gauge problems
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Joined: Jan 2001
Posts: 56,950
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From: Virginia
For the oil pressure gauge and the water temp gauge, find the sending units on the engine. One will have a red/white wire and the other will have a white/red wire. The oil pressure sending unit is usually down low near the oil filter on a 351w.
With the key in run, engine off, take the wire off the sending unit and ground it to the block. The gauge should swing full scale hot or cold, low or high pressure, depending on which sending unit wire you are grounding. Then take the wire off the block and let it hang in the air, and the gauge should swing the opposite direction. If this works, then the wiring and the gauge are good, and you have a bad sending unit.
With the key in run, engine off, take the wire off the sending unit and ground it to the block. The gauge should swing full scale hot or cold, low or high pressure, depending on which sending unit wire you are grounding. Then take the wire off the block and let it hang in the air, and the gauge should swing the opposite direction. If this works, then the wiring and the gauge are good, and you have a bad sending unit.
