Defective speed sensors on the transmission can cause problems with the cruise control and speedometer operation, as well as erratic shifting. The connectors on the sensors can corrode and/or the connector terminals can spread (poor connection), which will create similar symptoms. Any of these problems can cause Check Engine Light illumination.
The Cruise Control and Speedometer May Fail Due to Speed Sensor Issues on Plymouth Grand Voyager
Average mileage: 200,000 (200,000–200,000)
4 people reported this problem
A few days ago, the cruise control was working fine. A couple days ago, I would turn the Cruise on, the light came on fine, but I was having intermittent trouble setting the speed. When I was successful at setting the speed, a short time down the road, the cruise control would stop working (but the light for it stayed on). Sometimes, pressing resume got it going again, sometimes not. Check Engine light is on all of the time (not sure if this is related). The horn works fine and the airbag light goes off after starting the vehicle as it is supposed to.