Speedometer & Mile counter

[jm110105]

At times it works and others it just leaves me guessing, and if that isn't frustrating enough, when it shuts off, it doesn't allow the mile counter work, which ok cool, I won't have a lot of miles on it for resale, woo-hoo, but I also don't know when to change the oil or anything... can someone help me?

[shorod]

Maybe, what year is your Mountaineer?

-Rod

[mountainman1]

oil change every 3 months since you can't read counter....

[shorod]

It looks like, from your profile, that your Mountaineer is a 1998. Trusting that's correct, your speedometer and odometer get their information from the Four Wheel Antilock Brake System (4WABS) unit, which gets its vehicle speed information from the two front and one rear wheel speed sensors. The 4WABS unit provides the speed information to the instrument cluster as well as the cruise control module.

Does your cruise control work when the speedometer/odometer stops working? If so, then your problem should lie between the 4WABS unit and the instrument cluster. If not, you might have a code for the system pointing you in the direction of your issue. If you're lucky, the code will be a powertrain code accessible by one of the commercial scan tools. These codes can be read for free by most auto parts stores. If they don't report a code, then you may need to have the ABS codes read. This usually isn't a free service, unless you have a friend with an ABS-capable scan tool.

It is fairly common for the rear axle speed sensors on the Mountaineer and Explorer to fail, you could shotgun that and hope it's your problem. According to the note in the service manual, the vehicle speed signal is derived from the rear axle speed sensor.

-Rod