Rostra cruise control problem, (Pete, I need you)

[David Anderson]

My Rostra model 2501223 cruise control with a 250-3592 dash switch just quit working after I tapped the brake pedal yesterday.  I never could get it to engage again.  I checked to see if my magnet was still attached to the drive shaft and it is.  The distance between the magnet and sensor is 5/8" (within the book settings)

The "on" switch lights up.  The "engaged" light illuminates when I attempt a speed setting when bus is above 35mph.   It will go out when I hit the brake pedal.  All lights work as normal but I have no engagement of the foot pedal by the servo.  

I have not attempted any diagnostics per the book as yet.  I would like to check the magnet sensor on the drive shaft first to see if it is sending signals to the controller at the front of the coach.   Can I ohm out that wire by putting my meter at the controller end and passing a magnet back and forth over the sensor?   I'm not sure how it signals the controller from the drive shaft.   The diagnostic test in the book calls for spinning the rear wheels greater than 3mph.  That's a bit hard to do in a bus.

Pete, if you read this let me know

One other thing.  I pulled the fuse on the controller's circuit and it checked ok.  I reinstalled and switched on the bus battery.  I then turned on the dash switch and I heard what sounded like a gear motor turn for about one second inside the servo box.  The foot cable did not move, however, and I could not duplicate that sound again.    Any idea what that means?

Thanks,
David

[RTS/Daytona]

Hmmm - sound like what ever method you used to secure the outer cable end - may have slipped it's position ?? - Just pull on the INNER CABLE to make sure that there is not a WHOLE BIG BUNCH OF SLACK - this would indicate that the cable mount has slipped -

You said that the engaged light will go on (after 35mph) when you hit SET and off when you hit the brakes (The ENGAGED light feature does not function with that model Rostra you have - unless you customized the wiring ??) - tell me more about this

The Rostra diagnostic instructions - explains the method to check the speed pules - just put the Rostra into Diagnostic mode and watch the "DIAG" light as the vehicle move forward (the pules should be evenly spaced - uneven means it missed a magnet ?? or lost magnet)  - yes your right for safety this usually requires two people

The noise you hear on start up sometimes is the SERVO resetting (that's  normal)

any questions / concerns call me ...386..672..0571..  (Florida time - Please no calls after 9pm - wife goes to bed early )


Pete RTS/Daytona

[David Anderson]

Hmmm - sound like what ever method you used to secure the outer cable end - may have slipped it's position ?? - Just pull on the INNER CABLE to make sure that there is not a WHOLE BIG BUNCH OF SLACK - this would indicate that the cable mount has slipped -

You said that the engaged light will go on (after 35mph) when you hit SET and off when you hit the brakes (The ENGAGED light feature does not function with that model Rostra you have - unless you customized the wiring ??) - tell me more about this

I tried pulling on the inner cable behind my gas pedal and could not pull any out, so no abnormal slack.   I can depress the pedal and the cable moves inside the sheath like normal. 

The engaged light was done with a separate relay.  The wiring was explained to me by a Rosta technition over the phone 6 years ago when I installed the cruise.  I would have to go look at the field wiring to tell you how I did this.  I'll try to do that. 

I may attempt a diagnostic test tomorrow if time allows.  Otherwise I'm off in the coach to our next destination sans a cruise control.

David

[RTS/Daytona]

David

Yes there is a work around for the engage light using a relay - so ok - I understand that "your" engage light works

Because you are actually seing the "ENAGE" indication - my guess is the internal servo and or internal cable attachment is broken

Just Having the engage light go on at the right speed "over 35 MPH" and stay on until the brakes are applied - saying EVERYTHING
is working - except the cable pull components

[pvcces]

David or Pete,

I would like to look at the work around to get our light working, if I can. Could either of you give me a sketch that shows how you hooked it up?

Thanks.

Tom Caffrey

[RTS/Daytona]

Universal Dash Mount Switch 250-3592 - The LED enagage light on  (pink wire)  DOES NOT WORK with the Rostra Global control unit - The light on the switch needs
    +12v to light and the Global Control unit pink (more like orange to me) gives 0v (ground) when the cruise goes active (engaged)

Simple fix #1-take the pink or orange wire from the GLOBAL CONTROL UNIT-to a separate instrument bulb on the dash and bring the other bulb terminal to IGN +12v.

OR

Simple fix#2-take the pink or orange wire from the GLOBAL CONTROL UNIT to a 12v CUBE RELAY COIL (pin 85) - other side of the relay coil (pin 86) to IGN +12v -
relay operating point (pin 30) to IGN+12v - relay normally open (pin 87A) to the PINK wire from the 250-3592 Rostra switch    


I'm pretty sure that there is a way to do this type of signal inversion with a simple PNP transitor MPS2907 from Radio Shack # 276-2023

Help me out here you guys with the electronic backround - I THINK that the base (B) just goes to the Rostra Control Pink/orange wire  - the Collector (c) goes to the pink wire from the switch unit engage bulb circuit and the Emitter (E) just goes to ground - no sure if I need to add any limiting resistors - My guess is that when the control unit goes high the PNP transistor will conduct and send the light circuit pink wire to ground what do you think guys - It's been way way too long for me ??

COMMENT PLEASE

Pete RTS/Daytona

IIRC - the 250-3592 was designed for the earlier Vacuum Style Rostra Cruise Control -

[David Anderson]

Pete,

I crawled under the bus and checked the sender by piercing the two leads with a couple of straight pins and attaching my ohm meter to them.  I ran a refrigerator magnet back and forth and it would ohm the meter each time I passed it by.  I moved the sensor a couple of washers closer to see if it fixes the problem.

I'll be driving to Abilene Tx in a few minutes, arriving about midnight, then leaving at 0dark:30 in the morning heading home to Pleasanton.  Hopefully it will work.  If not then more investigating at the servo will be needed when I get home.

When I get home I'll post a textial description of the engaged light circuit.  I read some of my wiring description last night but I want to look at the field wiring before I post.  It is very easy using a $10 relay.

David

[David Anderson]

Yippee, it worked all the way home.  The sensor reposition did the trick.  Thanks for you help Pete.

Tom, I checked my field wiring and it is as Pete says.  On the relay the orange wire from the servo connects to terminal 85.  The pink wire from the dash control connects to terminal 87.  Run a 12v+ from any hot terminal from your fuse panel to 86 and 30.  Terminal 87a is not used.  The 12v+ needs to go off when you turn the bus off, therefore it is a switched circuit.

I bought my relay at Autozone, about $9.

David

[buswarrior]

Now go back and seal those pricks...

The creeping black and green death will bring cruise control to a halt in the future due to high resistance in your signal wiring.

happy coaching!
buswarrior

[David Anderson]

Now go back and seal those pricks...

Got it.  Thanks

[pvcces]

Thanks, Pete and Dave. I'll print this thread out and get this modification done when I get the chance.

I hadn't seen anything about it before, so this is a big help.

Tom Caffrey