"Service" and "Service Engine Soon" lights are on. No DTC codes are showing. Engine runs great, transmission shifts perfectly. No known issues or problems. If the lights weren't on you'd swear the Vue was perfect. The only other indicator is the Tach. At cruise speed it will drop to "0" then pop back up to right RPM. It wil do this every minute or so, no regular pattern like there's a short, but I don't believe a short is the issue.

My Question: Why are the lights on and the Tach acting strange? BCM? or what? Thanks.
Putnam