condition so my opinion time to move past.

 

Some things you mention above are not what I know/remember to be a problem with my 91.

Important to remember that the cruise command can not anticipate a hills elevation, that's your job! On a steep one I would mitt the throttle while still on cruise, then leave off slow to transition back to cruise with a glance at the speedo to know and expect her to level her back to speed!

 

NOT down hill dude, she can not apply the brakes so your momentum will race pass your settings, nothing cruise can do till it begins to slow down!

 

Next yes to on a hill she will be slow to open hard because she can't know the climb so she tries to not over shoot this again is where you need to prep her then she'll likely handle fair enough!

 

You must ALSO consider the gear you are in on a hill moving all that weight, this is when you should gear down to get the inertia up off the crank and all that is attached to it! That is the Pilots job;)

 

I think based on what you wrote last night it is working, not like a modern car or maybe the new bikes but they are a bit sloppy!

 

So you fixed it! You are just not happy with it? But that will change on long, long rides!

 

The End

Patch

[Bob K.]

So you fixed it! You are just not happy with it? But that will change on long, long rides!

 

No, it's not fixed. The problem occurs on flat ground, too.

[Bob K.]

I just finished up a 1,300 mile ride where I used the cruise control extensively. Oddly enough, operation has improved immensely. I'm not getting the same cyclic acceleration and deceleration like I was before and the cruise holds rather nicely even on reasonable rolling terrain. Whatever it was, it worked itself out. Perhaps the speed sensor or a component in the pump was dirty and just needed exercising.

[Patch]

This is the reed switch cleaned, it was quite heavenly coated from oils flying of the cable connector and dust but not likely going to influence its performance.

 

Glad to hear you're happy with it.

[Bob K.]

The silly thing has only gotten better with time. I just completed another 1,300-mile trek. The cruise malfunctioned one time about 10 minutes out of town (disconnect for inability to maintain 65 mph). Then it worked flawlessly the rest of the time. Works throughout all speed ranges, no surging, no lazy operation. It quickly rolls on the throttle going uphill and smoothly rolls off the throttle going downhill. Not a single disconnect. Weird. Maybe the speed sensor was dirty and finally cleared itself out.

 

Patch--How hard is it to get to the speed sensor reed and clean it?