My friend has a 97 civic lx and he ran in to the back of an SUV the other day, but the car is still driveable but anyways the check engine light came on and his speedometer goes back and forth from 0 to 120 when driving and even when he stops at red light but if he taps the brakes it hits 120 and stops the while his foot is on the brake. Well if anybody nows whats wrong with the car could you please tell.

 

check your grounds and run the code and see what the problem is...

 

we have checked all the grounds but haven't checked the codes yet

 

Do that and post what you find.