Speedometer lying

Not sure why it would be right then wrong. But I would change the speed sensor down by the output shaft of the tranny. Only one retention bolt and should plug right in. Make sure all around the shaft where it reads is clean. Check the wires to that sensor and make sure they are not rubbing anywhere.

 

Yep. Either that or the cluster is going bad. You can send them off and get new stepper motors put in. But I'd try the speed sensor/wiring first.

 

Get a laptop and wire a GPS reciever into it for Navigation etc. On that GPS reciever information should include actual speed.

If the two do not match then your truck is lying because it might have been told to lie to you.

 

Everything and everyone lies in trucking!

 

There is no PM needed in my case, FFE had our trucks 63 for purposes of saving Premiums on insurance. The truck consistently displayed 65. I used what I call the Wisconson clock aka counting off mile markers every certain amount of seconds in the old days of dollar trucking turning a 6 hour run into something like half that.

Anyhow.

The truck constantly FAILED the 65 mph test, we bought a laptop and then the rand mcnally GPS disk and satelltie tracker that improved our ability to find places for shipping and recieving using only the physical address at any time. We found the GPS read out for speed in real time maxed out at 63 on the screen in the corner. Checked against the milemarkers and they stubborn said 63 no matter how we worked the number of seconds against one mile.

Took the truck to the shop with a work order, screenshot plus laptop GPS evidence in real time that the truck was not displaying correct 63 and was showing two miles too slow vs indicated 65.

Safety got involved at that point. They swore us to secrecy becaue FFE pays a great deal of money for the trucks to be limited to 63 and would pay out a great deal more if they were allowed to be turned up to 65. There is one particular difference, the Presidents Fleet is 71 mph in my day. But you had to use a certain amount of miles etc to make that fleet. The tractor we got at 20 miles brand new was actually decaled for the president's fleet which was removed a week or two later but never set for 71.

In any event, wife and I teamed were able to see that 63 cross country twice a week on the LA to Avenel Run within a few minutes of assigned appointment time for us 63 isnt the problem. Just the deception until we had the evidence to show that the truck was not performing at the expected 65. (If it was really 65 why are we late 20 miles from delivery? Huh?)

We went on to bigger and better things from that year, overall the 63 mph incident is just a lesson in savings for a large company more than what it is shared with the drivers because they don't ask. Or wonder why they are a few minutes off over a run at 63 instead of 65.

I posted about it before. And I actually still have the satellite reciever and disks that make up the laptop streets USA program which by now will either not update or need so much updating there is no point. It's accurate to around 20 feet or less since Clinton wrote a order causing the Military to improve or decramble the accuracy for civilians. Accurate enough to stay inside a interstate lane in a white out. But need other technology which is a heads up and camera system in near IR or LIDAR to find that deer before your eyes see it.

 

To the lying ffe people...I've got a solution that works....I bought my own dang truck and when my speedo says I'm doing 65, I'm doing 65.