Help! Oil Sending Unit Exploded!!!

[eoseitz]

I replaced my oil gauge today and my oil sending unit. Someone had switched it out for an after market gauge and I want to put it back to stock. I have the gauge hooked up and tightend down the oil sending unit. I was told I was supposed to hook an orange wire to it. The wire is extremely long though. There is a black wire that would fit perfectly. When I hooked up the orange wire and started the car, the oil sending unit blew apart. Did I hook up the wrong wire or was it a defective oil sending unit?

Thanks for your help

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[TimAT]

If I remember, the orange wire is the detent power for the trans (TH400). That gave the sender 12v when you turned the key on. I'll be it was not happy.

Use a 12v testlight, ground the clip, probe the black wire with the key on. If the light glows and the gauge indicates 1/2 scale, that's the OP sender wire.

 

[eoseitz]

Well after looking online and contacting autozone, I found that they gave me the wrong oil sending unit. I was supposed to have a ps133 and they gave me a much smaller ps24. lol. They "couldn't find it in their computer" so the lifetime warranty didn't mean too much. I was stuck buying a new one. I'll check the black wire, but I believe it is hot full time. I want to double check though. I have an aftermarket edelbrock performer intake. It appears in order to to install this new sending unit, I'll have to remove the distributor to make room. Does this sound right?

Hooking the orange wire to the sending unit wouldn't have harmed my gauge would it? I saw the gauge slightly move right before the sending unit went cabooom. I'm assuming as long as it wasn't over 12 volts the gauge should be ok?

 

[TimAT]

There should be enough room to replace the sender without touching the distributor- think about that for a minute- would GM have paid dealer mechanics to pull the distributor to replace that sender under warranty? No way. They even had a special socket that fit the sender.

With both the orange and black wires disconnected, turn the key on. The gauge should go full scale. (right) Add some resistance (a light bulb) and the gauge will swing back to the left. Ground the wire, and the gauge will go full scale to the stop on the left. I use a testlight for a quick and dirty test- an 1894 bulb in a testlight the gauge will read about 1/2 scale- works on gas gauges, temp gauges, and oil pressure gauges. Learned that one back in my dealer wrench days. All the gauges are on the same fuse, so if it popped, all the gauges are dead.


This link to AZ :http://www.autozone.com/autozone/parts/1971-Chevrolet-Corvette/Oil-Pressure-Switch/_/N-iq0ntZ9ciau
it says that it's for a light-

 

[eoseitz]

Well I cross referenced the oil sending unit with the one from AC delco that advanced auto is selling. They look identical to the one I have now. I think I'm good as far as the sending unit now. I really just need to know what wire connects to the sending unit though. Can I test the wires under the hood safely with a test light or just the gauge?

 

[TimAT]

Testlight will work just fine. Key on, probe the connector- the oil pressure wire will just make the light glow, it won't be full bright unless the gauge is shorted internally. With the testlight in place of the sender, the gauge will be about 1/2 scale.
Have you got the wiring diagram for your car?

Index of /johdotukset

Almost forgot- the senders look the same for a light or a gauge.

 

[eoseitz]

Thanks for your help. I actually didn't have the wiring diagram for my car. This will help me with several upcoming repairs.