Ford E350 Speedometer Malfunction

by Catlin Tidwell
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Speedometer image by Sirena Designs from

The Ford E350 chassis is used in a number of large vehicles, including vans, motor homes and trucks. Speedometer problems in these vehicles can occur for a number of reasons but are most commonly associated with malfunction of the vehicle's speed sensor, trouble with computer controls or data stored in the vehicle's computers or loose cables.

Speedometer Cable Malfunction

The speedometer is connected to the speed sensor and the vehicle's computer by cables. The speedometer may malfunction of the speedometer cable is knocked loose or if the cable itself malfunctions. Checking for loose connections or replacing the cable may fix speedometer malfunctions.

Change of Tire Size

The Ford E350's internal computer calculates the vehicle's speed based on the speed the wheels are rotating and the size of the tires. If the vehicle's tires are replaced with tires of a different size, the speedometer must be updated with new tire size information. Otherwise, the vehicle's computer will be unable to correctly calculate the vehicle's speed.

Speed Sensor Malfunction

The vehicle speed sensor monitors the speed at which the vehicle's wheels are spinning and uses that data to calculate the vehicle's speed. Malfunction of the speed sensor can cause the speedometer to display incorrect information, to jump around or to fail to move. Malfunction of the VSS can also cause failure or unreliability of other systems, such as anti-lock braking, automatic transmission, cruise control and power steering.

Programmable Speedometer and Odometer Module

The programmable speedometer and odometer module is a computerized instrument cluster that stores the vehicle's odometer reading and displayed speed information. The PSOM calculates its information based on data provided by the speed sensor. Malfunction of the PSOM would cause both the speedometer and odometer to cease displaying information.

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