# dash oil light



## The Machinist (Mar 6, 2008)

Hello! totally new here. Just purchased an 85 720. Love it so far. I'm wondering if like many cars, when I turn the key to the on position if the oil light should come on to verify that the bulb is good? Many cars I've owned are set up this way, they'll stay on until pressure comes up. Mine is off all the time. thoughts?


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## zanegrey (Dec 5, 2005)

look to see if it is connected to the sending unit..

if it is then it is prollty the bulb..


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## The Machinist (Mar 6, 2008)

Thanks! I've been under the hood trying to find the damned sending unit, the Haynes manual is showing me where to look but for the life of me, I can't find it! Where is it in relation to the nearly impossible to reach oil filter?


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## Abeerdrinker (Jan 8, 2008)

back of the block a little towards the top


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## The Machinist (Mar 6, 2008)

Thanks for the reply, left side or right? want to fix this weekend, I just bought the truck and want to make sure there's no problems. Also noticed the knocking sound that last 1/2 a second at startup, gonna change to a Nissan oil filter.


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## 68Datsun510 (Jan 19, 2009)

I am having the same problem on my 87 HB KA=24E, the sending unit under the filter looks like a dummy unit, simply a hole plug, no oil light ever...


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## Peterdaniel (May 24, 2005)

You mean your '97? thats no dummy unit. Thats your sending unit which are notorious for going bad and they leak alot. The plastic that holds the male connector usually dries out and then leaks. Simple fix.

And yes the light should always go on when you start the car. The goes out as oil pressure builds past the cut off value.


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## 68Datsun510 (Jan 19, 2009)

Yep, they got it right 40 years ago but then forgot in 97 with unreliable switches, nice!


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## 68Datsun510 (Jan 19, 2009)

I didnt see a plug, or any wires connected to it, hence why i called it a dummy.


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## Peterdaniel (May 24, 2005)

Hmmmm... I will have to look at that one again.. I know that there is a switch below the filter for sure though.. maybe theres something else Im missing.. my brain perhaps.


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## 68Datsun510 (Jan 19, 2009)

Well, found the problem, some lube monkey bashing around with his oil filter wrench ripped the wire and smashed the plug INSIDE that rubber boot, the boot hid the smashed bits.

Found the wire hiding behind the alternator...funny, 40 years later,the oil sensor wire is the same color! yellow/black stripe


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## dvdswanson (Nov 6, 2005)

the switch is right about the oil filter, looks like this...










if its connected or disconnected and the oil light is not on, its the bulb.


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## Peterdaniel (May 24, 2005)

i believe that is a ground switch with a set of 'points" inside of it something like that.. when the oil pressure falls below a certain pre-determined set point psi, the points ground ( close) and the switch is grounded turning on the light.

if the wire is NOT connected, it would not be grounded and the light would NOT come on.


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## dvdswanson (Nov 6, 2005)

ECM would turn it on then


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## Peterdaniel (May 24, 2005)

where do you get this info from?


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## 68Datsun510 (Jan 19, 2009)

Its a simple switched ground, if its unhooked, no circuit, therefore, no light, theres no ECM involvement.


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## dvdswanson (Nov 6, 2005)

thats why its an idiot light, ooops, I'm not perfect sometimes I give incorrect info.


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## 68Datsun510 (Jan 19, 2009)

[email protected]

happens to everyone

now trying to get crimping pliers up in that gap, yikes...


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