Oil light , where to start

[Tyson Josh]

Recently I have been doing some fixing on my 87 Comanche. Inline 6. 4x4. Long bed. Automatic. 

I replaced passing gear cable , installed electric fans and removed manual fan. New plugs, wires , rotor, and distributor cap. New oil and filter. ( Not a fram)  My oil light has come on .  I went through my book it's a Haynes and there's nothing in there defining like where my sending unit or signal comes from I'm not very sure on how to check my oil pressure because it's just a dummy light on the dash so I know how to work on cars and I'm somewhat savvy with it but I'm not very electrical familiar any help would be appreciated where to start what to look at. 

 

[jdog]

Verify the senders hooked up, it is next to the oil filter or right below it

[89 MJ]

The passenger side of the block near the oil filter is where the sender is. Pull that sender and verify with a mechanical gauge to know what your pressure actually is. 
 

How long did you run it for? The oil filter needs to fill up to build oil pressure, but that should only take a few seconds. 
 

What kind of oil did you use? These trucks called for 10W30 when new, make sure you used something at least that thick. 

[Tyson Josh]

I did look for the sender. There is not one by the oil filter. There is a brass fitting there and a port that is plugged off where one , I believe, should be . But there is nothing there.

[Tyson Josh]

I use 10w30 high mileage full synthetic Castrol. I let the truck run 3 or 4 min.

[89 MJ]

Ok. Sounds like your oil light is caused by not having the sender in it. That’s a pretty easy fix. 

[llhat]

do you see the connector?  Is it unplugged?

 

I cannot recall if the sender grounds out when zero pressure, illuminating the light... but that may be the case.