Oil pressure sensor 1983 280zx NT

[alanburton]

Trying to figure out completely erratic readings on my oil pressure gauge. I ordered a NOS sender and it’s still crazy. So I’m wanting to narrow this down. There are two prongs on my sender and somewhere I read that one prong was for the meter and the other prong was for the oil warning light, is that true. If so the changes in pressure would result in changes in resistance to ground for reference. What I wanted to know was is the Oil pressure reading resistance across the two prongs for both the light and meter or is it reading reference of resistance to ground on each with one going for the meter and the other going for the light. Any insight here appreciated.

 

 

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[Zed Head]

18 hours ago, alanburton said:

 What I wanted to know was is the Oil pressure reading resistance across the two prongs for both the light and meter or is it reading reference of resistance to ground on each with one going for the meter and the other going for the light. Any insight here appreciated.

You would measure from prong to ground, for each prong.  Edit - that would be with the sender in the block.  Otherwise, measure from prong to sender threads.  Grounding is through the threads.  One will be a switch and the other a variable resistance.

It's weird how bad the 280ZX FSM's are, considering how good the last 280Z FSM's were.  But I did find it illustrated on page EL-90.  I don't think that they wrote a single word about the oil pressure sender.  This diagram is all there is. @alanburton

Edited February 10, 2019 by Zed Head

[alanburton]

Appreciate the feedback. Looks like the variable resistance connector goes to the meter with the changes in resistance to ground results in changes to the oil pressure meter while the other prong goes to the oil light and goes to full ground potential when oil pressure is not present. If that’s correct I at least know how to start testing.


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[alanburton]

Ok I need some input here. I ordered what was to be a NOS oil sender. It came in the correct Nissan box and all. His was to replace the one I had which was very erratic at best. I put the new one in and connected it and when I started the car it read nothing at all, then after a couple of minutes it started reading about three-quarter scale and then drop back to zero. The car is running just fine I heard the valves clicking or any indication that the engine is under stress. I thought maybe it’s dirty contacts on the connector so I pull the connector and clean the contacts and the connector with electrical cleaner and plug it back in. When I did this and got back in the car the meter was reading for scale it was pegged however as soon as I started the engine it went to zero. When I turn the engine off it goes back over almost all the way with the engine turned off. And here’s another One for the voodoo file. When I get inside the car and the meter is on zero and I stick the key in the ignition without even turning it on the meter goes to three for quarter scale, where the ignition off. When I unplug the connector from the sender Meter reads zero as it should, but is soon as I plug it back in when the engine turned off there it is three-quarter scale. It almost sounds like I got another bad sensor what do you think


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[Zed Head]

Might be the gauge itself, not the sender.  There is some voodoo there also.  This is from 1978.  They stopped describing it in later FSM's.  It's not a great description they don't really tell where the voltage regulator part is.  They blend the sensor and dash gauge all in to one.  But, it might be the gauge.

 

[Pilgrim]

Let's go back to the first post. It's normal for the pressure to be high while driving and drop to almost zero at idle. Have you checked a service manual for the gauge test procedure?

What are the specific readings that you are observing? (To some people the normal oil pressure variation in a Datsun L6 would seem erratic.}

NOTE: If your post #4 describes the behavior that has been going on all along, I doubt the problem is the sending unit, I think it's likely a bad wire or bad connection...perhaps a gauge problem.

Edited September 11, 2019 by Pilgrim