Shaking speedometer - Ford Powerstroke Diesel Forum
Powerstroke.org is the premier Diesel Truck Forum on the internet. Registered Users do not see the above ads.
Reply
 
LinkBack Thread Tools Display Modes
  #1  
Old 11-27-2013, 02:40 PM
Compression Ignition Addict
 

Join Date: Oct 2013
Location: Central Illinois
Posts: 1,503
Thanks: 40
Thanked 22 Times in 22 Posts
Feedback Score: 0 reviews
Shaking speedometer

Well, I have a small problem with my 97 F250. When I drive at almost any speed but especially higher speeds (55+mph), the speedometer shakes/moves back and forth. If I'm driving 60 mph it will shake between 58 mph and 62 mph. I think it has something to do with the wide 33" Dick Cepec radials that are on the truck but I have no idea. I don't have an extra set of rims and tires to put on it to test. Any ideas? Thanks and have a Happy Thanksgiving
Reply With Quote Quick reply to this message
Sponsored Links
Advertisement
 
  #2  
Old 11-28-2013, 06:51 PM
Compression Ignition Addict
 

Join Date: Oct 2013
Location: Central Illinois
Posts: 1,503
Thanks: 40
Thanked 22 Times in 22 Posts
Feedback Score: 0 reviews
Pulled the speed sensor...looks pretty rough. I think this is the problem so if any of you have this problem, check your speed sensor first
Reply With Quote Quick reply to this message
  #3  
Old 07-28-2014, 10:48 PM
Powerstroke.org Rookie
 

Join Date: Jul 2014
Posts: 5
Thanks: 1
Thanked 0 Times in 0 Posts
Feedback Score: 0 reviews
Mine still jumps after I replaced the sensor so either the gear is bad or it's behind the gauge idk yet
Reply With Quote Quick reply to this message
  #4  
Old 07-29-2014, 04:59 AM
Compression Ignition Addict
 

Join Date: Oct 2013
Location: Central Illinois
Posts: 1,503
Thanks: 40
Thanked 22 Times in 22 Posts
Feedback Score: 0 reviews
Quote:
Originally Posted by Knger View Post
Mine still jumps after I replaced the sensor so either the gear is bad or it's behind the gauge idk yet
Forgot all about this thread. It wasnt the speed sensor and since it only does it for me in OD, im guessing it is a bad gear.

Sent from AutoGuide.com Free App
Reply With Quote Quick reply to this message
  #5  
Old 07-29-2014, 02:21 PM
Compression Ignition Addict
 

Join Date: Aug 2008
Location: Madison, WI
Posts: 2,925
Thanks: 2
Thanked 61 Times in 59 Posts
Feedback Score: 0 reviews
Except there's no "gear". Speed sensor works like a bike computer; basically a magnet switch. Every time one of the notches on the reluctor (tone ring) passes the magnet, the switch closes, completing a circuit. The PSOM just counts how many times that happens in a given period of time, and translates that to a speed and distance, to drive the speedo and odo, and to send the speed signal to the PCM. That it's only happening in OD is pure coincidence, or perhaps it's actually only showing up when you're going fast enough to be in OD. The VSS is on the diff, and only "knows" how fast the diff is turning; it's not "aware" of anything going on with the transmission. (It works the same, after all, on manual and automatic trucks.) Hypothetically, you could put a truck together with no engine or transmission, just a rear diff and the electrical system and the dash, and push it down a hill, and with the key in RUN, the speedo would work.

One slim possibility is that OD is doing something electrically, that is somehow causing the PSOM not to pick up the VSS signal correctly. But there's no "data" feedback from the PCM to the PSOM, so it would have to be more like some sort of stray voltage or field issue.
Reply With Quote Quick reply to this message
  #6  
Old 07-30-2014, 06:17 AM
Compression Ignition Addict
 

Join Date: Oct 2013
Location: Central Illinois
Posts: 1,503
Thanks: 40
Thanked 22 Times in 22 Posts
Feedback Score: 0 reviews
I think that you are correct about it being an electrical or voltage issue but i have downgraded to 285 tires since and its not nearly as bad as it was before but still shakes

Sent from AutoGuide.com Free App
Reply With Quote Quick reply to this message
  #7  
Old 07-30-2014, 11:14 AM
Compression Ignition Addict
 

Join Date: Aug 2008
Location: Madison, WI
Posts: 2,925
Thanks: 2
Thanked 61 Times in 59 Posts
Feedback Score: 0 reviews
Yeah I could imagine how larger tires could "amplify" the issue. But it shouldn't bounce/shake at all. Dunno if it would shine any light, but you could put the back end up on stands and "drive" it up to speed and see what it does. Even try it with the wheels on / off, to see if the rotational mass of the wheels/tires is a factor. But my money would be on a damaged tone ring, or contaminants in it, or contaminated diff fluid or some such.
Reply With Quote Quick reply to this message
  #8  
Old 07-30-2014, 01:19 PM
Compression Ignition Addict
 

Join Date: Jan 2011
Location: jamestown, nd
Posts: 484
Thanks: 0
Thanked 6 Times in 6 Posts
Feedback Score: 0 reviews
Mine did this was a dirty connection at the sensor only did it hwy speeds


Sent from AutoGuide.com App
Reply With Quote Quick reply to this message
Sponsored Links
Advertisement
 
Reply

Quick Reply
Message:
Options

Register Now

In order to be able to post messages on the Ford Powerstroke Diesel Forum forums, you must first register.
Please enter your desired user name, your email address and other required details in the form below.
User Name:
If you do not want to register, fill this field only and the name will be used as user name for your post.
Password
Please enter a password for your user account. Note that passwords are case-sensitive.
Password:
Confirm Password:
Email Address
Please enter a valid email address for yourself.
Email Address:

Log-in

Human Verification

In order to verify that you are a human and not a spam bot, please enter the answer into the following box below based on the instructions contained in the graphic.



Thread Tools
Display Modes

Posting Rules
You may post new threads
You may post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are On
Pingbacks are On
Refbacks are On



All times are GMT -8. The time now is 07:44 PM.


Powered by vBulletin® Copyright ©2000 - 2014, Jelsoft Enterprises Ltd.
Search Engine Optimization by vBSEO 3.6.1
Garage Plus, Vendor Tools vBulletin Plugins by Drive Thru Online, Inc.

vB.Sponsors