M1078A0 oil light on only when in gear.

[Ned81]

Went for a drive tonight and my oil light came on but it was dim. I pulled over and checked everything. Good pressure, no leaks. I noticed that the light was only on when I was in gear and went off in neutral. Any ideas?


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[coachgeo]

Went for a drive tonight and my oil light came on but it was dim. I pulled over and checked everything. Good pressure, no leaks. I noticed that the light was only on when I was in gear and went off in neutral. Any ideas?


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curios...... Wonder if dash oil light comes on if trans is low on oil? It's already been established the way you check for low oil on on wtechII keypads such as ones in Motor-homes is not programmed into our keypads....

 

[Ned81]

curios...... Wonder if dash oil light comes on if trans is low on oil?

I was thinking about that too. It’s cold and dark now but my curiosity might force me to go check it.


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[Ned81]

I checked the trans oil and it’s right on. I rechecked the engine oil on level ground this time, it at the bottom of the add mark. I’ll top it off tomorrow but the light only being in in gear is odd.


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[Ronmar]

No idiot light monitoring of the trans on the A0.

I would suspect that your oil pressure switch is full of crap/corrosion and starting to short out… the neutral start contacts from the trans interact with that oil pressure light, start lockout and alt excite circuitry.

if you remove the diode pack that contains diode D3B in the power panel This will separate the neutral start half of the circuit. The light should still remain even when you shift into neutral. If it does the oil switch is most likley passing enough current to dimly light the oil lamp…

you could also disconnect the oil pressure switch after startup to confirm it as the source of the current Lighting the lamp…

 

[Ned81]

No idiot light monitoring of the trans on the A0.

I would suspect that your oil pressure switch is full of crap/corrosion and starting to short out… the neutral start contacts from the trans interact with that oil pressure light, start lockout and alt excite circuitry.

if you remove the diode pack that contains diode D3B in the power panel This will separate the neutral start half of the circuit. The light should still remain even when you shift into neutral. If it does the oil switch is most likley passing enough current to dimly light the oil lamp…

you could also disconnect the oil pressure switch after startup to confirm it as the source of the current Lighting the lamp…

I’m betting oil pressure switch. The gauge doesn’t seem to act correctly. The pressure is all over the place. Always good but sometimes 40 and sometimes 80psi. I was thinking a ground or short somewhere because of the dim light.
Are you talking about the switch on the engine?


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[Ronmar]

I’m betting oil pressure switch. The gauge doesn’t seem to act correctly. The pressure is all over the place. Always good but sometimes 40 and sometimes 80psi. I was thinking a ground or short somewhere because of the dim light.
Are you talking about the switch on the engine?


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Yes the switch down on the drivers side of the engine. The oil switch and the oil pressure sender that drives the gauge are 2 separate components. The switch is the smaller one toward the rear, the gauge sender is forward and larger…

 

[Ned81]

Yes the switch down on the drivers side of the engine. The oil switch and the oil pressure sender that drives the gauge are 2 separate components. The switch is the smaller one toward the rear, the gauge sender is forward and larger…

So this is what I need. I can’t find one anywhere. Do you think a cat 3116 switch would work?

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[coachgeo]

Oil Pressure Switch 15psi ,Normal Closed, Floating Ground

Napa

701-1578

above is the alternative listed to work for LMTV in yellow parts spread sheet sticky/pinned to top of this page ... it is a few lb pressure difference... though not sure the extra 3psi is enough to be an issue?

 

[Ronmar]

About any 2 terminal oil pressure switch will work, as they are normally closed. Since it provides a path to ground, a single terminal switch would also work you would just need to determine the proper wire of the 2 existing wires to connect to it…

 

[Ned81]

Thanks for the help! I’ll update when I get it fixed.


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