Oil sending unit wire color

[eoseitz]

The previous owner of my corvette replaced the oil gauge with some cheezy sunpro oil pressure gauge. I bought a new sending unit, but don't know which wire to connect to it. He swapped the motor out and there is a couple wires he never reattached. Does anyone know the color of the wire? I found two wires that have plugins that match the oil sending unit. Both have a full time 12v. I would have thought they would be switched on and off by the key. Any ideas?

 

[cleon]

On my 1979 L-48, the oil pressure wire is a pail or light brown.
On the connector end has a rubber cap that seals the connection around
the end of the sending unit. The wire runs about 8" into the wiring
harness, at the fire wall. I am sure this wire is original.

 

[eoseitz]

I pulled the gauge bezel off yesterday and it appears the wires coming off the oil pressure gauge are blue and pink. However, there are several gauges with blue and pink wires. To make it even worse, I don't see a single blue or pink wire under the hood. Do they change color somewhere in the wiring harness?

I did happen to find a brown wire like you were referring to. I checked it with a volt meter and it has constant 12 volts I believe. Does yours also?

 

[cleon]

I checked my Haynes Repair Manual for 1968 through 1982 Corvette.
The Wiring Diagram, shows the Oil Pressure Gage has 12 v. going into it
from the Fuse Cluster. One wire out to the Pressure Switch. That wire is
TAN. So that wire should have 12 v. There is a notation “Engine Oil Pressure
switch Closed with Normal Oil Pressure.” This is not to say that someone could
have run a new wire to the gage. The pressure switch is then grounded to the engine,
by it’s mounting.

 

[eoseitz]

Ok thanks a lot for your help. I would say it's safe to assume the tan wire I found is the correct one. It definitely looks original and has 12v.

 

[eoseitz]

This thread has been dead for a while, but I just got around to working on my car. I posted another thread about my oil sending unit exploding. They gave me the wrong one. Anyway, back to this thread.

The wire I found that looked brown/tan was due to oil on it. When I trace it back to the firewall it appears to be orange. I guess it could be tan though. It is far longer than it needs to be to plug into the pressure switch by the distributor. There are 2 or three black wires that are the correct length. They all have full time 12 v. Should I just ground these and see if the gauge moves?

I'm not sure if the oil sending unit was originally by the distributor. I've read it could have been by the oil filter. Does anyone else have a 74 that can confirm its location. I could be looking in the wrong spot for the wire.

 

[bill81vette]

I've always known the oil pressure switch to be on the intake behind the distributor....
at least on chevy's....

 

[TimAT]

74 sender was behind the distributor. Some later years they had a temp probe down at the filter and the even later years with fuel injection used another pressure switch by the filter to control the fuel pump.

 

[eoseitz]

Well I tried to find the wire color on the wiring diagram. I got confused though and couldn't figure it out. Could anybody possibly pop their hood and see what color of wire is attached to the oil sending unit.

 

[TimAT]

Wiring diagram shows the oil pressure sender wire to be Dark Blue..

 

[eoseitz]

I've been looking at the wiring diagrams and thought that may be the color. Now the complicated part is figuring out which wire is dark blue or just covered in oil. lol. Thanks a ton for your help.

 

[TimAT]

A rag and some alcohol will go a long way toward cleaning. there are many things better suited to cleaning wires, but most of them will attack the insulation. One thing to look for- the connector has a boot covering the terminal that is supposed to snap on the sender to help keep water out. But from that standpoint, the detent connector for the trans has exactly the same boot on it.

 

[eoseitz]

I found one that has a boot and is dark blue. However, I used a test light on it and it doesn't appear to make the gauge move. I'm hoping the gauge isn't bad. I just bought it. Does anybody know of any aftermarket mechanical replacements. Those are very simple to hook up. I actually already have one but it wont fit in the gauge cluster.

 

[TimAT]

Old school S-W gauges:

I don't even know if this type gauge is still available. You do have to remove all of the tin from the back of the cluster to install them. And then rewire all the lights. The pressure and water temp gauges are mechanical.