well I have after market gauges on my 68 barracuda and never tried to hook up these 2 gauges. amp and fuel gauge work fine. but the temp and oil pressure gauge will give a test light a blinking light when I connect the wire to the test light and the key on. if I leave the test light connected a little longer on the temp sender wire the gauge will move. but the oil gauge will not. any idea's? new harness and sending units.