Speedo Problem
- Thread starter PBH
- Start date
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rwinch
Full Access Members
Two questions:
1) What is the year and model of your Expedition? Without this, I (we) have no idea what system you have!!!
2) Has this only happened recently, i.e. during the cold weather.
Also, it might help if you start out to work a few minutes earlier in the morning.....
1) What is the year and model of your Expedition? Without this, I (we) have no idea what system you have!!!
2) Has this only happened recently, i.e. during the cold weather.
Also, it might help if you start out to work a few minutes earlier in the morning.....
2001 Exp. Yes it seems cold weather related. I assume the speedo is a stepper motor, maybe a bit sticky? Seems odd that when I'm travelling 30 MPH the speedo indicate 80 MPH, them later just drops right back to the right point.
I would have expected low readings, not higher.
I would have expected low readings, not higher.
rwinch
Full Access Members
Do you have a digital or analog speedo?
Anyway, I have attached a small file that is the .jpg from a Repair Manual CD I have. It is for my '98, but I think it applies to your model year.
It shows how to check the VSS (vehicle Speed Sensor). Althoughy I do not think it is your problem, it would be wise to test it. The following is the description for the VSS - Speedo operation:
"The vehicle speed sensor (VSS) (Figure 45) is a variable reluctance or Hall-effect sensor that generates a waveform with a frequency that is proportional to the speed of the vehicle. If the vehicle is moving at a relatively low velocity, the sensor produces a signal with a low frequency. As the vehicle velocity increases, the sensor generates a signal with a higher frequency. The PCM uses the frequency signal generated by the VSS (and other inputs) to control such parameters as fuel injection, ignition control, transmission/transaxle shift scheduling and torque converter clutch scheduling."
You can see that if the VSS is not working right, other things would be wrong as well.
Let me know what you find, but I do not think me CD will have your model year speedo on it.
You can get the Repair CD's off of Ebay.
Good Luck!!!
Anyway, I have attached a small file that is the .jpg from a Repair Manual CD I have. It is for my '98, but I think it applies to your model year.
It shows how to check the VSS (vehicle Speed Sensor). Althoughy I do not think it is your problem, it would be wise to test it. The following is the description for the VSS - Speedo operation:
"The vehicle speed sensor (VSS) (Figure 45) is a variable reluctance or Hall-effect sensor that generates a waveform with a frequency that is proportional to the speed of the vehicle. If the vehicle is moving at a relatively low velocity, the sensor produces a signal with a low frequency. As the vehicle velocity increases, the sensor generates a signal with a higher frequency. The PCM uses the frequency signal generated by the VSS (and other inputs) to control such parameters as fuel injection, ignition control, transmission/transaxle shift scheduling and torque converter clutch scheduling."
You can see that if the VSS is not working right, other things would be wrong as well.
Let me know what you find, but I do not think me CD will have your model year speedo on it.
You can get the Repair CD's off of Ebay.
Good Luck!!!
Analog. I assume stepper motor driven . I actually have a Ford repair CD, thanks for reminding me about it. I will investigate abd report back...
Judging by the VSS description if it was not working I would have more than speedo problems, but I will check it out.
There does appear to be a friction issue, the speedo all of a sidden moves about 180 degress and then works fine. I suspect I'll be disassembling my dash over the holidays.
Judging by the VSS description if it was not working I would have more than speedo problems, but I will check it out.
There does appear to be a friction issue, the speedo all of a sidden moves about 180 degress and then works fine. I suspect I'll be disassembling my dash over the holidays.
rwinch
Full Access Members
The VSS is listed in both my Ford Repair CD and the Haynes manual. Besides, the Exby did not come in a Diesel format (at least to my knowledge).
