95 C280 warning lights and speedo error

I have a 95 C280 that has been perfect up to this point. This morning I was cruising along and the speedometer died. Also all three brake warning lights came on. Has anyone had this happen before and what could be the cause.We just had our first taste of cold weather and I'm thinking this could be the cause.

a family members had sensor go out in the diff, hers is a 96 c280 with about 70k at the time it went out. replaced by a local mechanic.

her check engine (or is it a service engine light?- I will have to go and look thurs.) has come back on, but the car drives great.
Best of luck.

The fix for this problem was the OVP relay.Quick fix. The relay costs about 70 dollars.Just remove the old one and plug in the new one.