Low oil light illuminated with full oil - Page 2 - ZR-1 Net Registry Forums

GOLDCYLON · 05-09-2012

Quote:

Originally Posted by VetteMed

I suppose it's possible that the low oil pressure switch might trigger the "low oil" light? Come to think of it, there is no low oil pressure warning lamp, so what would that switch trigger otherwise??

With no passenger side block sensor like ALL the MY 91s and some of the MY90s it has to have received its signal from one of the three sendors on the oil filter housing. Its not the oil pressure switch on the top next to the oil filter as that feeds the pressure gauge in the IP (the op indicated that is not a problem). The lower two sending units are the likely culprit. GC

VetteMed · 05-09-2012

Well, it would have to be the switch on the side, not the one in the front near the belt tensioner, since that's a temperature sender.

GOLDCYLON · 05-09-2012

Quote:

Originally Posted by VetteMed

Well, it would have to be the switch on the side, not the one in the front near the belt tensioner, since that's a temperature sender.

Concur. There is no other way the ECM would be able to see the data.

BlackbirdZ07 · 05-09-2012

Quote:

Originally Posted by VetteMed

Well, it would have to be the switch on the side, not the one in the front near the belt tensioner, since that's a temperature sender.

That's what I originally thought that switch was for, but I think VetteMed was right at first because I don't see how it could detect the oil level since it's located on the oil filter housing. Anyway, I replaced it as a preventative measure with a new GM part because I read about the failure of this switch that can cause a sudden and large oil leak, and because it was completely accessible with the other work that I was doing when normally it's very hard to get to.

The bulb was missing along with the Service Ride Control light and the airbag light, so I just assumed someone removed the Low Oil light too. However, since there's no sensor or wiring for a sensor, I suspect the bulb never was installed at the factory, and that the car didn't have a Low Oil idiot light.

And yes, it definitely has oil pressure.

BlackbirdZ07 · 05-09-2012

Quote:

Originally Posted by GOLDCYLON

Concur. There is no other way the ECM would be able to see the data.

I'm not sure the light is on because the ECM is seeing data. It may be on because it's not seeing data. In other words, it's not getting feedback from the sensor that the oil level is okay (because there is no sensor), so it turns on the light.

BlackbirdZ07 · 05-09-2012

Quote:

Originally Posted by VetteMed

I suppose it's possible that the low oil pressure switch might trigger the "low oil" light? Come to think of it, there is no low oil pressure warning lamp, so what would that switch trigger otherwise??

Maybe the Check Gauges light??

VetteMed · 05-09-2012

Quote:

Originally Posted by BlackbirdZ07

Maybe the Check Gauges light??

Yeah, that's a possibility. I need to pore over the wiring diagrams to see if the switch provides a feed to the ECM or it's just grounding a light circuit, and which light it is.

VetteMed · 05-09-2012

SO, in a 1991, the CCM controls the low oil light, based on input from the low oil level switch. It's normally grounded (with normal oil level); a break in this ground will trigger the CCM to illuminate the low oil level indicator lamp.

VetteMed · 05-09-2012

Blackbird, it looks like you are correct. The low oil pressure switch, which is closed to ground with low pressure, enables the CCM to illuminate the Check Gauges light. I do not see any other input for the CCM that would illuminate that light. Wonder why they didn't make it a "check oil pressure" light.

BlackbirdZ07 · 05-10-2012

Quote:

Originally Posted by VetteMed

Blackbird, it looks like you are correct. The low oil pressure switch, which is closed to ground with low pressure, enables the CCM to illuminate the Check Gauges light. I do not see any other input for the CCM that would illuminate that light. Wonder why they didn't make it a "check oil pressure" light.

Interesting... Thanks for researching that. I'm going out to the garage right now to pull that bulb!

05-09-2012	#12
VetteMed Join Date: Mar 2009 Location: Orlando, FL Posts: 1,828	Re: Low oil light illuminated with full oil Well, it would have to be the switch on the side, not the one in the front near the belt tensioner, since that's a temperature sender. __________________ 2004 Z06/Z16 LeMans Commemorative Edition 1991 ZR-1 #302 White/Gray (sold) 1991 ZR-1 #1147 Red/Saddle (sold)

05-09-2012	#18
VetteMed Join Date: Mar 2009 Location: Orlando, FL Posts: 1,828	Re: Low oil light illuminated with full oil SO, in a 1991, the CCM controls the low oil light, based on input from the low oil level switch. It's normally grounded (with normal oil level); a break in this ground will trigger the CCM to illuminate the low oil level indicator lamp. __________________ 2004 Z06/Z16 LeMans Commemorative Edition 1991 ZR-1 #302 White/Gray (sold) 1991 ZR-1 #1147 Red/Saddle (sold) Last edited by VetteMed; 05-09-2012 at 09:03 PM.

05-09-2012	#19
VetteMed Join Date: Mar 2009 Location: Orlando, FL Posts: 1,828	Re: Low oil light illuminated with full oil Blackbird, it looks like you are correct. The low oil pressure switch, which is closed to ground with low pressure, enables the CCM to illuminate the Check Gauges light. I do not see any other input for the CCM that would illuminate that light. Wonder why they didn't make it a "check oil pressure" light. __________________ 2004 Z06/Z16 LeMans Commemorative Edition 1991 ZR-1 #302 White/Gray (sold) 1991 ZR-1 #1147 Red/Saddle (sold)