MG Car Repair: Gauges, fuel gauge, minor collision

Question
All of the gauges on my 1980 MGB are nonfunctional except the oil pressure and speedo, which are little better.  The guy I bought the car from says it all happened when he had a minor collision, but I'm not sure I believe him.  What's my starting point to diagnose this?

Thanks!

Answer
Hi Billy,
Pick one gauge like the fuel gauge. You need to check to see if the the gauge you are going to test first has power with a volt meter. It should have about 10v key on. If not check the fusses and if all have power on both sides (Key on) then check the voltage stabilizer to see it is receiving 12v and putting out 10v then check to see that the gauge is grounded. If all of that is correct turn the key on and unplug the green wire on the sending unit at the tank and see if the gauge goes full deflection in either direction and then ground that wire and watch the gauge, it should go full deflection the other way.
Let me know,
Howard