1956 Oil pressure switch location

[gatech1956]

I installed an electronic ingnition and an alternator. Gen light no longer comes on when key moves to on (I expected that). However oil light isn’t coming on anymore. I want to remove the switch and ground the wiring to test the light.

[The Tassie Devil(le)]

How is your Alternator working without the warning light?   Have you installed another one on the dash?   You can use the original Generator light as the Alternator light.

Bruce.

PS.   Sorry I cannot assist you with the oil pressure switch location.

[gatech1956]

Well I should clarify I had a shop installed the alternator or genernator as it looks like a generator but is actually an alternator.

A new light was not installed. The factory one in still there but as a generator light it would only come on when the generator was not charging. All I know is that nothing was messed with the dash connections but the car starts up no problem and I don’t have to worry about the battery not charging while car is in idle or sitting in traffic

[The Tassie Devil(le)]

Okay.   My knowledge in electrics is that when the Alternator is not turning/charging, there is 12 volts going from the ignition to the Alternator via the light, and uses the Alternator as a ground, which in itself supplies the necessary current to excite the Alternator to start charging.

When the Alternator starts turning, and charging, it reverse flows 12 volts back through the light, thereby extinguishing said light, as there is no ground.

If there is no light visible, then there must be some other way to excite the Alternator to work.

The good thing about this light being visible is when, say the Alternator belt breaks, the light illuminates and lets the driver know that something is wrong.

Bruce.

[Roger Zimmermann]

The oil pressure switch is located at the rear of the engine, almost below the intake manifold. It's on the driver's side of the engine block. You probably have to remove the air cleaner to see it and it's not easy to remove unless you have a specific wrench. To test the switch/bulb, just disconnect the wire and connect it to the ground. The oil pressure lamp should come on.
I find strange that with the key "on" and the engine not running you don't have a "gen" light. I would not accept this situation.

[gatech1956]

Roger & Bruce,

Thanks for your responses. I think both of you make good points. I checked the shop manual (these features were working properly when I had the generator/points ignition) and I am going to assume for the moment that the circuits for both lights have been left open, which is one of the possibilities listed by the shop manual. This could have happened when it the car was converted. I will keep checking the wiring in the engine bay.

Thanks

[Lexi]

Yes, I as well would want an operational gen light. Go to Amazon and purchase a $10 plug in LED voltage indicator (plugs into cigarette lighter). That way you can watch battery voltage even while driving. Don't know what the output is for your alternator, but I would imagine the voltage reading when driving would be around 14.5 volts. Might dip into the mid 13 volt range. Clay/Lexi

[gatech1956]

Yes, I as well would want an operational gen light. Go to Amazon and purchase a $10 plug in LED voltage indicator (plugs into cigarette lighter). That way you can watch battery voltage even while driving. Don't know what the output is for your alternator, but I would imagine the voltage reading when driving would be around 14.5 volts. Might dip into the mid 13 volt range. Clay/Lexi

Hi, Lexi. Its a 12 volt alternator, rated at 65 amps at idle and 75 while moving. Looking at the wiring diagram I am going to have to start at the ignition and follow a pink wire. I'm not the most technical person but that is where it looks like the initial power comes from. I need to figure out what changes were made when it was changed from points to electronic.

[Caddy Wizard]

The oil pressure switch is located at the rear of the engine, almost below the intake manifold. It's on the driver's side of the engine block. You probably have to remove the air cleaner to see it and it's not easy to remove unless you have a specific wrench. To test the switch/bulb, just disconnect the wire and connect it to the ground. The oil pressure lamp should come on.
I find strange that with the key "on" and the engine not running you don't have a "gen" light. I would not accept this situation.

Actually, I think the oil pressure light switch (sender) is on the passenger side of the engine, between the distributor and the passenger side cylinder head.  It unscrews with a 1/2 or 9/16 wrench.  Sometimes a "crow's foot" wrench is needed.  Do not use teflon tape or thread sealant on the tapered pipe threads -- that can interfere with the grounding through the switch. The tapered pipe threads (NPT) will seal fine without sealant.

[savemy67]

Hello gatech1956,

I am curious.  If you had a shop install the converted (to alternator) generator, why did they not wire the instruments correctly?  Or would they have charged (no pun intended) extra?

Respectfully submitted,

Christopher Winter

[gatech1956]

Hello gatech1956,

I am curious.  If you had a shop install the converted (to alternator) generator, why did they not wire the instruments correctly?  Or would they have charged (no pun intended) extra?

Respectfully submitted,

Christopher Winter

Good question. The car went through an entire engine bay detail and refinishing. It took a long time and months of waiting, I had been enjoying the car this entire time I just noticed this small detail.

If it ends up going back for to the shop so be it, but I would like to use this as learning opportunity for myself if I can fix it.

[Caddy Wizard]

Regarding the gen light, there are a couple of possibilities.  If they installed a PowerGen alternator (my preferred item),  that unit comes in two versions.  One version has a post for connecting a wire for the generator light.  If you use that one and run the gen light wire to that post, the gen light will operate exactly as it came from the factory -- it will come on when you turn on the key and will go off once the engine is running and the alternator is charging.  The other version they sell doesn't have the gen light post, so if they installed that one, the light will never light up.  The price difference between the two versions is very slight.

[Jeff Rosansky CLC #28373]

How long has the oil light been out? Just thinking out loud here but if the shop installed the wrong alternator and couldn't get the light to go out, maybe they just disconnected the light. Depending on how they did it you could have lost the oil light as well in their atempt to "fix" it. That is how you do it, right?? If a warning light is on the easiest way to fix it is to remove it??

Jeff

[gatech1956]

Regarding the gen light, there are a couple of possibilities.  If they installed a PowerGen alternator (my preferred item),  that unit comes in two versions.  One version has a post for connecting a wire for the generator light.  If you use that one and run the gen light wire to that post, the gen light will operate exactly as it came from the factory -- it will come on when you turn on the key and will go off once the engine is running and the alternator is charging.  The other version they sell doesn't have the gen light post, so if they installed that one, the light will never light up.  The price difference between the two versions is very slight.

Hi, Art.

It was in fact the powergen with generator light post.

[gatech1956]

How long has the oil light been out? Just thinking out loud here but if the shop installed the wrong alternator and couldn't get the light to go out, maybe they just disconnected the light. Depending on how they did it you could have lost the oil light as well in their atempt to "fix" it. That is how you do it, right?? If a warning light is on the easiest way to fix it is to remove it??

Jeff

I do not know the exact details of how they did it. I want to say its been like this since I got it a few months back and just paid attention to it now. I don't think its the "wrong" alternator, I got it from speedway and it was for early GM models such as 1956 cadillac. As far as disconnecting in the light, I have peaked up under the dash many times nothing is disconnected. The dark blue and pink wires are connected to their terminals.

[Caddy Wizard]

Hi, Art.

It was in fact the powergen with generator light post.

Then all that needs to be done is to run a wire to the post.  The original idiot light wire comes from the dash and goes to the voltage regulator.  You would disconnect it there at the voltage regulator and add a little extension to connect it to the post.  Try to use the same color wire.  This is exactly what I had to do with my 55 when adding the PowerGen alternator. Wiring diagram in the Factory Shop Manual will identify the correct wire at the voltage regulator.

[gatech1956]

Oil light started working today all by itself. Next thing is to try what Art said. Wiring diagram says it should be a brown wire.

[Lexi]

I believe Art is correct. Is more on passenger side at rear, about 4 inches from distributor. I recall using a  9/16 " inch wrench. Clay/Lexi

[gatech1956]

So this is strange. The oil light only seems to come on with the ignition on after the engine has been warmed up after driving a little. Is that normal?

[The Tassie Devil(le)]

In a word. NO.   Any oil light coming on when the engine has been running is an indication of very low oil pressure, and should be investigated.

I would be installing an oil pressure gauge, even a temporary one, just to see what the pressure readings are at various temperatures, and revolutions.

Low oil pressure translates to a soon-to-be-dying engine.

Bruce.