Oil Light Problem

Charging, starting, lighting, gauges, HVAC

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67F100-390
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Oil Light Problem

Post by 67F100-390 »

For some reason my idiot light for the oil pressure is backwards. When the key is on(engine not running) the light is off, and if the engine is running the light comes on. Anybody know what causes this?
67 F-100 Custom Cab Short Bed
428ci 4 speed
Finally runs and drives after 14 long years in a field
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basketcase0302
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Re: Oil Light Problem

Post by basketcase0302 »

Make sure the sending unit is grounded well, (not too much sealer or teflon tape on the sending unit). Could also be the sending unit itself. Unhook the wire from the sending unit to verify if the light goes out.
The truck originally came with an "idiot light" didn't it-not a gauge in the panel?
Jeff
http://www.fordification.com/forum/view ... 22&t=46251
SOLD-71 F-350 dually flatbed, 302 / .030 over V-8 with a "baby"C-6, B & M truckshifter, Dana70/4.11 ratio, intermittent wipers, tilt steering, full LED lighting on the flat bed, and no stereo yet (this way I can hear the rattles to diagnose)! SOLD!
Many Ford bumps / one 76' EB / and several dents through the years.
A lot of "oddball" Ford parts collected from working on them for 34 years now!
2008 Ford Escape 4 x 4
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67F100-390
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Re: Oil Light Problem

Post by 67F100-390 »

It has always had the idoit light. For some reason it quit today and is working normaly now. My guess is the sending unit.
67 F-100 Custom Cab Short Bed
428ci 4 speed
Finally runs and drives after 14 long years in a field
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70_F100
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Re: Oil Light Problem

Post by 70_F100 »

With idiot lights, the sending unit breaks the ground circuit when a specified pressure (IIRC, it's about 6 PSI) is reached, thereby turning the light out.

On the other hand, the sending unit for gauges has a variable ground that is calibrated to pressure. When the pressure increases, the resistance to ground is varied, causing the gauge to change in direct relation.

If you had just changed the sending unit, my guess would be that you got the wrong one. But, since it sounds like nothing has been changed, you could, very well, have a bad sending unit, or possibly just a loose connection somewhere.
Wise men talk because they have something to say; fools talk because they have to say something.--Plato
Why is it that there's seldom time to fix it right the first time, but there's always time to fix it right the second time???

That's not an oil leak :nono: That's SWEAT from all that HORSEPOWER!! :thup:
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