1990 chevy 1500 4/4 half ton wipers don't work? I burnt up wiring on my 90 chevy silverado with carb back fire. Replaced wiring with 1989 chevy same model all plugs matched up except oil pressur switch has 2 prongs 90 chevy has 3 prongs, took sending oil unit off 89 and put it on my 90. Only one more difference was gray wire on 90 by computer plug 89 did not have this and 89 had a red and white wire that does't do any thing on the 90 but 89 had it. My problem is when i turn on the wiper motor the oil meter check guages light and water temp light pulsate back and forth when it is on high speed, no low speed no intermitten and the motor makes a noise on anything but high speed, and windshield washer does not come on when you turn pedal on switch. Wiper motor has same plug as 90, 4 wires and middle black. Tryed grounding black wire but no results. What can i do now, all plugs plugged in but wipers don't work. It's my last problem before it is back to normal. HELP IF YOU CAN'T DON'T KNOW HOW TO FIX IT, sounds like a grounding problem or??? SOULUTIONS PLEASE!!!!!!!