Can the servo cause the speed to surge up, and drop back down constantly. I have a 1993 Ford Ranger with 4.0l, std trans. The cruise does work, but it constantly will surge up about 5-8 mph, and then drop back off. doesn't matter if your on level ground. This makes me crazy, as not to be able to find the cause. HELP

 

It shouldn't be the actuator/servo.
But test vacuum hoses

It is powered by vacuum, but speed is set by speed amplifier(brain) and it is using 8,000ppm(pulses per mile) as a baseline so is pretty accurate and responsive to any changes in vacuum, so if vacuum increases it would just change vacuum solenoid position, it would be almost instant.

On the trans tail shaft will be the speedometer cable hook up, it will also have a VSS(vehicle speed sensor), that sensor is used for cruise and computer.
Check connector for water intrusion or corrosion.

Cruise control doesn't "know" what speed is.
When you press "SET" button it gets the PPM from VSS at that moment, and then tries to keep the same PPM by adjusting the throttle via the actualtor

If PPM is drifting then so would Speed

It could also be speed control amplifier

 

Thank Ron, I haven't found any sign of vacuum leak, and all other parts have bee replaced. I will check the connector at the tail shaft. Someone told me it could be the signal ring in the rear end, if it has gotten warped a little.?

 

1993 doesn't have a Tone Wheel, in the way you were told, 1998 and up did.
1993 still used speedometer cable for the speedometer, so has a Drive gear on the tail shaft and the a Driven gear in the speedo cable hook up, like all vehicles have used since 1940's

Ford added a VSS sensor to this setup
Image here of what it looks like in the trans: http://www.pirate4x4.com/forum/attac...xle-speedo.jpg

Image here of what a new one looks like, gear removed: http://www.therangerstation.com/tech...peedsensor.gif

This first image would have been from a 1995 to 1997 vehicle, I can tell because speedo cable hook up wasn't used, it is very dirty inside, lol.
Starting in 1995 all Rangers got electronic speedometers, no more speedo cables after that, but same housing was used until 1997, and 1999 on some models

Starting in the late 1980's Ford added the VSS to speedo cable housing and technically there is a Tone Wheel inside that housing so it could be damaged, but I would suspect very erratic signal not just drifting to higher speed

You can replace this housing just use your current gear on the new one so speedometer stays accurate.
And you never said but I assumed speedometer is reading OK no jumping of the needle or other odd behavior indicating a problem in the housing or cable?

 

Hi Ron, yes sir checked the housing, and cable and re-oiled, it also has a new VSS. The speedo seems to be fine hooked my cordless drill to and seemed to operate smoothly. also replaced the amplifier to no change.The servo seems to be my last resort but I hate to buy one to continue the same process.

Stumped...

 

You could test the VSS signal at the amplifier, for wiring issue

The VSS is a Variable Reluctance(VR) sensor, it self-generates an alternating current(AC) voltage as the Tone Wheel spins.
You could hook up a volt meter, set to AC volts, at the amplifier wiring harness and watch voltage as you maintain a stable speed, same speed where it "drifts higher"
Unplug wire connector from amplifier for this

Also if you look here: Cruise control not working on 94 ford ranger 4x4. where to start?

There are diagrams with OHMS listed so you can test servo, AND Buttons.
Could be a Button is "telling" amplifier to increase speed, short in Clockspring wire cause changing in OHMS when steering wheel is in a certain position.

SET/COAST/ACCELERATE/RESUME are all done on ONE wire.
When you turn on Cruise, 12volts passes thru the Button Resistors(OHMS) thru the clockspring(slipring) and on to the amplifier on 1 wire.
Resistors lower the voltage so amplifier uses Voltage to tell what buttons are pressed

These are larger images but not sure what year they are for:
http://www.therangerstation.com/tech...ntrol_1of2.JPG
http://www.therangerstation.com/tech...ntrol_2of2.JPG

 

Hi Ron,
Appreciate all the help. I noticed the drive gear in the housing seems like it rotates rather easily Do you know if there is a keyway, or some other means of holding the drive gear from spinning?

 

I have never taken one apart but did find this picture of 2000 Ford Taurus Actuator: http://www.taurusclub.com/forum/atta...n-imgp0034.jpg

I would think it would rotate fairly easy, and plastic gears would most likely be press fit not keyed, but as said I haven't disassembled one.

And even if it slipped on the shaft the "brain" should just readjust it to correct speed/pulse count as it slipped, like going up or down a hill

 

I was able to rotate the drive gear in the transfer case housing through the hole for the speed sensor fairly easy. I was thinking that may be the problem if it turns freely like that Sounds like back to the drawing board..

 

OH, I though we were still on cruise actuator, lol.

Speedo drive gear should NOT turn easily, yes it is on a sleeve that is keyed , picture here: http://thumbs.ebaystatic.com/images/...kEd/s-l225.jpg
They run about $35

Video here on how to change it: www.youtube.com/watch?v=HE4od0S7WcQ

Need a larger socket and new seal but not very hard to change it
Yes you have a BW1354 on your 4x4 Ranger

 

Hey Ron I'll have to get that gear changed and see what happens. I can't tell you how much I appreciate all the knowledge. Thanks again I'll keep you up to date on the progress.

 

One more question, would you have an idea where to find this gear? I am sticking out

 

Transmissioncenter.net sells them: https://transmissioncenter.net/shop/...er-drive-gear/

Also Cobra transmissions

Found this one on ebay: 7 tooth wide OEM Ford Explorer Bronco typeTransfer case Speedometer drive gear | eBay

 

Thanks Ron, I have one ordered and I'll let you know how all goes. Thanks again..

 

Hey Ron,
Again thanks for all your help. I can finally say that my cruise is functioning as new. After ordering the new drive gear I discovered that the yoke nut was not properly torqued from some previous fellow, and it allowed the sleeve of the drive gear to spin on the shaft which galled one end of the sleeve. After replacing the drive gear, and torquing the yoke nut to specs, all is good. The torque is all that's required as there is no keyway or similar type of mechanism. I can't say thank you enough.

 

Good Job Darrell

Thanks for the details on the fix, it will help future readers