Oil Pressure Sending Unit

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lalkie01
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Joined: Sat Nov 16, 2019 2:02 pm

Oil Pressure Sending Unit

Post by lalkie01 »

I have a 65 Corsa. I replaced the oil pressure sending unit about a year ago. I recently pulled the power pack for repairs. Upon installing the power pack I am unable to get the light on the dash to work when I turn the key on. If I ground the wire the light on the dash works. When I hook it up to the sending unit the light does not work. Testing the sending unit with an ohm meter it shows no resistance. As I understand how the sending unit works it is grounded when there is no pressure and the ground is eliminated when there is pressure. Is there another way to test the sending unit? What am I missing. Thanks Larry

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terribleted
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Re: Oil Pressure Sending Unit

Post by terribleted »

Touching the ohm meter to the wire connector on the top of the sending unit and a good ground should show a direct short when the engine is not running (no pressure). When there is no pressure the switch is closed connecting the bulb which has 12V waiting to ground making it light. When the switch gets pressure it opens this circuit and the light then goes out.
Corvair guy since 1982. I have personally restored at least 20 Vairs, many of them restored ground up.
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Located in Snellville, Georgia

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bbodie52
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Re: Oil Pressure Sending Unit

Post by bbodie52 »

Image

The sending unit is simply an on/off switch. With no oil pressure you should see a direct connect from the electrical contact to ground. When oil pressure is present the switch should open, giving you no connection between the electrical connector and ground.

If you do not get a ground connection through the switch with the engine OFF, but th e warning light illuminates when you touch the wire to GROUND, you have proven the circuit from the connector wire to the instrument panel. The switch itself may be stuck or otherwise faulty internally, and in need of another replacement.
The main problem when replacing the Chevy engine oil pressure sensor is repeat failure. This goes back to the root cause of the issue. Sludge and debris finds its way inside of the old oil pressure switch.

On older Chevy engines that don't have the screen repeat failure often comes from lack of engine maintenance. In some cases this is not the fault of the current owner, but the previous one. A lack of engine oil changes can cause sludge deposits to form.
:link: https://www.fixmyoldride.com/Chevy-engi ... ssure.html
Brad Bodie
Lake Chatuge, North Carolina
Image 1966 Corvair Corsa Convertible

lalkie01
Posts: 32
Joined: Sat Nov 16, 2019 2:02 pm

Re: Oil Pressure Sending Unit

Post by lalkie01 »

Thanks for the response. I thought I was on the right track. Sending unit was probably made in china. I guess I will buy another one. Thanks Larry

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